[PATCH v3 0/8] DMA: Freescale: driver cleanups and enhancements

[PATCH v3 0/8] DMA: Freescale: driver cleanups and enhancements

[hongbo.zhang]

From: Hongbo Zhang <hongbo.zhang@linaro.org>

Hi Vinod Koul,
Please have a look at the v3 patch set.

v2 -> v3 change:
Only add "chan->pm_state = RUNNING" for patch[8/8].

v1 -> v2 change:
The only one change is introducing a new patch[1/7] to remove the unnecessary
macro FSL_DMA_LD_DEBUG, thus the total patches number is 8 now (was 7)

Hongbo Zhang (8):
  DMA: Freescale: remove the unnecessary FSL_DMA_LD_DEBUG
  DMA: Freescale: unify register access methods
  DMA: Freescale: remove attribute DMA_INTERRUPT of dmaengine
  DMA: Freescale: add fsl_dma_free_descriptor() to reduce code
    duplication
  DMA: Freescale: move functions to avoid forward declarations
  DMA: Freescale: change descriptor release process for supporting
    async_tx
  DMA: Freescale: use spin_lock_bh instead of spin_lock_irqsave
  DMA: Freescale: add suspend resume functions for DMA driver

 drivers/dma/fsldma.c |  591 ++++++++++++++++++++++++++++++++------------------
 drivers/dma/fsldma.h |   33 ++-
 2 files changed, 409 insertions(+), 215 deletions(-)

-- 
1.7.9.5

[PATCH v3 1/8] DMA: Freescale: remove the unnecessary FSL_DMA_LD_DEBUG

[hongbo.zhang]

From: Hongbo Zhang <hongbo.zhang@freescale.com>

Some codes are calling chan_dbg with FSL_DMA_LD_DEBUG surrounded, it is really
unnecessary to use such a macro because chan_dbg is a wrapper of dev_dbg, we do
have corresponding DEBUG macro to switch on/off dev_dbg, and most of the other
codes are also calling chan_dbg directly without using FSL_DMA_LD_DEBUG.

Signed-off-by: Hongbo Zhang <hongbo.zhang@freescale.com>
---
 drivers/dma/fsldma.c |   10 ----------
 1 file changed, 10 deletions(-)

diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index f157c6f..ec50420 100644
--- a/drivers/dma/fsldma.c
+++ b/drivers/dma/fsldma.c
@@ -426,9 +426,7 @@ static struct fsl_desc_sw *fsl_dma_alloc_descriptor(struct fsldma_chan *chan)
 	desc->async_tx.tx_submit = fsl_dma_tx_submit;
 	desc->async_tx.phys = pdesc;
 
-#ifdef FSL_DMA_LD_DEBUG
 	chan_dbg(chan, "LD %p allocated\n", desc);
-#endif
 
 	return desc;
 }
@@ -479,9 +477,7 @@ static void fsldma_free_desc_list(struct fsldma_chan *chan,
 
 	list_for_each_entry_safe(desc, _desc, list, node) {
 		list_del(&desc->node);
-#ifdef FSL_DMA_LD_DEBUG
 		chan_dbg(chan, "LD %p free\n", desc);
-#endif
 		dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
 	}
 }
@@ -493,9 +489,7 @@ static void fsldma_free_desc_list_reverse(struct fsldma_chan *chan,
 
 	list_for_each_entry_safe_reverse(desc, _desc, list, node) {
 		list_del(&desc->node);
-#ifdef FSL_DMA_LD_DEBUG
 		chan_dbg(chan, "LD %p free\n", desc);
-#endif
 		dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
 	}
 }
@@ -832,9 +826,7 @@ static void fsldma_cleanup_descriptor(struct fsldma_chan *chan,
 
 	/* Run the link descriptor callback function */
 	if (txd->callback) {
-#ifdef FSL_DMA_LD_DEBUG
 		chan_dbg(chan, "LD %p callback\n", desc);
-#endif
 		txd->callback(txd->callback_param);
 	}
 
@@ -842,9 +834,7 @@ static void fsldma_cleanup_descriptor(struct fsldma_chan *chan,
 	dma_run_dependencies(txd);
 
 	dma_descriptor_unmap(txd);
-#ifdef FSL_DMA_LD_DEBUG
 	chan_dbg(chan, "LD %p free\n", desc);
-#endif
 	dma_pool_free(chan->desc_pool, desc, txd->phys);
 }
 
-- 
1.7.9.5

[PATCH v3 0/8] DMA: Freescale: driver cleanups and enhancements

[Hongbo Zhang]

Sorry, forgot the cover letter, plus it here.


From: Hongbo Zhang <hongbo.zhang@freescale.com>
Date: Thu, 10 Apr 2014 15:16:31 +0800
Subject: [PATCH v3 0/8] DMA: Freescale: driver cleanups and enhancements

Hi Vinod Koul,
Please have a look at the v3 patch set.

v2 -> v3 change:
Only add "chan->pm_state = RUNNING" for patch[8/8].

v1 -> v2 change:
The only one change is introducing a new patch[1/7] to remove the 
unnecessary
macro FSL_DMA_LD_DEBUG, thus the total patches number is 8 now (was 7)

Hongbo Zhang (8):
   DMA: Freescale: remove the unnecessary FSL_DMA_LD_DEBUG
   DMA: Freescale: unify register access methods
   DMA: Freescale: remove attribute DMA_INTERRUPT of dmaengine
   DMA: Freescale: add fsl_dma_free_descriptor() to reduce code
     duplication
   DMA: Freescale: move functions to avoid forward declarations
   DMA: Freescale: change descriptor release process for supporting
     async_tx
   DMA: Freescale: use spin_lock_bh instead of spin_lock_irqsave
   DMA: Freescale: add suspend resume functions for DMA driver

  drivers/dma/fsldma.c |  591 
++++++++++++++++++++++++++++++++------------------
  drivers/dma/fsldma.h |   33 ++-
  2 files changed, 409 insertions(+), 215 deletions(-)

[PATCH v3 2/8] DMA: Freescale: unify register access methods

[hongbo.zhang]

From: Hongbo Zhang <hongbo.zhang@freescale.com>

Methods of accessing DMA contorller registers are inconsistent, some registers
are accessed by DMA_IN/OUT directly, while others are accessed by functions
get/set_* which are wrappers of DMA_IN/OUT, and even for the BCR register, it
is read by get_bcr but written by DMA_OUT.
This patch unifies the inconsistent methods, all registers are accessed by
get/set_* now.

Signed-off-by: Hongbo Zhang <hongbo.zhang@freescale.com>
---
 drivers/dma/fsldma.c |   52 ++++++++++++++++++++++++++++++++------------------
 1 file changed, 33 insertions(+), 19 deletions(-)

diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index ec50420..5f32cb8 100644
--- a/drivers/dma/fsldma.c
+++ b/drivers/dma/fsldma.c
@@ -61,6 +61,16 @@ static u32 get_sr(struct fsldma_chan *chan)
 	return DMA_IN(chan, &chan->regs->sr, 32);
 }
 
+static void set_mr(struct fsldma_chan *chan, u32 val)
+{
+	DMA_OUT(chan, &chan->regs->mr, val, 32);
+}
+
+static u32 get_mr(struct fsldma_chan *chan)
+{
+	return DMA_IN(chan, &chan->regs->mr, 32);
+}
+
 static void set_cdar(struct fsldma_chan *chan, dma_addr_t addr)
 {
 	DMA_OUT(chan, &chan->regs->cdar, addr | FSL_DMA_SNEN, 64);
@@ -71,6 +81,11 @@ static dma_addr_t get_cdar(struct fsldma_chan *chan)
 	return DMA_IN(chan, &chan->regs->cdar, 64) & ~FSL_DMA_SNEN;
 }
 
+static void set_bcr(struct fsldma_chan *chan, u32 val)
+{
+	DMA_OUT(chan, &chan->regs->bcr, val, 32);
+}
+
 static u32 get_bcr(struct fsldma_chan *chan)
 {
 	return DMA_IN(chan, &chan->regs->bcr, 32);
@@ -135,7 +150,7 @@ static void set_ld_eol(struct fsldma_chan *chan, struct fsl_desc_sw *desc)
 static void dma_init(struct fsldma_chan *chan)
 {
 	/* Reset the channel */
-	DMA_OUT(chan, &chan->regs->mr, 0, 32);
+	set_mr(chan, 0);
 
 	switch (chan->feature & FSL_DMA_IP_MASK) {
 	case FSL_DMA_IP_85XX:
@@ -144,16 +159,15 @@ static void dma_init(struct fsldma_chan *chan)
 		 * EOLNIE - End of links interrupt enable
 		 * BWC - Bandwidth sharing among channels
 		 */
-		DMA_OUT(chan, &chan->regs->mr, FSL_DMA_MR_BWC
-				| FSL_DMA_MR_EIE | FSL_DMA_MR_EOLNIE, 32);
+		set_mr(chan, FSL_DMA_MR_BWC | FSL_DMA_MR_EIE
+			| FSL_DMA_MR_EOLNIE);
 		break;
 	case FSL_DMA_IP_83XX:
 		/* Set the channel to below modes:
 		 * EOTIE - End-of-transfer interrupt enable
 		 * PRC_RM - PCI read multiple
 		 */
-		DMA_OUT(chan, &chan->regs->mr, FSL_DMA_MR_EOTIE
-				| FSL_DMA_MR_PRC_RM, 32);
+		set_mr(chan, FSL_DMA_MR_EOTIE | FSL_DMA_MR_PRC_RM);
 		break;
 	}
 }
@@ -175,10 +189,10 @@ static void dma_start(struct fsldma_chan *chan)
 {
 	u32 mode;
 
-	mode = DMA_IN(chan, &chan->regs->mr, 32);
+	mode = get_mr(chan);
 
 	if (chan->feature & FSL_DMA_CHAN_PAUSE_EXT) {
-		DMA_OUT(chan, &chan->regs->bcr, 0, 32);
+		set_bcr(chan, 0);
 		mode |= FSL_DMA_MR_EMP_EN;
 	} else {
 		mode &= ~FSL_DMA_MR_EMP_EN;
@@ -191,7 +205,7 @@ static void dma_start(struct fsldma_chan *chan)
 		mode |= FSL_DMA_MR_CS;
 	}
 
-	DMA_OUT(chan, &chan->regs->mr, mode, 32);
+	set_mr(chan, mode);
 }
 
 static void dma_halt(struct fsldma_chan *chan)
@@ -200,7 +214,7 @@ static void dma_halt(struct fsldma_chan *chan)
 	int i;
 
 	/* read the mode register */
-	mode = DMA_IN(chan, &chan->regs->mr, 32);
+	mode = get_mr(chan);
 
 	/*
 	 * The 85xx controller supports channel abort, which will stop
@@ -209,14 +223,14 @@ static void dma_halt(struct fsldma_chan *chan)
 	 */
 	if ((chan->feature & FSL_DMA_IP_MASK) == FSL_DMA_IP_85XX) {
 		mode |= FSL_DMA_MR_CA;
-		DMA_OUT(chan, &chan->regs->mr, mode, 32);
+		set_mr(chan, mode);
 
 		mode &= ~FSL_DMA_MR_CA;
 	}
 
 	/* stop the DMA controller */
 	mode &= ~(FSL_DMA_MR_CS | FSL_DMA_MR_EMS_EN);
-	DMA_OUT(chan, &chan->regs->mr, mode, 32);
+	set_mr(chan, mode);
 
 	/* wait for the DMA controller to become idle */
 	for (i = 0; i < 100; i++) {
@@ -245,7 +259,7 @@ static void fsl_chan_set_src_loop_size(struct fsldma_chan *chan, int size)
 {
 	u32 mode;
 
-	mode = DMA_IN(chan, &chan->regs->mr, 32);
+	mode = get_mr(chan);
 
 	switch (size) {
 	case 0:
@@ -259,7 +273,7 @@ static void fsl_chan_set_src_loop_size(struct fsldma_chan *chan, int size)
 		break;
 	}
 
-	DMA_OUT(chan, &chan->regs->mr, mode, 32);
+	set_mr(chan, mode);
 }
 
 /**
@@ -277,7 +291,7 @@ static void fsl_chan_set_dst_loop_size(struct fsldma_chan *chan, int size)
 {
 	u32 mode;
 
-	mode = DMA_IN(chan, &chan->regs->mr, 32);
+	mode = get_mr(chan);
 
 	switch (size) {
 	case 0:
@@ -291,7 +305,7 @@ static void fsl_chan_set_dst_loop_size(struct fsldma_chan *chan, int size)
 		break;
 	}
 
-	DMA_OUT(chan, &chan->regs->mr, mode, 32);
+	set_mr(chan, mode);
 }
 
 /**
@@ -312,10 +326,10 @@ static void fsl_chan_set_request_count(struct fsldma_chan *chan, int size)
 
 	BUG_ON(size > 1024);
 
-	mode = DMA_IN(chan, &chan->regs->mr, 32);
+	mode = get_mr(chan);
 	mode |= (__ilog2(size) << 24) & 0x0f000000;
 
-	DMA_OUT(chan, &chan->regs->mr, mode, 32);
+	set_mr(chan, mode);
 }
 
 /**
@@ -889,9 +903,9 @@ static void fsl_chan_xfer_ld_queue(struct fsldma_chan *chan)
 	if ((chan->feature & FSL_DMA_IP_MASK) == FSL_DMA_IP_85XX) {
 		u32 mode;
 
-		mode = DMA_IN(chan, &chan->regs->mr, 32);
+		mode = get_mr(chan);
 		mode &= ~FSL_DMA_MR_CS;
-		DMA_OUT(chan, &chan->regs->mr, mode, 32);
+		set_mr(chan, mode);
 	}
 
 	/*
-- 
1.7.9.5

RE: [PATCH v3 2/8] DMA: Freescale: unify register access methods

[David Laight]

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DQogICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgXl4NCj4gYXJlIGFjY2Vzc2VkIGJ5IERN
QV9JTi9PVVQgZGlyZWN0bHksIHdoaWxlIG90aGVycyBhcmUgYWNjZXNzZWQgYnkgZnVuY3Rpb25z
DQo+IGdldC9zZXRfKiB3aGljaCBhcmUgd3JhcHBlcnMgb2YgRE1BX0lOL09VVCwgYW5kIGV2ZW4g
Zm9yIHRoZSBCQ1IgcmVnaXN0ZXIsIGl0DQo+IGlzIHJlYWQgYnkgZ2V0X2JjciBidXQgd3JpdHRl
biBieSBETUFfT1VULg0KPiBUaGlzIHBhdGNoIHVuaWZpZXMgdGhlIGluY29uc2lzdGVudCBtZXRo
b2RzLCBhbGwgcmVnaXN0ZXJzIGFyZSBhY2Nlc3NlZCBieQ0KPiBnZXQvc2V0Xyogbm93Lg0KDQoJ
RGF2aWQNCg0K

Re: [PATCH v3 2/8] DMA: Freescale: unify register access methods

[Hongbo Zhang]

On 04/10/2014 04:46 PM, David Laight wrote:
> From: hongbo.zhang@freescale.com
>> Methods of accessing DMA contorller registers are inconsistent, some registers
>                                 ^^

Thanks.
sorry, that it a typo.
I would wait to see if there are other defects I have to correct, if yes 
I can send a new iteration including this update, if no I would like to 
know if the maintainer can do me the favor to correct it when merging 
this patch, if still no, I will send a new iteration for this then.

>> are accessed by DMA_IN/OUT directly, while others are accessed by functions
>> get/set_* which are wrappers of DMA_IN/OUT, and even for the BCR register, it
>> is read by get_bcr but written by DMA_OUT.
>> This patch unifies the inconsistent methods, all registers are accessed by
>> get/set_* now.
> 	David
>

[PATCH v3 3/8] DMA: Freescale: remove attribute DMA_INTERRUPT of dmaengine

[hongbo.zhang]

From: Hongbo Zhang <hongbo.zhang@freescale.com>

Delete attribute DMA_INTERRUPT because fsldma doesn't support this function,
exception will be thrown if talitos is used to offload xor at the same time.

