[PATCH v3] dmaengine: dw-edma: Enable HDMA 64R/W Channels

[PATCH v3] dmaengine: dw-edma: Enable HDMA 64R/W Channels

[Devendra K Verma]

As per 'Designware Cores PCI Express Controller Databook',
Section 7.1 - Overview, HDMA supports 64 Read and 64 Write
channels. Current controller driver supports up to 8 read and
write channels only. In order to utilize all the channels the
controller driver need to have the channel related structs
and variables as per the number of channels supported by IP.
Following changes are made to enable 64 Read / 64 Write
channel support:

 o Defined HDMA specific macros to reflect the channel count.
 o The count of ll_regions and dt_regions in dw_edma_chip and
   dw_edma_pcie_data shall be in accordance to number of read
   and write channels.
 o In dw_edma_probe() configure the channels as per the channels
   of the IP used.
 o Changed mask types to u64 for higher channel counts.

Signed-off-by: Devendra K Verma <devendra.verma@amd.com>
---
Changes in v2:
  o Fixed the pre-existing bug related to GET_CH_32
    interchanging the channel direction and id.
    This bug was not caused by any version of this patch.
  o Fixed the issue when using for_each_set_bit() for mask
    of u64 type.

Changes in v1:
  o On review recommendation of sashiko bot, in the function
    dw_hdma_v0_core_off(), the loop iterates over registers
    as per the number of channels enabled and not on total
    number of channels supported.
  o Changed mask types to u64 for higher channel counts