Signed-off-by: Hongbo Zhang <hongbo.zhang@freescale.com>
Signed-off-by: Qiang Liu <qiang.liu@freescale.com>
---
 drivers/dma/fsldma.c |   31 -------------------------------
 1 file changed, 31 deletions(-)

diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index 5f32cb8..b71cc04 100644
--- a/drivers/dma/fsldma.c
+++ b/drivers/dma/fsldma.c
@@ -528,35 +528,6 @@ static void fsl_dma_free_chan_resources(struct dma_chan *dchan)
 }
 
 static struct dma_async_tx_descriptor *
-fsl_dma_prep_interrupt(struct dma_chan *dchan, unsigned long flags)
-{
-	struct fsldma_chan *chan;
-	struct fsl_desc_sw *new;
-
-	if (!dchan)
-		return NULL;
-
-	chan = to_fsl_chan(dchan);
-
-	new = fsl_dma_alloc_descriptor(chan);
-	if (!new) {
-		chan_err(chan, "%s\n", msg_ld_oom);
-		return NULL;
-	}
-
-	new->async_tx.cookie = -EBUSY;
-	new->async_tx.flags = flags;
-
-	/* Insert the link descriptor to the LD ring */
-	list_add_tail(&new->node, &new->tx_list);
-
-	/* Set End-of-link to the last link descriptor of new list */
-	set_ld_eol(chan, new);
-
-	return &new->async_tx;
-}
-
-static struct dma_async_tx_descriptor *
 fsl_dma_prep_memcpy(struct dma_chan *dchan,
 	dma_addr_t dma_dst, dma_addr_t dma_src,
 	size_t len, unsigned long flags)
@@ -1308,12 +1279,10 @@ static int fsldma_of_probe(struct platform_device *op)
 	fdev->irq = irq_of_parse_and_map(op->dev.of_node, 0);
 
 	dma_cap_set(DMA_MEMCPY, fdev->common.cap_mask);
-	dma_cap_set(DMA_INTERRUPT, fdev->common.cap_mask);
 	dma_cap_set(DMA_SG, fdev->common.cap_mask);
 	dma_cap_set(DMA_SLAVE, fdev->common.cap_mask);
 	fdev->common.device_alloc_chan_resources = fsl_dma_alloc_chan_resources;
 	fdev->common.device_free_chan_resources = fsl_dma_free_chan_resources;
-	fdev->common.device_prep_dma_interrupt = fsl_dma_prep_interrupt;
 	fdev->common.device_prep_dma_memcpy = fsl_dma_prep_memcpy;
 	fdev->common.device_prep_dma_sg = fsl_dma_prep_sg;
 	fdev->common.device_tx_status = fsl_tx_status;
-- 
1.7.9.5

[PATCH v3 4/8] DMA: Freescale: add fsl_dma_free_descriptor() to reduce code duplication

[hongbo.zhang]

From: Hongbo Zhang <hongbo.zhang@freescale.com>

There are several places where descriptors are freed using identical code.
This patch puts this code into a function to reduce code duplication.

Signed-off-by: Hongbo Zhang <hongbo.zhang@freescale.com>
Signed-off-by: Qiang Liu <qiang.liu@freescale.com>
---
 drivers/dma/fsldma.c |   30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index b71cc04..b5a0ffa 100644
--- a/drivers/dma/fsldma.c
+++ b/drivers/dma/fsldma.c
@@ -418,6 +418,19 @@ static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx)
 }
 
 /**
+ * fsl_dma_free_descriptor - Free descriptor from channel's DMA pool.
+ * @chan : Freescale DMA channel
+ * @desc: descriptor to be freed
+ */
+static void fsl_dma_free_descriptor(struct fsldma_chan *chan,
+		struct fsl_desc_sw *desc)
+{
+	list_del(&desc->node);
+	chan_dbg(chan, "LD %p free\n", desc);
+	dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
+}
+
+/**
  * fsl_dma_alloc_descriptor - Allocate descriptor from channel's DMA pool.
  * @chan : Freescale DMA channel
  *
@@ -489,11 +502,8 @@ static void fsldma_free_desc_list(struct fsldma_chan *chan,
 {
 	struct fsl_desc_sw *desc, *_desc;
 
-	list_for_each_entry_safe(desc, _desc, list, node) {
-		list_del(&desc->node);
-		chan_dbg(chan, "LD %p free\n", desc);
-		dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
-	}
+	list_for_each_entry_safe(desc, _desc, list, node)
+		fsl_dma_free_descriptor(chan, desc);
 }
 
 static void fsldma_free_desc_list_reverse(struct fsldma_chan *chan,
@@ -501,11 +511,8 @@ static void fsldma_free_desc_list_reverse(struct fsldma_chan *chan,
 {
 	struct fsl_desc_sw *desc, *_desc;
 
-	list_for_each_entry_safe_reverse(desc, _desc, list, node) {
-		list_del(&desc->node);
-		chan_dbg(chan, "LD %p free\n", desc);
-		dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
-	}
+	list_for_each_entry_safe_reverse(desc, _desc, list, node)
+		fsl_dma_free_descriptor(chan, desc);
 }
 
 /**
@@ -819,8 +826,7 @@ static void fsldma_cleanup_descriptor(struct fsldma_chan *chan,
 	dma_run_dependencies(txd);
 
 	dma_descriptor_unmap(txd);
-	chan_dbg(chan, "LD %p free\n", desc);
-	dma_pool_free(chan->desc_pool, desc, txd->phys);
+	fsl_dma_free_descriptor(chan, desc);
 }
 
 /**
-- 
1.7.9.5

Re: [PATCH v3 4/8] DMA: Freescale: add fsl_dma_free_descriptor() to reduce code duplication

[Andy Shevchenko]

On Thu, 2014-04-10 at 15:10 +0800, hongbo.zhang@freescale.com wrote:
> From: Hongbo Zhang <hongbo.zhang@freescale.com>
> 
> There are several places where descriptors are freed using identical code.
> This patch puts this code into a function to reduce code duplication.
> 
> Signed-off-by: Hongbo Zhang <hongbo.zhang@freescale.com>
> Signed-off-by: Qiang Liu <qiang.liu@freescale.com>
> ---
>  drivers/dma/fsldma.c |   30 ++++++++++++++++++------------
>  1 file changed, 18 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
> index b71cc04..b5a0ffa 100644
> --- a/drivers/dma/fsldma.c
> +++ b/drivers/dma/fsldma.c
> @@ -418,6 +418,19 @@ static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx)
>  }
>  
>  /**
> + * fsl_dma_free_descriptor - Free descriptor from channel's DMA pool.
> + * @chan : Freescale DMA channel
> + * @desc: descriptor to be freed
> + */
> +static void fsl_dma_free_descriptor(struct fsldma_chan *chan,
> +		struct fsl_desc_sw *desc)
> +{
> +	list_del(&desc->node);
> +	chan_dbg(chan, "LD %p free\n", desc);
> +	dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
> +}
> +
> +/**
>   * fsl_dma_alloc_descriptor - Allocate descriptor from channel's DMA pool.
>   * @chan : Freescale DMA channel
>   *
> @@ -489,11 +502,8 @@ static void fsldma_free_desc_list(struct fsldma_chan *chan,
>  {
>  	struct fsl_desc_sw *desc, *_desc;
>  
> -	list_for_each_entry_safe(desc, _desc, list, node) {
> -		list_del(&desc->node);
> -		chan_dbg(chan, "LD %p free\n", desc);
> -		dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
> -	}
> +	list_for_each_entry_safe(desc, _desc, list, node)
> +		fsl_dma_free_descriptor(chan, desc);
>  }
>  
>  static void fsldma_free_desc_list_reverse(struct fsldma_chan *chan,
> @@ -501,11 +511,8 @@ static void fsldma_free_desc_list_reverse(struct fsldma_chan *chan,
>  {
>  	struct fsl_desc_sw *desc, *_desc;
>  
> -	list_for_each_entry_safe_reverse(desc, _desc, list, node) {
> -		list_del(&desc->node);
> -		chan_dbg(chan, "LD %p free\n", desc);
> -		dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
> -	}
> +	list_for_each_entry_safe_reverse(desc, _desc, list, node)
> +		fsl_dma_free_descriptor(chan, desc);
>  }
>  
>  /**
> @@ -819,8 +826,7 @@ static void fsldma_cleanup_descriptor(struct fsldma_chan *chan,
>  	dma_run_dependencies(txd);
>  
>  	dma_descriptor_unmap(txd);
> -	chan_dbg(chan, "LD %p free\n", desc);
> -	dma_pool_free(chan->desc_pool, desc, txd->phys);
> +	fsl_dma_free_descriptor(chan, desc);

Here is no list_del() call since it's been called in dma_do_tasklet().
What will be the result of double list_del() against the same node?

>  }
>  
>  /**


-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

Re: [PATCH v3 4/8] DMA: Freescale: add fsl_dma_free_descriptor() to reduce code duplication

[Hongbo Zhang]

On 04/10/2014 07:29 PM, Andy Shevchenko wrote:
> On Thu, 2014-04-10 at 15:10 +0800, hongbo.zhang@freescale.com wrote:
>> From: Hongbo Zhang <hongbo.zhang@freescale.com>
>>
>> There are several places where descriptors are freed using identical code.
>> This patch puts this code into a function to reduce code duplication.
>>
>> Signed-off-by: Hongbo Zhang <hongbo.zhang@freescale.com>
>> Signed-off-by: Qiang Liu <qiang.liu@freescale.com>
>> ---
>>   drivers/dma/fsldma.c |   30 ++++++++++++++++++------------
>>   1 file changed, 18 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
>> index b71cc04..b5a0ffa 100644
>> --- a/drivers/dma/fsldma.c
>> +++ b/drivers/dma/fsldma.c
>> @@ -418,6 +418,19 @@ static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx)
>>   }
>>   
>>   /**
>> + * fsl_dma_free_descriptor - Free descriptor from channel's DMA pool.
>> + * @chan : Freescale DMA channel
>> + * @desc: descriptor to be freed
>> + */
>> +static void fsl_dma_free_descriptor(struct fsldma_chan *chan,
>> +		struct fsl_desc_sw *desc)
>> +{
>> +	list_del(&desc->node);
>> +	chan_dbg(chan, "LD %p free\n", desc);
>> +	dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
>> +}
>> +
>> +/**
>>    * fsl_dma_alloc_descriptor - Allocate descriptor from channel's DMA pool.
>>    * @chan : Freescale DMA channel
>>    *
>> @@ -489,11 +502,8 @@ static void fsldma_free_desc_list(struct fsldma_chan *chan,
>>   {
>>   	struct fsl_desc_sw *desc, *_desc;
>>   
>> -	list_for_each_entry_safe(desc, _desc, list, node) {
>> -		list_del(&desc->node);
>> -		chan_dbg(chan, "LD %p free\n", desc);
>> -		dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
>> -	}
>> +	list_for_each_entry_safe(desc, _desc, list, node)
>> +		fsl_dma_free_descriptor(chan, desc);
>>   }
>>   
>>   static void fsldma_free_desc_list_reverse(struct fsldma_chan *chan,
>> @@ -501,11 +511,8 @@ static void fsldma_free_desc_list_reverse(struct fsldma_chan *chan,
>>   {
>>   	struct fsl_desc_sw *desc, *_desc;
>>   
>> -	list_for_each_entry_safe_reverse(desc, _desc, list, node) {
>> -		list_del(&desc->node);
>> -		chan_dbg(chan, "LD %p free\n", desc);
>> -		dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
>> -	}
>> +	list_for_each_entry_safe_reverse(desc, _desc, list, node)
>> +		fsl_dma_free_descriptor(chan, desc);
>>   }
>>   
>>   /**
>> @@ -819,8 +826,7 @@ static void fsldma_cleanup_descriptor(struct fsldma_chan *chan,
>>   	dma_run_dependencies(txd);
>>   
>>   	dma_descriptor_unmap(txd);
>> -	chan_dbg(chan, "LD %p free\n", desc);
>> -	dma_pool_free(chan->desc_pool, desc, txd->phys);
>> +	fsl_dma_free_descriptor(chan, desc);
> Here is no list_del() call since it's been called in dma_do_tasklet().
> What will be the result of double list_del() against the same node?

Not clear with your point.
This patch is only introducing a common fsl_dma_free_descriptor() to 
reduce code duplication. And later in the patch 6/8 the 
fsldma_cleanup_descriptor() is replaced by fsldma_cleanup_descriptorS().

>>   }
>>   
>>   /**
>

Re: [PATCH v3 4/8] DMA: Freescale: add fsl_dma_free_descriptor() to reduce code duplication

[Andy Shevchenko]

On Fri, 2014-04-11 at 16:14 +0800, Hongbo Zhang wrote:
> On 04/10/2014 07:29 PM, Andy Shevchenko wrote:
> > On Thu, 2014-04-10 at 15:10 +0800, hongbo.zhang@freescale.com wrote:

[]

> >> @@ -819,8 +826,7 @@ static void fsldma_cleanup_descriptor(struct fsldma_chan *chan,
> >>   	dma_run_dependencies(txd);
> >>   
> >>   	dma_descriptor_unmap(txd);
> >> -	chan_dbg(chan, "LD %p free\n", desc);
> >> -	dma_pool_free(chan->desc_pool, desc, txd->phys);
> >> +	fsl_dma_free_descriptor(chan, desc);
> > Here is no list_del() call since it's been called in dma_do_tasklet().
> > What will be the result of double list_del() against the same node?
> 
> Not clear with your point.
> This patch is only introducing a common fsl_dma_free_descriptor() to 
> reduce code duplication. And later in the patch 6/8 the 
> fsldma_cleanup_descriptor() is replaced by fsldma_cleanup_descriptorS().

In the last case you could have a broken kernel which will fails on
double list_del(). I think it's better to leave this one untouched and
you may remove it later.

Or move this patch after you have removed that lines.

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

Re: [PATCH v3 4/8] DMA: Freescale: add fsl_dma_free_descriptor() to reduce code duplication

[Hongbo Zhang]

On 04/14/2014 09:40 PM, Andy Shevchenko wrote:
> On Fri, 2014-04-11 at 16:14 +0800, Hongbo Zhang wrote:
>> On 04/10/2014 07:29 PM, Andy Shevchenko wrote:
>>> On Thu, 2014-04-10 at 15:10 +0800, hongbo.zhang@freescale.com wrote:
> []
>
>>>> @@ -819,8 +826,7 @@ static void fsldma_cleanup_descriptor(struct fsldma_chan *chan,
>>>>    	dma_run_dependencies(txd);
>>>>    
>>>>    	dma_descriptor_unmap(txd);
>>>> -	chan_dbg(chan, "LD %p free\n", desc);
>>>> -	dma_pool_free(chan->desc_pool, desc, txd->phys);
>>>> +	fsl_dma_free_descriptor(chan, desc);
>>> Here is no list_del() call since it's been called in dma_do_tasklet().
>>> What will be the result of double list_del() against the same node?
>> Not clear with your point.
>> This patch is only introducing a common fsl_dma_free_descriptor() to
>> reduce code duplication. And later in the patch 6/8 the
>> fsldma_cleanup_descriptor() is replaced by fsldma_cleanup_descriptorS().
> In the last case you could have a broken kernel which will fails on
> double list_del(). I think it's better to leave this one untouched and
> you may remove it later.
>
> Or move this patch after you have removed that lines.
>

Good catch, thank you Andy.
Yes I prefer to leave this untouched and handle it later.

[PATCH v3 5/8] DMA: Freescale: move functions to avoid forward declarations

[hongbo.zhang]

From: Hongbo Zhang <hongbo.zhang@freescale.com>

These functions will be modified in the next patch in the series. By moving the
function in a patch separate from the changes, it will make review easier.

Signed-off-by: Hongbo Zhang <hongbo.zhang@freescale.com>
Signed-off-by: Qiang Liu <qiang.liu@freescale.com>
---
 drivers/dma/fsldma.c |  188 +++++++++++++++++++++++++-------------------------
 1 file changed, 94 insertions(+), 94 deletions(-)

diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index b5a0ffa..968877f 100644
--- a/drivers/dma/fsldma.c
+++ b/drivers/dma/fsldma.c
@@ -459,6 +459,100 @@ static struct fsl_desc_sw *fsl_dma_alloc_descriptor(struct fsldma_chan *chan)
 }
 
 /**
+ * fsl_chan_xfer_ld_queue - transfer any pending transactions
+ * @chan : Freescale DMA channel
+ *
+ * HARDWARE STATE: idle
+ * LOCKING: must hold chan->desc_lock
+ */
+static void fsl_chan_xfer_ld_queue(struct fsldma_chan *chan)
+{
+	struct fsl_desc_sw *desc;
+
+	/*
+	 * If the list of pending descriptors is empty, then we
+	 * don't need to do any work at all
+	 */
+	if (list_empty(&chan->ld_pending)) {
+		chan_dbg(chan, "no pending LDs\n");
+		return;
+	}
+
+	/*
+	 * The DMA controller is not idle, which means that the interrupt
+	 * handler will start any queued transactions when it runs after
+	 * this transaction finishes
+	 */
+	if (!chan->idle) {
+		chan_dbg(chan, "DMA controller still busy\n");
+		return;
+	}
+
+	/*
+	 * If there are some link descriptors which have not been
+	 * transferred, we need to start the controller
+	 */
+
+	/*
+	 * Move all elements from the queue of pending transactions
+	 * onto the list of running transactions
+	 */
+	chan_dbg(chan, "idle, starting controller\n");
+	desc = list_first_entry(&chan->ld_pending, struct fsl_desc_sw, node);
+	list_splice_tail_init(&chan->ld_pending, &chan->ld_running);
+
+	/*
+	 * The 85xx DMA controller doesn't clear the channel start bit
+	 * automatically at the end of a transfer. Therefore we must clear
+	 * it in software before starting the transfer.
+	 */
+	if ((chan->feature & FSL_DMA_IP_MASK) == FSL_DMA_IP_85XX) {
+		u32 mode;
+
+		mode = get_mr(chan);
+		mode &= ~FSL_DMA_MR_CS;
+		set_mr(chan, mode);
+	}
+
+	/*
+	 * Program the descriptor's address into the DMA controller,
+	 * then start the DMA transaction
+	 */
+	set_cdar(chan, desc->async_tx.phys);
+	get_cdar(chan);
+
+	dma_start(chan);
+	chan->idle = false;
+}
+
+/**
+ * fsldma_cleanup_descriptor - cleanup and free a single link descriptor
+ * @chan: Freescale DMA channel
+ * @desc: descriptor to cleanup and free
+ *
+ * This function is used on a descriptor which has been executed by the DMA
+ * controller. It will run any callbacks, submit any dependencies, and then
+ * free the descriptor.
+ */
+static void fsldma_cleanup_descriptor(struct fsldma_chan *chan,
+				      struct fsl_desc_sw *desc)
+{
+	struct dma_async_tx_descriptor *txd = &desc->async_tx;
+
+	/* Run the link descriptor callback function */
+	if (txd->callback) {
+		chan_dbg(chan, "LD %p callback\n", desc);
+		txd->callback(txd->callback_param);
+	}
+
+	/* Run any dependencies */
+	dma_run_dependencies(txd);
+
+	dma_descriptor_unmap(txd);
+	fsl_dma_free_descriptor(chan, desc);
+}
+
+/**
  * fsl_dma_alloc_chan_resources - Allocate resources for DMA channel.
  * @chan : Freescale DMA channel
  *
@@ -803,100 +897,6 @@ static int fsl_dma_device_control(struct dma_chan *dchan,
 }
 
 /**
- * fsldma_cleanup_descriptor - cleanup and free a single link descriptor
- * @chan: Freescale DMA channel
- * @desc: descriptor to cleanup and free
- *
- * This function is used on a descriptor which has been executed by the DMA
- * controller. It will run any callbacks, submit any dependencies, and then
- * free the descriptor.
- */
-static void fsldma_cleanup_descriptor(struct fsldma_chan *chan,
-				      struct fsl_desc_sw *desc)
-{
-	struct dma_async_tx_descriptor *txd = &desc->async_tx;
-
-	/* Run the link descriptor callback function */
-	if (txd->callback) {
-		chan_dbg(chan, "LD %p callback\n", desc);
-		txd->callback(txd->callback_param);
-	}
-
-	/* Run any dependencies */
-	dma_run_dependencies(txd);
-
-	dma_descriptor_unmap(txd);
-	fsl_dma_free_descriptor(chan, desc);
-}
-
-/**
- * fsl_chan_xfer_ld_queue - transfer any pending transactions
- * @chan : Freescale DMA channel
- *
- * HARDWARE STATE: idle
- * LOCKING: must hold chan->desc_lock
- */
-static void fsl_chan_xfer_ld_queue(struct fsldma_chan *chan)
-{
-	struct fsl_desc_sw *desc;
-
-	/*
-	 * If the list of pending descriptors is empty, then we
-	 * don't need to do any work at all
-	 */
-	if (list_empty(&chan->ld_pending)) {
-		chan_dbg(chan, "no pending LDs\n");
-		return;
-	}
-
-	/*
-	 * The DMA controller is not idle, which means that the interrupt
-	 * handler will start any queued transactions when it runs after
-	 * this transaction finishes
-	 */
-	if (!chan->idle) {
-		chan_dbg(chan, "DMA controller still busy\n");
-		return;
-	}
-
-	/*
-	 * If there are some link descriptors which have not been
-	 * transferred, we need to start the controller
-	 */
-
-	/*
-	 * Move all elements from the queue of pending transactions
-	 * onto the list of running transactions
-	 */
-	chan_dbg(chan, "idle, starting controller\n");
-	desc = list_first_entry(&chan->ld_pending, struct fsl_desc_sw, node);
-	list_splice_tail_init(&chan->ld_pending, &chan->ld_running);
-
-	/*
-	 * The 85xx DMA controller doesn't clear the channel start bit
-	 * automatically at the end of a transfer. Therefore we must clear
-	 * it in software before starting the transfer.
-	 */
-	if ((chan->feature & FSL_DMA_IP_MASK) == FSL_DMA_IP_85XX) {
-		u32 mode;
-
-		mode = get_mr(chan);
-		mode &= ~FSL_DMA_MR_CS;
-		set_mr(chan, mode);
-	}
-
-	/*
-	 * Program the descriptor's address into the DMA controller,
-	 * then start the DMA transaction
-	 */
-	set_cdar(chan, desc->async_tx.phys);
-	get_cdar(chan);
-
-	dma_start(chan);
-	chan->idle = false;
-}
-
-/**
  * fsl_dma_memcpy_issue_pending - Issue the DMA start command
  * @chan : Freescale DMA channel
  */
-- 
1.7.9.5

[PATCH v3 6/8] DMA: Freescale: change descriptor release process for supporting async_tx

[hongbo.zhang]

From: Hongbo Zhang <hongbo.zhang@freescale.com>

Fix the potential risk when enable config NET_DMA and ASYNC_TX. Async_tx is
lack of support in current release process of dma descriptor, all descriptors
will be released whatever is acked or no-acked by async_tx, so there is a
potential race condition when dma engine is uesd by others clients (e.g. when
enable NET_DMA to offload TCP).

In our case, a race condition which is raised when use both of talitos and
dmaengine to offload xor is because napi scheduler will sync all pending
requests in dma channels, it affects the process of raid operations due to
ack_tx is not checked in fsl dma. The no-acked descriptor is freed which is
submitted just now, as a dependent tx, this freed descriptor trigger
BUG_ON(async_tx_test_ack(depend_tx)) in async_tx_submit().

TASK = ee1a94a0[1390] 'md0_raid5' THREAD: ecf40000 CPU: 0
GPR00: 00000001 ecf41ca0 ee44/921a94a0 0000003f 00000001 c00593e4 00000000 00000001
GPR08: 00000000 a7a7a7a7 00000001 045/920000002 42028042 100a38d4 ed576d98 00000000
GPR16: ed5a11b0 00000000 2b162000 00000200 046/920000000 2d555000 ed3015e8 c15a7aa0
GPR24: 00000000 c155fc40 00000000 ecb63220 ecf41d28 e47/92f640bb0 ef640c30 ecf41ca0
NIP [c02b048c] async_tx_submit+0x6c/0x2b4
LR [c02b068c] async_tx_submit+0x26c/0x2b4
Call Trace:
[ecf41ca0] [c02b068c] async_tx_submit+0x26c/0x2b448/92 (unreliable)
[ecf41cd0] [c02b0a4c] async_memcpy+0x240/0x25c
[ecf41d20] [c0421064] async_copy_data+0xa0/0x17c
[ecf41d70] [c0421cf4] __raid_run_ops+0x874/0xe10
[ecf41df0] [c0426ee4] handle_stripe+0x820/0x25e8
[ecf41e90] [c0429080] raid5d+0x3d4/0x5b4
[ecf41f40] [c04329b8] md_thread+0x138/0x16c
[ecf41f90] [c008277c] kthread+0x8c/0x90
[ecf41ff0] [c0011630] kernel_thread+0x4c/0x68

Another modification in this patch is the change of completed descriptors,
there is a potential risk which caused by exception interrupt, all descriptors
in ld_running list are seemed completed when an interrupt raised, it works fine
under normal condition, but if there is an exception occured, it cannot work as
our excepted. Hardware should not be depend on s/w list, the right way is to
read current descriptor address register to find the last completed descriptor.
If an interrupt is raised by an error, all descriptors in ld_running should not
be seemed finished, or these unfinished descriptors in ld_running will be
released wrongly.

A simple way to reproduce:
Enable dmatest first, then insert some bad descriptors which can trigger
Programming Error interrupts before the good descriptors. Last, the good
descriptors will be freed before they are processsed because of the exception
intrerrupt.

Note: the bad descriptors are only for simulating an exception interrupt.  This
case can illustrate the potential risk in current fsl-dma very well.

Signed-off-by: Hongbo Zhang <hongbo.zhang@freescale.com>
Signed-off-by: Qiang Liu <qiang.liu@freescale.com>
Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
---
 drivers/dma/fsldma.c |  195 ++++++++++++++++++++++++++++++++++++--------------
 drivers/dma/fsldma.h |   17 ++++-
 2 files changed, 158 insertions(+), 54 deletions(-)

diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index 968877f..f8eee60 100644
--- a/drivers/dma/fsldma.c
+++ b/drivers/dma/fsldma.c
@@ -459,6 +459,87 @@ static struct fsl_desc_sw *fsl_dma_alloc_descriptor(struct fsldma_chan *chan)
 }
 
 /**
+ * fsldma_clean_completed_descriptor - free all descriptors which
+ * has been completed and acked
+ * @chan: Freescale DMA channel
+ *
+ * This function is used on all completed and acked descriptors.
+ * All descriptors should only be freed in this function.
+ */
+static void fsldma_clean_completed_descriptor(struct fsldma_chan *chan)
+{
+	struct fsl_desc_sw *desc, *_desc;
+
+	/* Run the callback for each descriptor, in order */
+	list_for_each_entry_safe(desc, _desc, &chan->ld_completed, node)
+		if (async_tx_test_ack(&desc->async_tx))
+			fsl_dma_free_descriptor(chan, desc);
+}
+
+/**
+ * fsldma_run_tx_complete_actions - cleanup a single link descriptor
+ * @chan: Freescale DMA channel
+ * @desc: descriptor to cleanup and free
+ * @cookie: Freescale DMA transaction identifier
+ *
+ * This function is used on a descriptor which has been executed by the DMA
+ * controller. It will run any callbacks, submit any dependencies.
+ */
+static dma_cookie_t fsldma_run_tx_complete_actions(struct fsldma_chan *chan,
+		struct fsl_desc_sw *desc, dma_cookie_t cookie)
+{
+	struct dma_async_tx_descriptor *txd = &desc->async_tx;
+
+	BUG_ON(txd->cookie < 0);
+
+	if (txd->cookie > 0) {
+		cookie = txd->cookie;
+
+		/* Run the link descriptor callback function */
+		if (txd->callback) {
+			chan_dbg(chan, "LD %p callback\n", desc);
+			txd->callback(txd->callback_param);
+		}
+	}
+
+	/* Run any dependencies */
+	dma_run_dependencies(txd);
+
+	return cookie;
+}
+
+/**
+ * fsldma_clean_running_descriptor - move the completed descriptor from
+ * ld_running to ld_completed
+ * @chan: Freescale DMA channel
+ * @desc: the descriptor which is completed
+ *
+ * Free the descriptor directly if acked by async_tx api, or move it to
+ * queue ld_completed.
+ */
+static void fsldma_clean_running_descriptor(struct fsldma_chan *chan,
+		struct fsl_desc_sw *desc)
+{
+	/* Remove from the list of transactions */
+	list_del(&desc->node);
+
+	/*
+	 * the client is allowed to attach dependent operations
+	 * until 'ack' is set
+	 */
+	if (!async_tx_test_ack(&desc->async_tx)) {
+		/*
+		 * Move this descriptor to the list of descriptors which is
+		 * completed, but still awaiting the 'ack' bit to be set.
+		 */
+		list_add_tail(&desc->node, &chan->ld_completed);
+		return;
+	}
+
+	dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
+}
+
+/**
  * fsl_chan_xfer_ld_queue - transfer any pending transactions
  * @chan : Freescale DMA channel
  *
@@ -526,30 +607,58 @@ static void fsl_chan_xfer_ld_queue(struct fsldma_chan *chan)
 }
 
 /**
- * fsldma_cleanup_descriptor - cleanup and free a single link descriptor
+ * fsldma_cleanup_descriptors - cleanup link descriptors which are completed
+ * and move them to ld_completed to free until flag 'ack' is set
  * @chan: Freescale DMA channel
- * @desc: descriptor to cleanup and free
  *
- * This function is used on a descriptor which has been executed by the DMA
- * controller. It will run any callbacks, submit any dependencies, and then
- * free the descriptor.
+ * This function is used on descriptors which have been executed by the DMA
+ * controller. It will run any callbacks, submit any dependencies, then
+ * free these descriptors if flag 'ack' is set.
  */
-static void fsldma_cleanup_descriptor(struct fsldma_chan *chan,
-				      struct fsl_desc_sw *desc)
+static void fsldma_cleanup_descriptors(struct fsldma_chan *chan)
 {
-	struct dma_async_tx_descriptor *txd = &desc->async_tx;
+	struct fsl_desc_sw *desc, *_desc;
+	dma_cookie_t cookie = 0;
+	dma_addr_t curr_phys = get_cdar(chan);
+	int seen_current = 0;
+
+	fsldma_clean_completed_descriptor(chan);
+
+	/* Run the callback for each descriptor, in order */
+	list_for_each_entry_safe(desc, _desc, &chan->ld_running, node) {
+		/*
+		 * do not advance past the current descriptor loaded into the
+		 * hardware channel, subsequent descriptors are either in
+		 * process or have not been submitted
+		 */
+		if (seen_current)
+			break;
+
+		/*
+		 * stop the search if we reach the current descriptor and the
+		 * channel is busy
+		 */
+		if (desc->async_tx.phys == curr_phys) {
+			seen_current = 1;
+			if (!dma_is_idle(chan))
+				break;
+		}
+
+		cookie = fsldma_run_tx_complete_actions(chan, desc, cookie);
 
-	/* Run the link descriptor callback function */
-	if (txd->callback) {
-		chan_dbg(chan, "LD %p callback\n", desc);
-		txd->callback(txd->callback_param);
+		fsldma_clean_running_descriptor(chan, desc);
 	}
 
-	/* Run any dependencies */
-	dma_run_dependencies(txd);
+	/*
+	 * Start any pending transactions automatically
+	 *
+	 * In the ideal case, we keep the DMA controller busy while we go
+	 * ahead and free the descriptors below.
+	 */
+	fsl_chan_xfer_ld_queue(chan);
 
-	dma_descriptor_unmap(txd);
-	fsl_dma_free_descriptor(chan, desc);
+	if (cookie > 0)
+		chan->common.completed_cookie = cookie;
 }
 
 /**
@@ -620,8 +729,10 @@ static void fsl_dma_free_chan_resources(struct dma_chan *dchan)
 
 	chan_dbg(chan, "free all channel resources\n");
 	spin_lock_irqsave(&chan->desc_lock, flags);
+	fsldma_cleanup_descriptors(chan);
 	fsldma_free_desc_list(chan, &chan->ld_pending);
 	fsldma_free_desc_list(chan, &chan->ld_running);
+	fsldma_free_desc_list(chan, &chan->ld_completed);
 	spin_unlock_irqrestore(&chan->desc_lock, flags);
 
 	dma_pool_destroy(chan->desc_pool);
@@ -859,6 +970,7 @@ static int fsl_dma_device_control(struct dma_chan *dchan,
 		/* Remove and free all of the descriptors in the LD queue */
 		fsldma_free_desc_list(chan, &chan->ld_pending);
 		fsldma_free_desc_list(chan, &chan->ld_running);
+		fsldma_free_desc_list(chan, &chan->ld_completed);
 		chan->idle = true;
 
 		spin_unlock_irqrestore(&chan->desc_lock, flags);
@@ -918,6 +1030,17 @@ static enum dma_status fsl_tx_status(struct dma_chan *dchan,
 					dma_cookie_t cookie,
 					struct dma_tx_state *txstate)
 {
+	struct fsldma_chan *chan = to_fsl_chan(dchan);
+	enum dma_status ret;
+
+	ret = dma_cookie_status(dchan, cookie, txstate);
+	if (ret == DMA_COMPLETE)
+		return ret;
+
+	spin_lock_bh(&chan->desc_lock);
+	fsldma_cleanup_descriptors(chan);
+	spin_unlock_bh(&chan->desc_lock);
+
 	return dma_cookie_status(dchan, cookie, txstate);
 }
 
@@ -995,52 +1118,19 @@ static irqreturn_t fsldma_chan_irq(int irq, void *data)
 static void dma_do_tasklet(unsigned long data)
 {
 	struct fsldma_chan *chan = (struct fsldma_chan *)data;
-	struct fsl_desc_sw *desc, *_desc;
-	LIST_HEAD(ld_cleanup);
 	unsigned long flags;
 
 	chan_dbg(chan, "tasklet entry\n");
 
 	spin_lock_irqsave(&chan->desc_lock, flags);
 
-	/* update the cookie if we have some descriptors to cleanup */
-	if (!list_empty(&chan->ld_running)) {
-		dma_cookie_t cookie;
-
-		desc = to_fsl_desc(chan->ld_running.prev);
-		cookie = desc->async_tx.cookie;
-		dma_cookie_complete(&desc->async_tx);
-
-		chan_dbg(chan, "completed_cookie=%d\n", cookie);
-	}
-
-	/*
-	 * move the descriptors to a temporary list so we can drop the lock
-	 * during the entire cleanup operation
-	 */
-	list_splice_tail_init(&chan->ld_running, &ld_cleanup);
-
 	/* the hardware is now idle and ready for more */
 	chan->idle = true;
 
-	/*
-	 * Start any pending transactions automatically
-	 *
-	 * In the ideal case, we keep the DMA controller busy while we go
-	 * ahead and free the descriptors below.
-	 */
-	fsl_chan_xfer_ld_queue(chan);
-	spin_unlock_irqrestore(&chan->desc_lock, flags);
+	/* Run all cleanup for descriptors which have been completed */
+	fsldma_cleanup_descriptors(chan);
 
-	/* Run the callback for each descriptor, in order */
-	list_for_each_entry_safe(desc, _desc, &ld_cleanup, node) {
-
-		/* Remove from the list of transactions */
-		list_del(&desc->node);
-
-		/* Run all cleanup for this descriptor */
-		fsldma_cleanup_descriptor(chan, desc);
-	}
+	spin_unlock_irqrestore(&chan->desc_lock, flags);
 
 	chan_dbg(chan, "tasklet exit\n");
 }
@@ -1224,6 +1314,7 @@ static int fsl_dma_chan_probe(struct fsldma_device *fdev,
 	spin_lock_init(&chan->desc_lock);
 	INIT_LIST_HEAD(&chan->ld_pending);
 	INIT_LIST_HEAD(&chan->ld_running);
+	INIT_LIST_HEAD(&chan->ld_completed);
 	chan->idle = true;
 
 	chan->common.device = &fdev->common;
diff --git a/drivers/dma/fsldma.h b/drivers/dma/fsldma.h
index d56e835..ec19517 100644
--- a/drivers/dma/fsldma.h
+++ b/drivers/dma/fsldma.h
@@ -138,8 +138,21 @@ struct fsldma_chan {
 	char name[8];			/* Channel name */
 	struct fsldma_chan_regs __iomem *regs;
 	spinlock_t desc_lock;		/* Descriptor operation lock */
-	struct list_head ld_pending;	/* Link descriptors queue */
-	struct list_head ld_running;	/* Link descriptors queue */
+	/*
+	 * Descriptors which are queued to run, but have not yet been
+	 * submitted to the hardware for execution
+	 */
+	struct list_head ld_pending;
+	/*
+	 * Descriptors which are currently being executed by the hardware
+	 */
+	struct list_head ld_running;
+	/*
+	 * Descriptors which have finished execution by the hardware. These
+	 * descriptors have already had their cleanup actions run. They are
+	 * waiting for the ACK bit to be set by the async_tx API.
+	 */
+	struct list_head ld_completed;	/* Link descriptors queue */
 	struct dma_chan common;		/* DMA common channel */
 	struct dma_pool *desc_pool;	/* Descriptors pool */
 	struct device *dev;		/* Channel device */
-- 
1.7.9.5

Re: [PATCH v3 6/8] DMA: Freescale: change descriptor release process for supporting async_tx

[Andy Shevchenko]

On Thu, 2014-04-10 at 15:10 +0800, hongbo.zhang@freescale.com wrote:
> From: Hongbo Zhang <hongbo.zhang@freescale.com>
> 
> Fix the potential risk when enable config NET_DMA and ASYNC_TX. Async_tx is
> lack of support in current release process of dma descriptor, all descriptors
> will be released whatever is acked or no-acked by async_tx, so there is a
> potential race condition when dma engine is uesd by others clients (e.g. when
> enable NET_DMA to offload TCP).
> 
> In our case, a race condition which is raised when use both of talitos and
> dmaengine to offload xor is because napi scheduler will sync all pending
> requests in dma channels, it affects the process of raid operations due to
> ack_tx is not checked in fsl dma. The no-acked descriptor is freed which is
> submitted just now, as a dependent tx, this freed descriptor trigger
> BUG_ON(async_tx_test_ack(depend_tx)) in async_tx_submit().
> 
> TASK = ee1a94a0[1390] 'md0_raid5' THREAD: ecf40000 CPU: 0
> GPR00: 00000001 ecf41ca0 ee44/921a94a0 0000003f 00000001 c00593e4 00000000 00000001
> GPR08: 00000000 a7a7a7a7 00000001 045/920000002 42028042 100a38d4 ed576d98 00000000
> GPR16: ed5a11b0 00000000 2b162000 00000200 046/920000000 2d555000 ed3015e8 c15a7aa0
> GPR24: 00000000 c155fc40 00000000 ecb63220 ecf41d28 e47/92f640bb0 ef640c30 ecf41ca0
> NIP [c02b048c] async_tx_submit+0x6c/0x2b4
> LR [c02b068c] async_tx_submit+0x26c/0x2b4
> Call Trace:
> [ecf41ca0] [c02b068c] async_tx_submit+0x26c/0x2b448/92 (unreliable)
> [ecf41cd0] [c02b0a4c] async_memcpy+0x240/0x25c
> [ecf41d20] [c0421064] async_copy_data+0xa0/0x17c
> [ecf41d70] [c0421cf4] __raid_run_ops+0x874/0xe10
> [ecf41df0] [c0426ee4] handle_stripe+0x820/0x25e8
> [ecf41e90] [c0429080] raid5d+0x3d4/0x5b4
> [ecf41f40] [c04329b8] md_thread+0x138/0x16c
> [ecf41f90] [c008277c] kthread+0x8c/0x90
> [ecf41ff0] [c0011630] kernel_thread+0x4c/0x68
> 
> Another modification in this patch is the change of completed descriptors,
> there is a potential risk which caused by exception interrupt, all descriptors
> in ld_running list are seemed completed when an interrupt raised, it works fine
> under normal condition, but if there is an exception occured, it cannot work as
> our excepted. Hardware should not be depend on s/w list, the right way is to
> read current descriptor address register to find the last completed descriptor.
> If an interrupt is raised by an error, all descriptors in ld_running should not
> be seemed finished, or these unfinished descriptors in ld_running will be
> released wrongly.
> 
> A simple way to reproduce:
> Enable dmatest first, then insert some bad descriptors which can trigger
> Programming Error interrupts before the good descriptors. Last, the good
> descriptors will be freed before they are processsed because of the exception
> intrerrupt.
> 
> Note: the bad descriptors are only for simulating an exception interrupt.  This
> case can illustrate the potential risk in current fsl-dma very well.
> 
> Signed-off-by: Hongbo Zhang <hongbo.zhang@freescale.com>
> Signed-off-by: Qiang Liu <qiang.liu@freescale.com>
> Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
> ---
>  drivers/dma/fsldma.c |  195 ++++++++++++++++++++++++++++++++++++--------------
>  drivers/dma/fsldma.h |   17 ++++-
>  2 files changed, 158 insertions(+), 54 deletions(-)
> 
> diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
> index 968877f..f8eee60 100644
> --- a/drivers/dma/fsldma.c
> +++ b/drivers/dma/fsldma.c
> @@ -459,6 +459,87 @@ static struct fsl_desc_sw *fsl_dma_alloc_descriptor(struct fsldma_chan *chan)
>  }
>  
>  /**
> + * fsldma_clean_completed_descriptor - free all descriptors which
> + * has been completed and acked

IIRC the summary should be oneliner.
Check the rest of the code as well.

> + * @chan: Freescale DMA channel
> + *
> + * This function is used on all completed and acked descriptors.
> + * All descriptors should only be freed in this function.
> + */
> +static void fsldma_clean_completed_descriptor(struct fsldma_chan *chan)
> +{
> +	struct fsl_desc_sw *desc, *_desc;
> +
> +	/* Run the callback for each descriptor, in order */
> +	list_for_each_entry_safe(desc, _desc, &chan->ld_completed, node)
> +		if (async_tx_test_ack(&desc->async_tx))
> +			fsl_dma_free_descriptor(chan, desc);
> +}
> +
> +/**
> + * fsldma_run_tx_complete_actions - cleanup a single link descriptor
> + * @chan: Freescale DMA channel
> + * @desc: descriptor to cleanup and free
> + * @cookie: Freescale DMA transaction identifier
> + *
> + * This function is used on a descriptor which has been executed by the DMA
> + * controller. It will run any callbacks, submit any dependencies.
> + */
> +static dma_cookie_t fsldma_run_tx_complete_actions(struct fsldma_chan *chan,
> +		struct fsl_desc_sw *desc, dma_cookie_t cookie)

Maybe you could use cookie as local variable?

> +{
> +	struct dma_async_tx_descriptor *txd = &desc->async_tx;
> +
> +	BUG_ON(txd->cookie < 0);
> +
> +	if (txd->cookie > 0) {
> +		cookie = txd->cookie;
> +
> +		/* Run the link descriptor callback function */
> +		if (txd->callback) {
> +			chan_dbg(chan, "LD %p callback\n", desc);
> +			txd->callback(txd->callback_param);
> +		}
> +	}
> +
> +	/* Run any dependencies */
> +	dma_run_dependencies(txd);
> +
> +	return cookie;
> +}
> +
> +/**
> + * fsldma_clean_running_descriptor - move the completed descriptor from
> + * ld_running to ld_completed
> + * @chan: Freescale DMA channel
> + * @desc: the descriptor which is completed
> + *
> + * Free the descriptor directly if acked by async_tx api, or move it to
> + * queue ld_completed.
> + */
> +static void fsldma_clean_running_descriptor(struct fsldma_chan *chan,
> +		struct fsl_desc_sw *desc)
> +{
> +	/* Remove from the list of transactions */
> +	list_del(&desc->node);
> +
> +	/*
> +	 * the client is allowed to attach dependent operations

Capital letter first?

> +	 * until 'ack' is set
> +	 */
> +	if (!async_tx_test_ack(&desc->async_tx)) {
> +		/*
> +		 * Move this descriptor to the list of descriptors which is
> +		 * completed, but still awaiting the 'ack' bit to be set.
> +		 */
> +		list_add_tail(&desc->node, &chan->ld_completed);
> +		return;
> +	}
> +
> +	dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
> +}
> +
> +/**
>   * fsl_chan_xfer_ld_queue - transfer any pending transactions
>   * @chan : Freescale DMA channel
>   *
> @@ -526,30 +607,58 @@ static void fsl_chan_xfer_ld_queue(struct fsldma_chan *chan)
>  }
>  
>  /**
> - * fsldma_cleanup_descriptor - cleanup and free a single link descriptor
> + * fsldma_cleanup_descriptors - cleanup link descriptors which are completed
> + * and move them to ld_completed to free until flag 'ack' is set
>   * @chan: Freescale DMA channel
> - * @desc: descriptor to cleanup and free
>   *
> - * This function is used on a descriptor which has been executed by the DMA
> - * controller. It will run any callbacks, submit any dependencies, and then
> - * free the descriptor.
> + * This function is used on descriptors which have been executed by the DMA
> + * controller. It will run any callbacks, submit any dependencies, then
> + * free these descriptors if flag 'ack' is set.
>   */
> -static void fsldma_cleanup_descriptor(struct fsldma_chan *chan,
> -				      struct fsl_desc_sw *desc)
> +static void fsldma_cleanup_descriptors(struct fsldma_chan *chan)
>  {
> -	struct dma_async_tx_descriptor *txd = &desc->async_tx;
> +	struct fsl_desc_sw *desc, *_desc;
> +	dma_cookie_t cookie = 0;
> +	dma_addr_t curr_phys = get_cdar(chan);
> +	int seen_current = 0;
> +
> +	fsldma_clean_completed_descriptor(chan);
> +
> +	/* Run the callback for each descriptor, in order */
> +	list_for_each_entry_safe(desc, _desc, &chan->ld_running, node) {
> +		/*
> +		 * do not advance past the current descriptor loaded into the

Capital letter first.

> +		 * hardware channel, subsequent descriptors are either in
> +		 * process or have not been submitted

Dot at the eol. Check in all comments.

> +		 */
> +		if (seen_current)
> +			break;
> +
> +		/*
> +		 * stop the search if we reach the current descriptor and the
> +		 * channel is busy
> +		 */
> +		if (desc->async_tx.phys == curr_phys) {
> +			seen_current = 1;
> +			if (!dma_is_idle(chan))
> +				break;
> +		}
> +
> +		cookie = fsldma_run_tx_complete_actions(chan, desc, cookie);
>  
> -	/* Run the link descriptor callback function */
> -	if (txd->callback) {
> -		chan_dbg(chan, "LD %p callback\n", desc);
> -		txd->callback(txd->callback_param);
> +		fsldma_clean_running_descriptor(chan, desc);
>  	}
>  
> -	/* Run any dependencies */
> -	dma_run_dependencies(txd);
> +	/*
> +	 * Start any pending transactions automatically

Dot at the end of the line.

> +	 *
> +	 * In the ideal case, we keep the DMA controller busy while we go
> +	 * ahead and free the descriptors below.
> +	 */
> +	fsl_chan_xfer_ld_queue(chan);
>  
> -	dma_descriptor_unmap(txd);
> -	fsl_dma_free_descriptor(chan, desc);
> +	if (cookie > 0)


> +		chan->common.completed_cookie = cookie;
>  }
>  
>  /**
> @@ -620,8 +729,10 @@ static void fsl_dma_free_chan_resources(struct dma_chan *dchan)
>  
>  	chan_dbg(chan, "free all channel resources\n");
>  	spin_lock_irqsave(&chan->desc_lock, flags);
> +	fsldma_cleanup_descriptors(chan);
>  	fsldma_free_desc_list(chan, &chan->ld_pending);
>  	fsldma_free_desc_list(chan, &chan->ld_running);
> +	fsldma_free_desc_list(chan, &chan->ld_completed);
>  	spin_unlock_irqrestore(&chan->desc_lock, flags);
>  
>  	dma_pool_destroy(chan->desc_pool);
> @@ -859,6 +970,7 @@ static int fsl_dma_device_control(struct dma_chan *dchan,
>  		/* Remove and free all of the descriptors in the LD queue */
>  		fsldma_free_desc_list(chan, &chan->ld_pending);
>  		fsldma_free_desc_list(chan, &chan->ld_running);
> +		fsldma_free_desc_list(chan, &chan->ld_completed);
>  		chan->idle = true;
>  
>  		spin_unlock_irqrestore(&chan->desc_lock, flags);
> @@ -918,6 +1030,17 @@ static enum dma_status fsl_tx_status(struct dma_chan *dchan,
>  					dma_cookie_t cookie,
>  					struct dma_tx_state *txstate)
>  {
> +	struct fsldma_chan *chan = to_fsl_chan(dchan);
> +	enum dma_status ret;
> +
> +	ret = dma_cookie_status(dchan, cookie, txstate);
> +	if (ret == DMA_COMPLETE)
> +		return ret;
> +
> +	spin_lock_bh(&chan->desc_lock);
> +	fsldma_cleanup_descriptors(chan);
> +	spin_unlock_bh(&chan->desc_lock);
> +
>  	return dma_cookie_status(dchan, cookie, txstate);
>  }
>  
> @@ -995,52 +1118,19 @@ static irqreturn_t fsldma_chan_irq(int irq, void *data)
>  static void dma_do_tasklet(unsigned long data)
>  {
>  	struct fsldma_chan *chan = (struct fsldma_chan *)data;
> -	struct fsl_desc_sw *desc, *_desc;
> -	LIST_HEAD(ld_cleanup);
>  	unsigned long flags;
>  
>  	chan_dbg(chan, "tasklet entry\n");
>  
>  	spin_lock_irqsave(&chan->desc_lock, flags);
>  
> -	/* update the cookie if we have some descriptors to cleanup */
> -	if (!list_empty(&chan->ld_running)) {
> -		dma_cookie_t cookie;
> -
> -		desc = to_fsl_desc(chan->ld_running.prev);
> -		cookie = desc->async_tx.cookie;
> -		dma_cookie_complete(&desc->async_tx);
> -
> -		chan_dbg(chan, "completed_cookie=%d\n", cookie);
> -	}
> -
> -	/*
> -	 * move the descriptors to a temporary list so we can drop the lock
> -	 * during the entire cleanup operation
> -	 */
> -	list_splice_tail_init(&chan->ld_running, &ld_cleanup);
> -
>  	/* the hardware is now idle and ready for more */
>  	chan->idle = true;
>  
> -	/*
> -	 * Start any pending transactions automatically
> -	 *
> -	 * In the ideal case, we keep the DMA controller busy while we go
> -	 * ahead and free the descriptors below.
> -	 */
> -	fsl_chan_xfer_ld_queue(chan);
> -	spin_unlock_irqrestore(&chan->desc_lock, flags);
> +	/* Run all cleanup for descriptors which have been completed */
> +	fsldma_cleanup_descriptors(chan);
>  
> -	/* Run the callback for each descriptor, in order */
> -	list_for_each_entry_safe(desc, _desc, &ld_cleanup, node) {
> -
> -		/* Remove from the list of transactions */
> -		list_del(&desc->node);
> -
> -		/* Run all cleanup for this descriptor */
> -		fsldma_cleanup_descriptor(chan, desc);
> -	}
> +	spin_unlock_irqrestore(&chan->desc_lock, flags);
>  
>  	chan_dbg(chan, "tasklet exit\n");
>  }
> @@ -1224,6 +1314,7 @@ static int fsl_dma_chan_probe(struct fsldma_device *fdev,
>  	spin_lock_init(&chan->desc_lock);
>  	INIT_LIST_HEAD(&chan->ld_pending);
>  	INIT_LIST_HEAD(&chan->ld_running);
> +	INIT_LIST_HEAD(&chan->ld_completed);
>  	chan->idle = true;
>  
>  	chan->common.device = &fdev->common;
> diff --git a/drivers/dma/fsldma.h b/drivers/dma/fsldma.h
> index d56e835..ec19517 100644
> --- a/drivers/dma/fsldma.h
> +++ b/drivers/dma/fsldma.h
> @@ -138,8 +138,21 @@ struct fsldma_chan {
>  	char name[8];			/* Channel name */
>  	struct fsldma_chan_regs __iomem *regs;
>  	spinlock_t desc_lock;		/* Descriptor operation lock */
> -	struct list_head ld_pending;	/* Link descriptors queue */
> -	struct list_head ld_running;	/* Link descriptors queue */
> +	/*
> +	 * Descriptors which are queued to run, but have not yet been
> +	 * submitted to the hardware for execution
> +	 */
> +	struct list_head ld_pending;
> +	/*
> +	 * Descriptors which are currently being executed by the hardware
> +	 */
> +	struct list_head ld_running;
> +	/*
> +	 * Descriptors which have finished execution by the hardware. These
> +	 * descriptors have already had their cleanup actions run. They are
> +	 * waiting for the ACK bit to be set by the async_tx API.
> +	 */
> +	struct list_head ld_completed;	/* Link descriptors queue */
>  	struct dma_chan common;		/* DMA common channel */
>  	struct dma_pool *desc_pool;	/* Descriptors pool */
>  	struct device *dev;		/* Channel device */


-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

Re: [PATCH v3 6/8] DMA: Freescale: change descriptor release process for supporting async_tx

[Hongbo Zhang]

On 04/10/2014 07:56 PM, Andy Shevchenko wrote:
> On Thu, 2014-04-10 at 15:10 +0800, hongbo.zhang@freescale.com wrote:
>> From: Hongbo Zhang <hongbo.zhang@freescale.com>
>>
>> Fix the potential risk when enable config NET_DMA and ASYNC_TX. Async_tx is
>> lack of support in current release process of dma descriptor, all descriptors
>> will be released whatever is acked or no-acked by async_tx, so there is a
>> potential race condition when dma engine is uesd by others clients (e.g. when
>> enable NET_DMA to offload TCP).
>>
>> In our case, a race condition which is raised when use both of talitos and
>> dmaengine to offload xor is because napi scheduler will sync all pending
>> requests in dma channels, it affects the process of raid operations due to
>> ack_tx is not checked in fsl dma. The no-acked descriptor is freed which is
>> submitted just now, as a dependent tx, this freed descriptor trigger
>> BUG_ON(async_tx_test_ack(depend_tx)) in async_tx_submit().
>>
>> TASK = ee1a94a0[1390] 'md0_raid5' THREAD: ecf40000 CPU: 0
>> GPR00: 00000001 ecf41ca0 ee44/921a94a0 0000003f 00000001 c00593e4 00000000 00000001
>> GPR08: 00000000 a7a7a7a7 00000001 045/920000002 42028042 100a38d4 ed576d98 00000000
>> GPR16: ed5a11b0 00000000 2b162000 00000200 046/920000000 2d555000 ed3015e8 c15a7aa0
>> GPR24: 00000000 c155fc40 00000000 ecb63220 ecf41d28 e47/92f640bb0 ef640c30 ecf41ca0
>> NIP [c02b048c] async_tx_submit+0x6c/0x2b4
>> LR [c02b068c] async_tx_submit+0x26c/0x2b4
>> Call Trace:
>> [ecf41ca0] [c02b068c] async_tx_submit+0x26c/0x2b448/92 (unreliable)
>> [ecf41cd0] [c02b0a4c] async_memcpy+0x240/0x25c
>> [ecf41d20] [c0421064] async_copy_data+0xa0/0x17c
>> [ecf41d70] [c0421cf4] __raid_run_ops+0x874/0xe10
>> [ecf41df0] [c0426ee4] handle_stripe+0x820/0x25e8
>> [ecf41e90] [c0429080] raid5d+0x3d4/0x5b4
>> [ecf41f40] [c04329b8] md_thread+0x138/0x16c
>> [ecf41f90] [c008277c] kthread+0x8c/0x90
>> [ecf41ff0] [c0011630] kernel_thread+0x4c/0x68
>>
>> Another modification in this patch is the change of completed descriptors,
>> there is a potential risk which caused by exception interrupt, all descriptors
>> in ld_running list are seemed completed when an interrupt raised, it works fine
>> under normal condition, but if there is an exception occured, it cannot work as
>> our excepted. Hardware should not be depend on s/w list, the right way is to
>> read current descriptor address register to find the last completed descriptor.
>> If an interrupt is raised by an error, all descriptors in ld_running should not
>> be seemed finished, or these unfinished descriptors in ld_running will be
>> released wrongly.
>>
>> A simple way to reproduce:
>> Enable dmatest first, then insert some bad descriptors which can trigger
>> Programming Error interrupts before the good descriptors. Last, the good
>> descriptors will be freed before they are processsed because of the exception
>> intrerrupt.
>>
>> Note: the bad descriptors are only for simulating an exception interrupt.  This
>> case can illustrate the potential risk in current fsl-dma very well.
>>
>> Signed-off-by: Hongbo Zhang <hongbo.zhang@freescale.com>
>> Signed-off-by: Qiang Liu <qiang.liu@freescale.com>
>> Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
>> ---
>>   drivers/dma/fsldma.c |  195 ++++++++++++++++++++++++++++++++++++--------------
>>   drivers/dma/fsldma.h |   17 ++++-
>>   2 files changed, 158 insertions(+), 54 deletions(-)
>>
>> diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
>> index 968877f..f8eee60 100644
>> --- a/drivers/dma/fsldma.c
>> +++ b/drivers/dma/fsldma.c
>> @@ -459,6 +459,87 @@ static struct fsl_desc_sw *fsl_dma_alloc_descriptor(struct fsldma_chan *chan)
>>   }
>>   
>>   /**
>> + * fsldma_clean_completed_descriptor - free all descriptors which
>> + * has been completed and acked
> IIRC the summary should be oneliner.
> Check the rest of the code as well.

I don't think so.
See this Documentation/kernel-doc-nano-HOWTO.txt, and you can find this 
sentence "The short description following the subject can span multiple 
lines"

>> + * @chan: Freescale DMA channel
>> + *
>> + * This function is used on all completed and acked descriptors.
>> + * All descriptors should only be freed in this function.
>> + */
>> +static void fsldma_clean_completed_descriptor(struct fsldma_chan *chan)
>> +{
>> +	struct fsl_desc_sw *desc, *_desc;
>> +
>> +	/* Run the callback for each descriptor, in order */
>> +	list_for_each_entry_safe(desc, _desc, &chan->ld_completed, node)
>> +		if (async_tx_test_ack(&desc->async_tx))
>> +			fsl_dma_free_descriptor(chan, desc);
>> +}
>> +
>> +/**
>> + * fsldma_run_tx_complete_actions - cleanup a single link descriptor
>> + * @chan: Freescale DMA channel
>> + * @desc: descriptor to cleanup and free
>> + * @cookie: Freescale DMA transaction identifier
>> + *
>> + * This function is used on a descriptor which has been executed by the DMA
>> + * controller. It will run any callbacks, submit any dependencies.
>> + */
>> +static dma_cookie_t fsldma_run_tx_complete_actions(struct fsldma_chan *chan,
>> +		struct fsl_desc_sw *desc, dma_cookie_t cookie)
> Maybe you could use cookie as local variable?

Yes.. it doesn't seem good to set a value to input parameter.

>> +{
>> +	struct dma_async_tx_descriptor *txd = &desc->async_tx;
>> +
>> +	BUG_ON(txd->cookie < 0);
>> +
>> +	if (txd->cookie > 0) {
>> +		cookie = txd->cookie;
>> +
>> +		/* Run the link descriptor callback function */
>> +		if (txd->callback) {
>> +			chan_dbg(chan, "LD %p callback\n", desc);
>> +			txd->callback(txd->callback_param);
>> +		}
>> +	}
>> +
>> +	/* Run any dependencies */
>> +	dma_run_dependencies(txd);
>> +
>> +	return cookie;
>> +}
>> +
>> +/**
>> + * fsldma_clean_running_descriptor - move the completed descriptor from
>> + * ld_running to ld_completed
>> + * @chan: Freescale DMA channel
>> + * @desc: the descriptor which is completed
>> + *
>> + * Free the descriptor directly if acked by async_tx api, or move it to
>> + * queue ld_completed.
>> + */
>> +static void fsldma_clean_running_descriptor(struct fsldma_chan *chan,
>> +		struct fsl_desc_sw *desc)
>> +{
>> +	/* Remove from the list of transactions */
>> +	list_del(&desc->node);
>> +
>> +	/*
>> +	 * the client is allowed to attach dependent operations
> Capital letter first?

Better to do so, thanks.

>> +	 * until 'ack' is set
>> +	 */
>> +	if (!async_tx_test_ack(&desc->async_tx)) {
>> +		/*
>> +		 * Move this descriptor to the list of descriptors which is
>> +		 * completed, but still awaiting the 'ack' bit to be set.
>> +		 */
>> +		list_add_tail(&desc->node, &chan->ld_completed);
>> +		return;
>> +	}
>> +
>> +	dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
>> +}
>> +
>> +/**
>>    * fsl_chan_xfer_ld_queue - transfer any pending transactions
>>    * @chan : Freescale DMA channel
>>    *
>> @@ -526,30 +607,58 @@ static void fsl_chan_xfer_ld_queue(struct fsldma_chan *chan)
>>   }
>>   
>>   /**
>> - * fsldma_cleanup_descriptor - cleanup and free a single link descriptor
>> + * fsldma_cleanup_descriptors - cleanup link descriptors which are completed
>> + * and move them to ld_completed to free until flag 'ack' is set
>>    * @chan: Freescale DMA channel
>> - * @desc: descriptor to cleanup and free
>>    *
>> - * This function is used on a descriptor which has been executed by the DMA
>> - * controller. It will run any callbacks, submit any dependencies, and then
>> - * free the descriptor.
>> + * This function is used on descriptors which have been executed by the DMA
>> + * controller. It will run any callbacks, submit any dependencies, then
>> + * free these descriptors if flag 'ack' is set.
>>    */
>> -static void fsldma_cleanup_descriptor(struct fsldma_chan *chan,
>> -				      struct fsl_desc_sw *desc)
>> +static void fsldma_cleanup_descriptors(struct fsldma_chan *chan)
>>   {
>> -	struct dma_async_tx_descriptor *txd = &desc->async_tx;
>> +	struct fsl_desc_sw *desc, *_desc;
>> +	dma_cookie_t cookie = 0;
>> +	dma_addr_t curr_phys = get_cdar(chan);
>> +	int seen_current = 0;
>> +
>> +	fsldma_clean_completed_descriptor(chan);
>> +
>> +	/* Run the callback for each descriptor, in order */
>> +	list_for_each_entry_safe(desc, _desc, &chan->ld_running, node) {
>> +		/*
>> +		 * do not advance past the current descriptor loaded into the
> Capital letter first.
>
>> +		 * hardware channel, subsequent descriptors are either in
>> +		 * process or have not been submitted
> Dot at the eol. Check in all comments.

Even though I saw there are other comments without the dots, I think it 
is better to have it.
Thanks, all.

>
>> +		 */
>> +		if (seen_current)
>> +			break;
>> +
>> +		/*
>> +		 * stop the search if we reach the current descriptor and the
>> +		 * channel is busy
>> +		 */
>> +		if (desc->async_tx.phys == curr_phys) {
>> +			seen_current = 1;
>> +			if (!dma_is_idle(chan))
>> +				break;
>> +		}
>> +
>> +		cookie = fsldma_run_tx_complete_actions(chan, desc, cookie);
>>   
>> -	/* Run the link descriptor callback function */
>> -	if (txd->callback) {
>> -		chan_dbg(chan, "LD %p callback\n", desc);
>> -		txd->callback(txd->callback_param);
>> +		fsldma_clean_running_descriptor(chan, desc);
>>   	}
>>   
>> -	/* Run any dependencies */
>> -	dma_run_dependencies(txd);
>> +	/*
>> +	 * Start any pending transactions automatically
> Dot at the end of the line.
>
>> +	 *
>> +	 * In the ideal case, we keep the DMA controller busy while we go
>> +	 * ahead and free the descriptors below.
>> +	 */
>> +	fsl_chan_xfer_ld_queue(chan);
>>   
>> -	dma_descriptor_unmap(txd);
>> -	fsl_dma_free_descriptor(chan, desc);
>> +	if (cookie > 0)
>
>> +		chan->common.completed_cookie = cookie;
>>   }
>>   
>>   /**
>> @@ -620,8 +729,10 @@ static void fsl_dma_free_chan_resources(struct dma_chan *dchan)
>>   
>>   	chan_dbg(chan, "free all channel resources\n");
>>   	spin_lock_irqsave(&chan->desc_lock, flags);
>> +	fsldma_cleanup_descriptors(chan);
>>   	fsldma_free_desc_list(chan, &chan->ld_pending);
>>   	fsldma_free_desc_list(chan, &chan->ld_running);
>> +	fsldma_free_desc_list(chan, &chan->ld_completed);
>>   	spin_unlock_irqrestore(&chan->desc_lock, flags);
>>   
>>   	dma_pool_destroy(chan->desc_pool);
>> @@ -859,6 +970,7 @@ static int fsl_dma_device_control(struct dma_chan *dchan,
>>   		/* Remove and free all of the descriptors in the LD queue */
>>   		fsldma_free_desc_list(chan, &chan->ld_pending);
>>   		fsldma_free_desc_list(chan, &chan->ld_running);
>> +		fsldma_free_desc_list(chan, &chan->ld_completed);
>>   		chan->idle = true;
>>   
>>   		spin_unlock_irqrestore(&chan->desc_lock, flags);
>> @@ -918,6 +1030,17 @@ static enum dma_status fsl_tx_status(struct dma_chan *dchan,
>>   					dma_cookie_t cookie,
>>   					struct dma_tx_state *txstate)
>>   {
>> +	struct fsldma_chan *chan = to_fsl_chan(dchan);
>> +	enum dma_status ret;
>> +
>> +	ret = dma_cookie_status(dchan, cookie, txstate);
>> +	if (ret == DMA_COMPLETE)
>> +		return ret;
>> +
>> +	spin_lock_bh(&chan->desc_lock);
>> +	fsldma_cleanup_descriptors(chan);
>> +	spin_unlock_bh(&chan->desc_lock);
>> +
>>   	return dma_cookie_status(dchan, cookie, txstate);
>>   }
>>   
>> @@ -995,52 +1118,19 @@ static irqreturn_t fsldma_chan_irq(int irq, void *data)
>>   static void dma_do_tasklet(unsigned long data)
>>   {
>>   	struct fsldma_chan *chan = (struct fsldma_chan *)data;
>> -	struct fsl_desc_sw *desc, *_desc;
>> -	LIST_HEAD(ld_cleanup);
>>   	unsigned long flags;
>>   
>>   	chan_dbg(chan, "tasklet entry\n");
>>   
>>   	spin_lock_irqsave(&chan->desc_lock, flags);
>>   
>> -	/* update the cookie if we have some descriptors to cleanup */
>> -	if (!list_empty(&chan->ld_running)) {
>> -		dma_cookie_t cookie;
>> -
>> -		desc = to_fsl_desc(chan->ld_running.prev);
>> -		cookie = desc->async_tx.cookie;
>> -		dma_cookie_complete(&desc->async_tx);
>> -
>> -		chan_dbg(chan, "completed_cookie=%d\n", cookie);
>> -	}
>> -
>> -	/*
>> -	 * move the descriptors to a temporary list so we can drop the lock
>> -	 * during the entire cleanup operation
>> -	 */
>> -	list_splice_tail_init(&chan->ld_running, &ld_cleanup);
>> -
>>   	/* the hardware is now idle and ready for more */
>>   	chan->idle = true;
>>   
>> -	/*
>> -	 * Start any pending transactions automatically
>> -	 *
>> -	 * In the ideal case, we keep the DMA controller busy while we go
>> -	 * ahead and free the descriptors below.
>> -	 */
>> -	fsl_chan_xfer_ld_queue(chan);
>> -	spin_unlock_irqrestore(&chan->desc_lock, flags);
>> +	/* Run all cleanup for descriptors which have been completed */
>> +	fsldma_cleanup_descriptors(chan);
>>   
>> -	/* Run the callback for each descriptor, in order */
>> -	list_for_each_entry_safe(desc, _desc, &ld_cleanup, node) {
>> -
>> -		/* Remove from the list of transactions */
>> -		list_del(&desc->node);
>> -
>> -		/* Run all cleanup for this descriptor */
>> -		fsldma_cleanup_descriptor(chan, desc);
>> -	}
>> +	spin_unlock_irqrestore(&chan->desc_lock, flags);
>>   
>>   	chan_dbg(chan, "tasklet exit\n");
>>   }
>> @@ -1224,6 +1314,7 @@ static int fsl_dma_chan_probe(struct fsldma_device *fdev,
>>   	spin_lock_init(&chan->desc_lock);
>>   	INIT_LIST_HEAD(&chan->ld_pending);
>>   	INIT_LIST_HEAD(&chan->ld_running);
>> +	INIT_LIST_HEAD(&chan->ld_completed);
>>   	chan->idle = true;
>>   
>>   	chan->common.device = &fdev->common;
>> diff --git a/drivers/dma/fsldma.h b/drivers/dma/fsldma.h
>> index d56e835..ec19517 100644
>> --- a/drivers/dma/fsldma.h
>> +++ b/drivers/dma/fsldma.h
>> @@ -138,8 +138,21 @@ struct fsldma_chan {
>>   	char name[8];			/* Channel name */
>>   	struct fsldma_chan_regs __iomem *regs;
>>   	spinlock_t desc_lock;		/* Descriptor operation lock */
>> -	struct list_head ld_pending;	/* Link descriptors queue */
>> -	struct list_head ld_running;	/* Link descriptors queue */
>> +	/*
>> +	 * Descriptors which are queued to run, but have not yet been
>> +	 * submitted to the hardware for execution
>> +	 */
>> +	struct list_head ld_pending;
>> +	/*
>> +	 * Descriptors which are currently being executed by the hardware
>> +	 */
>> +	struct list_head ld_running;
>> +	/*
>> +	 * Descriptors which have finished execution by the hardware. These
>> +	 * descriptors have already had their cleanup actions run. They are
>> +	 * waiting for the ACK bit to be set by the async_tx API.
>> +	 */
>> +	struct list_head ld_completed;	/* Link descriptors queue */
>>   	struct dma_chan common;		/* DMA common channel */
>>   	struct dma_pool *desc_pool;	/* Descriptors pool */
>>   	struct device *dev;		/* Channel device */
>

Re: [PATCH v3 6/8] DMA: Freescale: change descriptor release process for supporting async_tx

[Hongbo Zhang]

On 04/11/2014 04:00 PM, Hongbo Zhang wrote:
>
> On 04/10/2014 07:56 PM, Andy Shevchenko wrote:
>> On Thu, 2014-04-10 at 15:10 +0800, hongbo.zhang@freescale.com wrote:
>>> From: Hongbo Zhang <hongbo.zhang@freescale.com>
>>>
>>> Fix the potential risk when enable config NET_DMA and ASYNC_TX. 
>>> Async_tx is
>>> lack of support in current release process of dma descriptor, all 
>>> descriptors
>>> will be released whatever is acked or no-acked by async_tx, so there 
>>> is a
>>> potential race condition when dma engine is uesd by others clients 
>>> (e.g. when
>>> enable NET_DMA to offload TCP).
>>>
>>> In our case, a race condition which is raised when use both of 
>>> talitos and
>>> dmaengine to offload xor is because napi scheduler will sync all 
>>> pending
>>> requests in dma channels, it affects the process of raid operations 
>>> due to
>>> ack_tx is not checked in fsl dma. The no-acked descriptor is freed 
>>> which is
>>> submitted just now, as a dependent tx, this freed descriptor trigger
>>> BUG_ON(async_tx_test_ack(depend_tx)) in async_tx_submit().
>>>
>>> TASK = ee1a94a0[1390] 'md0_raid5' THREAD: ecf40000 CPU: 0
>>> GPR00: 00000001 ecf41ca0 ee44/921a94a0 0000003f 00000001 c00593e4 
>>> 00000000 00000001
>>> GPR08: 00000000 a7a7a7a7 00000001 045/920000002 42028042 100a38d4 
>>> ed576d98 00000000
>>> GPR16: ed5a11b0 00000000 2b162000 00000200 046/920000000 2d555000 
>>> ed3015e8 c15a7aa0
>>> GPR24: 00000000 c155fc40 00000000 ecb63220 ecf41d28 e47/92f640bb0 
>>> ef640c30 ecf41ca0
>>> NIP [c02b048c] async_tx_submit+0x6c/0x2b4
>>> LR [c02b068c] async_tx_submit+0x26c/0x2b4
>>> Call Trace:
>>> [ecf41ca0] [c02b068c] async_tx_submit+0x26c/0x2b448/92 (unreliable)
>>> [ecf41cd0] [c02b0a4c] async_memcpy+0x240/0x25c
>>> [ecf41d20] [c0421064] async_copy_data+0xa0/0x17c
>>> [ecf41d70] [c0421cf4] __raid_run_ops+0x874/0xe10
>>> [ecf41df0] [c0426ee4] handle_stripe+0x820/0x25e8
>>> [ecf41e90] [c0429080] raid5d+0x3d4/0x5b4
>>> [ecf41f40] [c04329b8] md_thread+0x138/0x16c
>>> [ecf41f90] [c008277c] kthread+0x8c/0x90
>>> [ecf41ff0] [c0011630] kernel_thread+0x4c/0x68
>>>
>>> Another modification in this patch is the change of completed 
>>> descriptors,
>>> there is a potential risk which caused by exception interrupt, all 
>>> descriptors
>>> in ld_running list are seemed completed when an interrupt raised, it 
>>> works fine
>>> under normal condition, but if there is an exception occured, it 
>>> cannot work as
>>> our excepted. Hardware should not be depend on s/w list, the right 
>>> way is to
>>> read current descriptor address register to find the last completed 
>>> descriptor.
>>> If an interrupt is raised by an error, all descriptors in ld_running 
>>> should not
>>> be seemed finished, or these unfinished descriptors in ld_running 
>>> will be
>>> released wrongly.
>>>
>>> A simple way to reproduce:
>>> Enable dmatest first, then insert some bad descriptors which can 
>>> trigger
>>> Programming Error interrupts before the good descriptors. Last, the 
>>> good
>>> descriptors will be freed before they are processsed because of the 
>>> exception
>>> intrerrupt.
>>>
>>> Note: the bad descriptors are only for simulating an exception 
>>> interrupt.  This
>>> case can illustrate the potential risk in current fsl-dma very well.
>>>
>>> Signed-off-by: Hongbo Zhang <hongbo.zhang@freescale.com>
>>> Signed-off-by: Qiang Liu <qiang.liu@freescale.com>
>>> Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
>>> ---
>>>   drivers/dma/fsldma.c |  195 
>>> ++++++++++++++++++++++++++++++++++++--------------
>>>   drivers/dma/fsldma.h |   17 ++++-
>>>   2 files changed, 158 insertions(+), 54 deletions(-)
>>>
>>> diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
>>> index 968877f..f8eee60 100644
>>> --- a/drivers/dma/fsldma.c
>>> +++ b/drivers/dma/fsldma.c
>>> @@ -459,6 +459,87 @@ static struct fsl_desc_sw 
>>> *fsl_dma_alloc_descriptor(struct fsldma_chan *chan)
>>>   }
>>>     /**
>>> + * fsldma_clean_completed_descriptor - free all descriptors which
>>> + * has been completed and acked
>> IIRC the summary should be oneliner.
>> Check the rest of the code as well.
>
> I don't think so.
> See this Documentation/kernel-doc-nano-HOWTO.txt, and you can find 
> this sentence "The short description following the subject can span 
> multiple lines"
>
>>> + * @chan: Freescale DMA channel
>>> + *
>>> + * This function is used on all completed and acked descriptors.
>>> + * All descriptors should only be freed in this function.
>>> + */
>>> +static void fsldma_clean_completed_descriptor(struct fsldma_chan 
>>> *chan)
>>> +{
>>> +    struct fsl_desc_sw *desc, *_desc;
>>> +
>>> +    /* Run the callback for each descriptor, in order */
>>> +    list_for_each_entry_safe(desc, _desc, &chan->ld_completed, node)
>>> +        if (async_tx_test_ack(&desc->async_tx))
>>> +            fsl_dma_free_descriptor(chan, desc);
>>> +}
>>> +
>>> +/**
>>> + * fsldma_run_tx_complete_actions - cleanup a single link descriptor
>>> + * @chan: Freescale DMA channel
>>> + * @desc: descriptor to cleanup and free
>>> + * @cookie: Freescale DMA transaction identifier
>>> + *
>>> + * This function is used on a descriptor which has been executed by 
>>> the DMA
>>> + * controller. It will run any callbacks, submit any dependencies.
>>> + */
>>> +static dma_cookie_t fsldma_run_tx_complete_actions(struct 
>>> fsldma_chan *chan,
>>> +        struct fsl_desc_sw *desc, dma_cookie_t cookie)
>> Maybe you could use cookie as local variable?
>
> Yes.. it doesn't seem good to set a value to input parameter.
>
>>> +{
>>> +    struct dma_async_tx_descriptor *txd = &desc->async_tx;
>>> +
>>> +    BUG_ON(txd->cookie < 0);
>>> +
>>> +    if (txd->cookie > 0) {
>>> +        cookie = txd->cookie;
>>> +
>>> +        /* Run the link descriptor callback function */
>>> +        if (txd->callback) {
>>> +            chan_dbg(chan, "LD %p callback\n", desc);
>>> +            txd->callback(txd->callback_param);
>>> +        }
>>> +    }
>>> +
>>> +    /* Run any dependencies */
>>> +    dma_run_dependencies(txd);
>>> +
>>> +    return cookie;
>>> +}
>>> +
>>> +/**
>>> + * fsldma_clean_running_descriptor - move the completed descriptor 
>>> from
>>> + * ld_running to ld_completed
>>> + * @chan: Freescale DMA channel
>>> + * @desc: the descriptor which is completed
>>> + *
>>> + * Free the descriptor directly if acked by async_tx api, or move 
>>> it to
>>> + * queue ld_completed.
>>> + */
>>> +static void fsldma_clean_running_descriptor(struct fsldma_chan *chan,
>>> +        struct fsl_desc_sw *desc)
>>> +{
>>> +    /* Remove from the list of transactions */
>>> +    list_del(&desc->node);
>>> +
>>> +    /*
>>> +     * the client is allowed to attach dependent operations
>> Capital letter first?
>
> Better to do so, thanks.
>
>>> +     * until 'ack' is set
>>> +     */
>>> +    if (!async_tx_test_ack(&desc->async_tx)) {
>>> +        /*
>>> +         * Move this descriptor to the list of descriptors which is
>>> +         * completed, but still awaiting the 'ack' bit to be set.
>>> +         */
>>> +        list_add_tail(&desc->node, &chan->ld_completed);
>>> +        return;
>>> +    }
>>> +
>>> +    dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
>>> +}
>>> +
>>> +/**
>>>    * fsl_chan_xfer_ld_queue - transfer any pending transactions
>>>    * @chan : Freescale DMA channel
>>>    *
>>> @@ -526,30 +607,58 @@ static void fsl_chan_xfer_ld_queue(struct 
>>> fsldma_chan *chan)
>>>   }
>>>     /**
>>> - * fsldma_cleanup_descriptor - cleanup and free a single link 
>>> descriptor
>>> + * fsldma_cleanup_descriptors - cleanup link descriptors which are 
>>> completed
>>> + * and move them to ld_completed to free until flag 'ack' is set
>>>    * @chan: Freescale DMA channel
>>> - * @desc: descriptor to cleanup and free
>>>    *
>>> - * This function is used on a descriptor which has been executed by 
>>> the DMA
>>> - * controller. It will run any callbacks, submit any dependencies, 
>>> and then
>>> - * free the descriptor.
>>> + * This function is used on descriptors which have been executed by 
>>> the DMA
>>> + * controller. It will run any callbacks, submit any dependencies, 
>>> then
>>> + * free these descriptors if flag 'ack' is set.
>>>    */
>>> -static void fsldma_cleanup_descriptor(struct fsldma_chan *chan,
>>> -                      struct fsl_desc_sw *desc)
>>> +static void fsldma_cleanup_descriptors(struct fsldma_chan *chan)
>>>   {
>>> -    struct dma_async_tx_descriptor *txd = &desc->async_tx;
>>> +    struct fsl_desc_sw *desc, *_desc;
>>> +    dma_cookie_t cookie = 0;
>>> +    dma_addr_t curr_phys = get_cdar(chan);
>>> +    int seen_current = 0;
>>> +
>>> +    fsldma_clean_completed_descriptor(chan);
>>> +
>>> +    /* Run the callback for each descriptor, in order */
>>> +    list_for_each_entry_safe(desc, _desc, &chan->ld_running, node) {
>>> +        /*
>>> +         * do not advance past the current descriptor loaded into the
>> Capital letter first.
>>
>>> +         * hardware channel, subsequent descriptors are either in
>>> +         * process or have not been submitted
>> Dot at the eol. Check in all comments.
>
> Even though I saw there are other comments without the dots, I think 
> it is better to have it.
> Thanks, all.
>
Hmm... think it again, it it really necessary to have it?
Even I have it in my patch, there are already so many comments exists 
without it.

>>
>>> +         */
>>> +        if (seen_current)
>>> +            break;
>>> +
>>> +        /*
>>> +         * stop the search if we reach the current descriptor and the
>>> +         * channel is busy
>>> +         */
>>> +        if (desc->async_tx.phys == curr_phys) {
>>> +            seen_current = 1;
>>> +            if (!dma_is_idle(chan))
>>> +                break;
>>> +        }
>>> +
>>> +        cookie = fsldma_run_tx_complete_actions(chan, desc, cookie);
>>>   -    /* Run the link descriptor callback function */
>>> -    if (txd->callback) {
>>> -        chan_dbg(chan, "LD %p callback\n", desc);
>>> -        txd->callback(txd->callback_param);
>>> +        fsldma_clean_running_descriptor(chan, desc);
>>>       }
>>>   -    /* Run any dependencies */
>>> -    dma_run_dependencies(txd);
>>> +    /*
>>> +     * Start any pending transactions automatically
>> Dot at the end of the line.
>>
>>> +     *
>>> +     * In the ideal case, we keep the DMA controller busy while we go
>>> +     * ahead and free the descriptors below.
>>> +     */
>>> +    fsl_chan_xfer_ld_queue(chan);
>>>   -    dma_descriptor_unmap(txd);
>>> -    fsl_dma_free_descriptor(chan, desc);
>>> +    if (cookie > 0)
>>
>>> + chan->common.completed_cookie = cookie;
>>>   }
>>>     /**
>>> @@ -620,8 +729,10 @@ static void fsl_dma_free_chan_resources(struct 
>>> dma_chan *dchan)
>>>         chan_dbg(chan, "free all channel resources\n");
>>>       spin_lock_irqsave(&chan->desc_lock, flags);
>>> +    fsldma_cleanup_descriptors(chan);
>>>       fsldma_free_desc_list(chan, &chan->ld_pending);
>>>       fsldma_free_desc_list(chan, &chan->ld_running);
>>> +    fsldma_free_desc_list(chan, &chan->ld_completed);
>>>       spin_unlock_irqrestore(&chan->desc_lock, flags);
>>>         dma_pool_destroy(chan->desc_pool);
>>> @@ -859,6 +970,7 @@ static int fsl_dma_device_control(struct 
>>> dma_chan *dchan,
>>>           /* Remove and free all of the descriptors in the LD queue */
>>>           fsldma_free_desc_list(chan, &chan->ld_pending);
>>>           fsldma_free_desc_list(chan, &chan->ld_running);
>>> +        fsldma_free_desc_list(chan, &chan->ld_completed);
>>>           chan->idle = true;
>>>             spin_unlock_irqrestore(&chan->desc_lock, flags);
>>> @@ -918,6 +1030,17 @@ static enum dma_status fsl_tx_status(struct 
>>> dma_chan *dchan,
>>>                       dma_cookie_t cookie,
>>>                       struct dma_tx_state *txstate)
>>>   {
>>> +    struct fsldma_chan *chan = to_fsl_chan(dchan);
>>> +    enum dma_status ret;
>>> +
>>> +    ret = dma_cookie_status(dchan, cookie, txstate);
>>> +    if (ret == DMA_COMPLETE)
>>> +        return ret;
>>> +
>>> +    spin_lock_bh(&chan->desc_lock);
>>> +    fsldma_cleanup_descriptors(chan);
>>> +    spin_unlock_bh(&chan->desc_lock);
>>> +
>>>       return dma_cookie_status(dchan, cookie, txstate);
>>>   }
>>>   @@ -995,52 +1118,19 @@ static irqreturn_t fsldma_chan_irq(int irq, 
>>> void *data)
>>>   static void dma_do_tasklet(unsigned long data)
>>>   {
>>>       struct fsldma_chan *chan = (struct fsldma_chan *)data;
>>> -    struct fsl_desc_sw *desc, *_desc;
>>> -    LIST_HEAD(ld_cleanup);
>>>       unsigned long flags;
>>>         chan_dbg(chan, "tasklet entry\n");
>>>         spin_lock_irqsave(&chan->desc_lock, flags);
>>>   -    /* update the cookie if we have some descriptors to cleanup */
>>> -    if (!list_empty(&chan->ld_running)) {
>>> -        dma_cookie_t cookie;
>>> -
>>> -        desc = to_fsl_desc(chan->ld_running.prev);
>>> -        cookie = desc->async_tx.cookie;
>>> -        dma_cookie_complete(&desc->async_tx);
>>> -
>>> -        chan_dbg(chan, "completed_cookie=%d\n", cookie);
>>> -    }
>>> -
>>> -    /*
>>> -     * move the descriptors to a temporary list so we can drop the 
>>> lock
>>> -     * during the entire cleanup operation
>>> -     */
>>> -    list_splice_tail_init(&chan->ld_running, &ld_cleanup);
>>> -
>>>       /* the hardware is now idle and ready for more */
>>>       chan->idle = true;
>>>   -    /*
>>> -     * Start any pending transactions automatically
>>> -     *
>>> -     * In the ideal case, we keep the DMA controller busy while we go
>>> -     * ahead and free the descriptors below.
>>> -     */
>>> -    fsl_chan_xfer_ld_queue(chan);
>>> -    spin_unlock_irqrestore(&chan->desc_lock, flags);
>>> +    /* Run all cleanup for descriptors which have been completed */
>>> +    fsldma_cleanup_descriptors(chan);
>>>   -    /* Run the callback for each descriptor, in order */
>>> -    list_for_each_entry_safe(desc, _desc, &ld_cleanup, node) {
>>> -
>>> -        /* Remove from the list of transactions */
>>> -        list_del(&desc->node);
>>> -
>>> -        /* Run all cleanup for this descriptor */
>>> -        fsldma_cleanup_descriptor(chan, desc);
>>> -    }
>>> +    spin_unlock_irqrestore(&chan->desc_lock, flags);
>>>         chan_dbg(chan, "tasklet exit\n");
>>>   }
>>> @@ -1224,6 +1314,7 @@ static int fsl_dma_chan_probe(struct 
>>> fsldma_device *fdev,
>>>       spin_lock_init(&chan->desc_lock);
>>>       INIT_LIST_HEAD(&chan->ld_pending);
>>>       INIT_LIST_HEAD(&chan->ld_running);
>>> +    INIT_LIST_HEAD(&chan->ld_completed);
>>>       chan->idle = true;
>>>         chan->common.device = &fdev->common;
>>> diff --git a/drivers/dma/fsldma.h b/drivers/dma/fsldma.h
>>> index d56e835..ec19517 100644
>>> --- a/drivers/dma/fsldma.h
>>> +++ b/drivers/dma/fsldma.h
>>> @@ -138,8 +138,21 @@ struct fsldma_chan {
>>>       char name[8];            /* Channel name */
>>>       struct fsldma_chan_regs __iomem *regs;
>>>       spinlock_t desc_lock;        /* Descriptor operation lock */
>>> -    struct list_head ld_pending;    /* Link descriptors queue */
>>> -    struct list_head ld_running;    /* Link descriptors queue */
>>> +    /*
>>> +     * Descriptors which are queued to run, but have not yet been
>>> +     * submitted to the hardware for execution
>>> +     */
>>> +    struct list_head ld_pending;
>>> +    /*
>>> +     * Descriptors which are currently being executed by the hardware
>>> +     */
>>> +    struct list_head ld_running;
>>> +    /*
>>> +     * Descriptors which have finished execution by the hardware. 
>>> These
>>> +     * descriptors have already had their cleanup actions run. They 
>>> are
>>> +     * waiting for the ACK bit to be set by the async_tx API.
>>> +     */
>>> +    struct list_head ld_completed;    /* Link descriptors queue */
>>>       struct dma_chan common;        /* DMA common channel */
>>>       struct dma_pool *desc_pool;    /* Descriptors pool */
>>>       struct device *dev;        /* Channel device */
>>
>

Re: [PATCH v3 6/8] DMA: Freescale: change descriptor release process for supporting async_tx

[Andy Shevchenko]

On Fri, 2014-04-11 at 16:33 +0800, Hongbo Zhang wrote:

> >>> +         * hardware channel, subsequent descriptors are either in
> >>> +         * process or have not been submitted
> >> Dot at the eol. Check in all comments.
> >
> > Even though I saw there are other comments without the dots, I think 
> > it is better to have it.
> > Thanks, all.
> >
> Hmm... think it again, it it really necessary to have it?
> Even I have it in my patch, there are already so many comments exists 
> without it.

For my opinion is better to keep style in your patches. Better if it
commonly used style in the driver. But comment against comments is
really minor thing.

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

[PATCH v3 7/8] DMA: Freescale: use spin_lock_bh instead of spin_lock_irqsave

[hongbo.zhang]

From: Hongbo Zhang <hongbo.zhang@freescale.com>

The usage of spin_lock_irqsave() is a stronger locking mechanism than is
required throughout the driver. The minimum locking required should be used
instead. Interrupts will be turned off and context will be saved, it is
unnecessary to use irqsave.

This patch changes all instances of spin_lock_irqsave() to spin_lock_bh(). All
manipulation of protected fields is done using tasklet context or weaker, which
makes spin_lock_bh() the correct choice.

Signed-off-by: Hongbo Zhang <hongbo.zhang@freescale.com>
Signed-off-by: Qiang Liu <qiang.liu@freescale.com>
---
 drivers/dma/fsldma.c |   25 ++++++++++---------------
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index f8eee60..c9bf54a 100644
--- a/drivers/dma/fsldma.c
+++ b/drivers/dma/fsldma.c
@@ -396,10 +396,9 @@ static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx)
 	struct fsldma_chan *chan = to_fsl_chan(tx->chan);
 	struct fsl_desc_sw *desc = tx_to_fsl_desc(tx);
 	struct fsl_desc_sw *child;
-	unsigned long flags;
 	dma_cookie_t cookie = -EINVAL;
 
-	spin_lock_irqsave(&chan->desc_lock, flags);
+	spin_lock_bh(&chan->desc_lock);
 
 	/*
 	 * assign cookies to all of the software descriptors
@@ -412,7 +411,7 @@ static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx)
 	/* put this transaction onto the tail of the pending queue */
 	append_ld_queue(chan, desc);
 
-	spin_unlock_irqrestore(&chan->desc_lock, flags);
+	spin_unlock_bh(&chan->desc_lock);
 
 	return cookie;
 }
@@ -725,15 +724,14 @@ static void fsldma_free_desc_list_reverse(struct fsldma_chan *chan,
 static void fsl_dma_free_chan_resources(struct dma_chan *dchan)
 {
 	struct fsldma_chan *chan = to_fsl_chan(dchan);
-	unsigned long flags;
 
 	chan_dbg(chan, "free all channel resources\n");
-	spin_lock_irqsave(&chan->desc_lock, flags);
+	spin_lock_bh(&chan->desc_lock);
 	fsldma_cleanup_descriptors(chan);
 	fsldma_free_desc_list(chan, &chan->ld_pending);
 	fsldma_free_desc_list(chan, &chan->ld_running);
 	fsldma_free_desc_list(chan, &chan->ld_completed);
-	spin_unlock_irqrestore(&chan->desc_lock, flags);
+	spin_unlock_bh(&chan->desc_lock);
 
 	dma_pool_destroy(chan->desc_pool);
 	chan->desc_pool = NULL;
@@ -952,7 +950,6 @@ static int fsl_dma_device_control(struct dma_chan *dchan,
 {
 	struct dma_slave_config *config;
 	struct fsldma_chan *chan;
-	unsigned long flags;
 	int size;
 
 	if (!dchan)
@@ -962,7 +959,7 @@ static int fsl_dma_device_control(struct dma_chan *dchan,
 
 	switch (cmd) {
 	case DMA_TERMINATE_ALL:
-		spin_lock_irqsave(&chan->desc_lock, flags);
+		spin_lock_bh(&chan->desc_lock);
 
 		/* Halt the DMA engine */
 		dma_halt(chan);
@@ -973,7 +970,7 @@ static int fsl_dma_device_control(struct dma_chan *dchan,
 		fsldma_free_desc_list(chan, &chan->ld_completed);
 		chan->idle = true;
 
-		spin_unlock_irqrestore(&chan->desc_lock, flags);
+		spin_unlock_bh(&chan->desc_lock);
 		return 0;
 
 	case DMA_SLAVE_CONFIG:
@@ -1015,11 +1012,10 @@ static int fsl_dma_device_control(struct dma_chan *dchan,
 static void fsl_dma_memcpy_issue_pending(struct dma_chan *dchan)
 {
 	struct fsldma_chan *chan = to_fsl_chan(dchan);
-	unsigned long flags;
 
-	spin_lock_irqsave(&chan->desc_lock, flags);
+	spin_lock_bh(&chan->desc_lock);
 	fsl_chan_xfer_ld_queue(chan);
-	spin_unlock_irqrestore(&chan->desc_lock, flags);
+	spin_unlock_bh(&chan->desc_lock);
 }
 
 /**
@@ -1118,11 +1114,10 @@ static irqreturn_t fsldma_chan_irq(int irq, void *data)
 static void dma_do_tasklet(unsigned long data)
 {
 	struct fsldma_chan *chan = (struct fsldma_chan *)data;
-	unsigned long flags;
 
 	chan_dbg(chan, "tasklet entry\n");
 
-	spin_lock_irqsave(&chan->desc_lock, flags);
+	spin_lock_bh(&chan->desc_lock);
 
 	/* the hardware is now idle and ready for more */
 	chan->idle = true;
@@ -1130,7 +1125,7 @@ static void dma_do_tasklet(unsigned long data)
 	/* Run all cleanup for descriptors which have been completed */
 	fsldma_cleanup_descriptors(chan);
 
-	spin_unlock_irqrestore(&chan->desc_lock, flags);
+	spin_unlock_bh(&chan->desc_lock);
 
 	chan_dbg(chan, "tasklet exit\n");
 }
-- 
1.7.9.5

[PATCH v3 8/8] DMA: Freescale: add suspend resume functions for DMA driver

[hongbo.zhang]

From: Hongbo Zhang <hongbo.zhang@freescale.com>

This patch adds suspend resume functions for Freescale DMA driver.
.prepare callback is used to stop further descriptors from being added into the
pending queue, and also issue pending queues into execution if there is any.
.suspend callback makes sure all the pending jobs are cleaned up and all the
channels are idle, and save the mode registers.
.resume callback re-initializes the channels by restore the mode registers.

Signed-off-by: Hongbo Zhang <hongbo.zhang@freescale.com>
---
 drivers/dma/fsldma.c |  100 ++++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/dma/fsldma.h |   16 ++++++++
 2 files changed, 116 insertions(+)

diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index c9bf54a..d6da222 100644
--- a/drivers/dma/fsldma.c
+++ b/drivers/dma/fsldma.c
@@ -400,6 +400,14 @@ static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx)
 
 	spin_lock_bh(&chan->desc_lock);
 
+#ifdef CONFIG_PM
+	if (unlikely(chan->pm_state != RUNNING)) {
+		chan_dbg(chan, "cannot submit due to suspend\n");
+		spin_unlock_bh(&chan->desc_lock);
+		return -1;
+	}
+#endif
+
 	/*
 	 * assign cookies to all of the software descriptors
 	 * that make up this transaction
@@ -1311,6 +1319,9 @@ static int fsl_dma_chan_probe(struct fsldma_device *fdev,
 	INIT_LIST_HEAD(&chan->ld_running);
 	INIT_LIST_HEAD(&chan->ld_completed);
 	chan->idle = true;
+#ifdef CONFIG_PM
+	chan->pm_state = RUNNING;
+#endif
 
 	chan->common.device = &fdev->common;
 	dma_cookie_init(&chan->common);
@@ -1450,6 +1461,92 @@ static int fsldma_of_remove(struct platform_device *op)
 	return 0;
 }
 
+#ifdef CONFIG_PM
+static int fsldma_prepare(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct fsldma_device *fdev = platform_get_drvdata(pdev);
+	struct fsldma_chan *chan;
+	int i;
+
+	for (i = 0; i < FSL_DMA_MAX_CHANS_PER_DEVICE; i++) {
+		chan = fdev->chan[i];
+		if (!chan)
+			continue;
+
+		spin_lock_bh(&chan->desc_lock);
+		chan->pm_state = SUSPENDING;
+		if (!list_empty(&chan->ld_pending))
+			fsl_chan_xfer_ld_queue(chan);
+		spin_unlock_bh(&chan->desc_lock);
+	}
+
+	return 0;
+}
+
+static int fsldma_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct fsldma_device *fdev = platform_get_drvdata(pdev);
+	struct fsldma_chan *chan;
+	int i;
+
+	for (i = 0; i < FSL_DMA_MAX_CHANS_PER_DEVICE; i++) {
+		chan = fdev->chan[i];
+		if (!chan)
+			continue;
+
+		spin_lock_bh(&chan->desc_lock);
+		if (!chan->idle)
+			goto out;
+		chan->regs_save.mr = DMA_IN(chan, &chan->regs->mr, 32);
+		chan->pm_state = SUSPENDED;
+		spin_unlock_bh(&chan->desc_lock);
+	}
+	return 0;
+
+out:
+	for (; i >= 0; i--) {
+		chan = fdev->chan[i];
+		if (!chan)
+			continue;
+		chan->pm_state = RUNNING;
+		spin_unlock_bh(&chan->desc_lock);
+	}
+	return -EBUSY;
+}
+
+static int fsldma_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct fsldma_device *fdev = platform_get_drvdata(pdev);
+	struct fsldma_chan *chan;
+	u32 mode;
+	int i;
+
+	for (i = 0; i < FSL_DMA_MAX_CHANS_PER_DEVICE; i++) {
+		chan = fdev->chan[i];
+		if (!chan)
+			continue;
+
+		spin_lock_bh(&chan->desc_lock);
+		mode = chan->regs_save.mr
+			& ~FSL_DMA_MR_CS & ~FSL_DMA_MR_CC & ~FSL_DMA_MR_CA;
+		DMA_OUT(chan, &chan->regs->mr, mode, 32);
+		chan->pm_state = RUNNING;
+		spin_unlock_bh(&chan->desc_lock);
+	}
+
+	return 0;
+}
+
+static const struct dev_pm_ops fsldma_pm_ops = {
+	.prepare	= fsldma_prepare,
+	.suspend	= fsldma_suspend,
+	.resume		= fsldma_resume,
+};
+#endif
+
 static const struct of_device_id fsldma_of_ids[] = {
 	{ .compatible = "fsl,elo3-dma", },
 	{ .compatible = "fsl,eloplus-dma", },
@@ -1462,6 +1559,9 @@ static struct platform_driver fsldma_of_driver = {
 		.name = "fsl-elo-dma",
 		.owner = THIS_MODULE,
 		.of_match_table = fsldma_of_ids,
+#ifdef CONFIG_PM
+		.pm = &fsldma_pm_ops,
+#endif
 	},
 	.probe = fsldma_of_probe,
 	.remove = fsldma_of_remove,
diff --git a/drivers/dma/fsldma.h b/drivers/dma/fsldma.h
index ec19517..eecaf9e 100644
--- a/drivers/dma/fsldma.h
+++ b/drivers/dma/fsldma.h
@@ -134,6 +134,18 @@ struct fsldma_device {
 #define FSL_DMA_CHAN_PAUSE_EXT	0x00001000
 #define FSL_DMA_CHAN_START_EXT	0x00002000
 
+#ifdef CONFIG_PM
+struct fsldma_chan_regs_save {
+	u32 mr;
+};
+
+enum fsldma_pm_state {
+	RUNNING = 0,
+	SUSPENDING,
+	SUSPENDED,
+};
+#endif
+
 struct fsldma_chan {
 	char name[8];			/* Channel name */
 	struct fsldma_chan_regs __iomem *regs;
@@ -161,6 +173,10 @@ struct fsldma_chan {
 	struct tasklet_struct tasklet;
 	u32 feature;
 	bool idle;			/* DMA controller is idle */
+#ifdef CONFIG_PM
+	struct fsldma_chan_regs_save regs_save;
+	enum fsldma_pm_state pm_state;
+#endif
 
 	void (*toggle_ext_pause)(struct fsldma_chan *fsl_chan, int enable);
 	void (*toggle_ext_start)(struct fsldma_chan *fsl_chan, int enable);
-- 
1.7.9.5

Re: [PATCH v3 8/8] DMA: Freescale: add suspend resume functions for DMA driver

[Andy Shevchenko]

On Thu, 2014-04-10 at 15:10 +0800, hongbo.zhang@freescale.com wrote:
> From: Hongbo Zhang <hongbo.zhang@freescale.com>
> 
> This patch adds suspend resume functions for Freescale DMA driver.
> .prepare callback is used to stop further descriptors from being added into the
> pending queue, and also issue pending queues into execution if there is any.
> .suspend callback makes sure all the pending jobs are cleaned up and all the
> channels are idle, and save the mode registers.
> .resume callback re-initializes the channels by restore the mode registers.

Like we discussed with Vinod [1] the DMA controller drivers should go to
suspend after users and come back before them.

After you reconsider this point the patch logic might be modified a lot.

(Moreover, you abuse your own position to use only setters/getters to
access to the DMAc registers)

[1] http://www.spinics.net/lists/kernel/msg1650974.html


> 
> Signed-off-by: Hongbo Zhang <hongbo.zhang@freescale.com>
> ---
>  drivers/dma/fsldma.c |  100 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/dma/fsldma.h |   16 ++++++++
>  2 files changed, 116 insertions(+)
> 
> diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
> index c9bf54a..d6da222 100644
> --- a/drivers/dma/fsldma.c
> +++ b/drivers/dma/fsldma.c
> @@ -400,6 +400,14 @@ static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx)
>  
>  	spin_lock_bh(&chan->desc_lock);
>  
> +#ifdef CONFIG_PM
> +	if (unlikely(chan->pm_state != RUNNING)) {
> +		chan_dbg(chan, "cannot submit due to suspend\n");
> +		spin_unlock_bh(&chan->desc_lock);
> +		return -1;
> +	}
> +#endif
> +
>  	/*
>  	 * assign cookies to all of the software descriptors
>  	 * that make up this transaction
> @@ -1311,6 +1319,9 @@ static int fsl_dma_chan_probe(struct fsldma_device *fdev,
>  	INIT_LIST_HEAD(&chan->ld_running);
>  	INIT_LIST_HEAD(&chan->ld_completed);
>  	chan->idle = true;
> +#ifdef CONFIG_PM
> +	chan->pm_state = RUNNING;
> +#endif
>  
>  	chan->common.device = &fdev->common;
>  	dma_cookie_init(&chan->common);
> @@ -1450,6 +1461,92 @@ static int fsldma_of_remove(struct platform_device *op)
>  	return 0;
>  }
>  
> +#ifdef CONFIG_PM
> +static int fsldma_prepare(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct fsldma_device *fdev = platform_get_drvdata(pdev);
> +	struct fsldma_chan *chan;
> +	int i;
> +
> +	for (i = 0; i < FSL_DMA_MAX_CHANS_PER_DEVICE; i++) {
> +		chan = fdev->chan[i];
> +		if (!chan)
> +			continue;
> +
> +		spin_lock_bh(&chan->desc_lock);
> +		chan->pm_state = SUSPENDING;
> +		if (!list_empty(&chan->ld_pending))
> +			fsl_chan_xfer_ld_queue(chan);
> +		spin_unlock_bh(&chan->desc_lock);
> +	}
> +
> +	return 0;
> +}
> +
> +static int fsldma_suspend(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct fsldma_device *fdev = platform_get_drvdata(pdev);
> +	struct fsldma_chan *chan;
> +	int i;
> +
> +	for (i = 0; i < FSL_DMA_MAX_CHANS_PER_DEVICE; i++) {
> +		chan = fdev->chan[i];
> +		if (!chan)
> +			continue;
> +
> +		spin_lock_bh(&chan->desc_lock);
> +		if (!chan->idle)
> +			goto out;
> +		chan->regs_save.mr = DMA_IN(chan, &chan->regs->mr, 32);
> +		chan->pm_state = SUSPENDED;
> +		spin_unlock_bh(&chan->desc_lock);
> +	}
> +	return 0;
> +
> +out:
> +	for (; i >= 0; i--) {
> +		chan = fdev->chan[i];
> +		if (!chan)
> +			continue;
> +		chan->pm_state = RUNNING;
> +		spin_unlock_bh(&chan->desc_lock);
> +	}
> +	return -EBUSY;
> +}
> +
> +static int fsldma_resume(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct fsldma_device *fdev = platform_get_drvdata(pdev);
> +	struct fsldma_chan *chan;
> +	u32 mode;
> +	int i;
> +
> +	for (i = 0; i < FSL_DMA_MAX_CHANS_PER_DEVICE; i++) {
> +		chan = fdev->chan[i];
> +		if (!chan)
> +			continue;
> +
> +		spin_lock_bh(&chan->desc_lock);
> +		mode = chan->regs_save.mr
> +			& ~FSL_DMA_MR_CS & ~FSL_DMA_MR_CC & ~FSL_DMA_MR_CA;
> +		DMA_OUT(chan, &chan->regs->mr, mode, 32);
> +		chan->pm_state = RUNNING;
> +		spin_unlock_bh(&chan->desc_lock);
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops fsldma_pm_ops = {
> +	.prepare	= fsldma_prepare,
> +	.suspend	= fsldma_suspend,
> +	.resume		= fsldma_resume,
> +};
> +#endif
> +
>  static const struct of_device_id fsldma_of_ids[] = {
>  	{ .compatible = "fsl,elo3-dma", },
>  	{ .compatible = "fsl,eloplus-dma", },
> @@ -1462,6 +1559,9 @@ static struct platform_driver fsldma_of_driver = {
>  		.name = "fsl-elo-dma",
>  		.owner = THIS_MODULE,
>  		.of_match_table = fsldma_of_ids,
> +#ifdef CONFIG_PM
> +		.pm = &fsldma_pm_ops,
> +#endif
>  	},
>  	.probe = fsldma_of_probe,
>  	.remove = fsldma_of_remove,
> diff --git a/drivers/dma/fsldma.h b/drivers/dma/fsldma.h
> index ec19517..eecaf9e 100644
> --- a/drivers/dma/fsldma.h
> +++ b/drivers/dma/fsldma.h
> @@ -134,6 +134,18 @@ struct fsldma_device {
>  #define FSL_DMA_CHAN_PAUSE_EXT	0x00001000
>  #define FSL_DMA_CHAN_START_EXT	0x00002000
>  
> +#ifdef CONFIG_PM
> +struct fsldma_chan_regs_save {
> +	u32 mr;
> +};
> +
> +enum fsldma_pm_state {
> +	RUNNING = 0,
> +	SUSPENDING,
> +	SUSPENDED,
> +};
> +#endif
> +
>  struct fsldma_chan {
>  	char name[8];			/* Channel name */
>  	struct fsldma_chan_regs __iomem *regs;
> @@ -161,6 +173,10 @@ struct fsldma_chan {
>  	struct tasklet_struct tasklet;
>  	u32 feature;
>  	bool idle;			/* DMA controller is idle */
> +#ifdef CONFIG_PM
> +	struct fsldma_chan_regs_save regs_save;
> +	enum fsldma_pm_state pm_state;
> +#endif
>  
>  	void (*toggle_ext_pause)(struct fsldma_chan *fsl_chan, int enable);
>  	void (*toggle_ext_start)(struct fsldma_chan *fsl_chan, int enable);


-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

Re: [PATCH v3 8/8] DMA: Freescale: add suspend resume functions for DMA driver

[Hongbo Zhang]

On 04/10/2014 08:05 PM, Andy Shevchenko wrote:
> On Thu, 2014-04-10 at 15:10 +0800, hongbo.zhang@freescale.com wrote:
>> From: Hongbo Zhang <hongbo.zhang@freescale.com>
>>
>> This patch adds suspend resume functions for Freescale DMA driver.
>> .prepare callback is used to stop further descriptors from being added into the
>> pending queue, and also issue pending queues into execution if there is any.
>> .suspend callback makes sure all the pending jobs are cleaned up and all the
>> channels are idle, and save the mode registers.
>> .resume callback re-initializes the channels by restore the mode registers.
> Like we discussed with Vinod [1] the DMA controller drivers should go to
> suspend after users and come back before them.
>
> After you reconsider this point the patch logic might be modified a lot.

Looked through that discussions, I really had thought such problem for a 
while.

For the dma-controller and dma-user, we don't know which .suspend 
callback is executed firstly, so the idea would be: which ever is called 
earlier, the dma-controller driver suspend function should be as  robust 
as possible.

It is better the dma-user .suspend callback is called earlier, some 
clean-ups should be done here such as stop dma request, but we cannot 
make sure every dma-user has a .suspend callback, some dma-users don't 
pay attention to or even don't care the suspend at all for some reason.

So even the suspend_late is used, we cannot assume every dma-user's 
activity is cleaned up neatly, dma-controller driver should be robust to 
handle this gracefully, that was my design target.

In the prepare() function, clean up the pending queue and stop receive 
new coming request, and in the suspend() function I do some register 
saving works. I don't think my code needs to be modified much, a 
possible change according to Vinod's idea would be:
use .suspend instead of my current .prepare
use . suspend_late instead of my current .suspend
e.g. postpone all my functions to be executed later, this method works 
and seems better for client/low-level module drivers.

The reason I didn't use the above functions was that I had read this 
Documentation/power/devices.txt, search the definitions of prepare, 
suspend, suspend_late and suspend_noirq, I think my usage complies with 
that definitions strictly, I can do the modification above if the 
maintainer like and if nobody says I break this law.

> (Moreover, you abuse your own position to use only setters/getters to
> access to the DMAc registers)

My shame, I will update it.
(reason is the setters/getters patch isn't merged into our internal 
tree, but this suspend patch has been done. I am trying to sync our 
internal kernel and the community now)

> [1] http://www.spinics.net/lists/kernel/msg1650974.html
>
>
>> Signed-off-by: Hongbo Zhang <hongbo.zhang@freescale.com>
>> ---
>>   drivers/dma/fsldma.c |  100 ++++++++++++++++++++++++++++++++++++++++++++++++++
>>   drivers/dma/fsldma.h |   16 ++++++++
>>   2 files changed, 116 insertions(+)
>>
>> diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
>> index c9bf54a..d6da222 100644
>> --- a/drivers/dma/fsldma.c
>> +++ b/drivers/dma/fsldma.c
>> @@ -400,6 +400,14 @@ static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx)
>>   
>>   	spin_lock_bh(&chan->desc_lock);
>>   
>> +#ifdef CONFIG_PM
>> +	if (unlikely(chan->pm_state != RUNNING)) {
>> +		chan_dbg(chan, "cannot submit due to suspend\n");
>> +		spin_unlock_bh(&chan->desc_lock);
>> +		return -1;
>> +	}
>> +#endif
>> +
>>   	/*
>>   	 * assign cookies to all of the software descriptors
>>   	 * that make up this transaction
>> @@ -1311,6 +1319,9 @@ static int fsl_dma_chan_probe(struct fsldma_device *fdev,
>>   	INIT_LIST_HEAD(&chan->ld_running);
>>   	INIT_LIST_HEAD(&chan->ld_completed);
>>   	chan->idle = true;
>> +#ifdef CONFIG_PM
>> +	chan->pm_state = RUNNING;
>> +#endif
>>   
>>   	chan->common.device = &fdev->common;
>>   	dma_cookie_init(&chan->common);
>> @@ -1450,6 +1461,92 @@ static int fsldma_of_remove(struct platform_device *op)
>>   	return 0;
>>   }
>>   
>> +#ifdef CONFIG_PM
>> +static int fsldma_prepare(struct device *dev)
>> +{
>> +	struct platform_device *pdev = to_platform_device(dev);
>> +	struct fsldma_device *fdev = platform_get_drvdata(pdev);
>> +	struct fsldma_chan *chan;
>> +	int i;
>> +
>> +	for (i = 0; i < FSL_DMA_MAX_CHANS_PER_DEVICE; i++) {
>> +		chan = fdev->chan[i];
>> +		if (!chan)
>> +			continue;
>> +
>> +		spin_lock_bh(&chan->desc_lock);
>> +		chan->pm_state = SUSPENDING;
>> +		if (!list_empty(&chan->ld_pending))
>> +			fsl_chan_xfer_ld_queue(chan);
>> +		spin_unlock_bh(&chan->desc_lock);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int fsldma_suspend(struct device *dev)
>> +{
>> +	struct platform_device *pdev = to_platform_device(dev);
>> +	struct fsldma_device *fdev = platform_get_drvdata(pdev);
>> +	struct fsldma_chan *chan;
>> +	int i;
>> +
>> +	for (i = 0; i < FSL_DMA_MAX_CHANS_PER_DEVICE; i++) {
>> +		chan = fdev->chan[i];
>> +		if (!chan)
>> +			continue;
>> +
>> +		spin_lock_bh(&chan->desc_lock);
>> +		if (!chan->idle)
>> +			goto out;
>> +		chan->regs_save.mr = DMA_IN(chan, &chan->regs->mr, 32);
>> +		chan->pm_state = SUSPENDED;
>> +		spin_unlock_bh(&chan->desc_lock);
>> +	}
>> +	return 0;
>> +
>> +out:
>> +	for (; i >= 0; i--) {
>> +		chan = fdev->chan[i];
>> +		if (!chan)
>> +			continue;
>> +		chan->pm_state = RUNNING;
>> +		spin_unlock_bh(&chan->desc_lock);
>> +	}
>> +	return -EBUSY;
>> +}
>> +
>> +static int fsldma_resume(struct device *dev)
>> +{
>> +	struct platform_device *pdev = to_platform_device(dev);
>> +	struct fsldma_device *fdev = platform_get_drvdata(pdev);
>> +	struct fsldma_chan *chan;
>> +	u32 mode;
>> +	int i;
>> +
>> +	for (i = 0; i < FSL_DMA_MAX_CHANS_PER_DEVICE; i++) {
>> +		chan = fdev->chan[i];
>> +		if (!chan)
>> +			continue;
>> +
>> +		spin_lock_bh(&chan->desc_lock);
>> +		mode = chan->regs_save.mr
>> +			& ~FSL_DMA_MR_CS & ~FSL_DMA_MR_CC & ~FSL_DMA_MR_CA;
>> +		DMA_OUT(chan, &chan->regs->mr, mode, 32);
>> +		chan->pm_state = RUNNING;
>> +		spin_unlock_bh(&chan->desc_lock);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct dev_pm_ops fsldma_pm_ops = {
>> +	.prepare	= fsldma_prepare,
>> +	.suspend	= fsldma_suspend,
>> +	.resume		= fsldma_resume,
>> +};
>> +#endif
>> +
>>   static const struct of_device_id fsldma_of_ids[] = {
>>   	{ .compatible = "fsl,elo3-dma", },
>>   	{ .compatible = "fsl,eloplus-dma", },
>> @@ -1462,6 +1559,9 @@ static struct platform_driver fsldma_of_driver = {
>>   		.name = "fsl-elo-dma",
>>   		.owner = THIS_MODULE,
>>   		.of_match_table = fsldma_of_ids,
>> +#ifdef CONFIG_PM
>> +		.pm = &fsldma_pm_ops,
>> +#endif
>>   	},
>>   	.probe = fsldma_of_probe,
>>   	.remove = fsldma_of_remove,
>> diff --git a/drivers/dma/fsldma.h b/drivers/dma/fsldma.h
>> index ec19517..eecaf9e 100644
>> --- a/drivers/dma/fsldma.h
>> +++ b/drivers/dma/fsldma.h
>> @@ -134,6 +134,18 @@ struct fsldma_device {
>>   #define FSL_DMA_CHAN_PAUSE_EXT	0x00001000
>>   #define FSL_DMA_CHAN_START_EXT	0x00002000
>>   
>> +#ifdef CONFIG_PM
>> +struct fsldma_chan_regs_save {
>> +	u32 mr;
>> +};
>> +
>> +enum fsldma_pm_state {
>> +	RUNNING = 0,
>> +	SUSPENDING,
>> +	SUSPENDED,
>> +};
>> +#endif
>> +
>>   struct fsldma_chan {
>>   	char name[8];			/* Channel name */
>>   	struct fsldma_chan_regs __iomem *regs;
>> @@ -161,6 +173,10 @@ struct fsldma_chan {
>>   	struct tasklet_struct tasklet;
>>   	u32 feature;
>>   	bool idle;			/* DMA controller is idle */
>> +#ifdef CONFIG_PM
>> +	struct fsldma_chan_regs_save regs_save;
>> +	enum fsldma_pm_state pm_state;
>> +#endif
>>   
>>   	void (*toggle_ext_pause)(struct fsldma_chan *fsl_chan, int enable);
>>   	void (*toggle_ext_start)(struct fsldma_chan *fsl_chan, int enable);
>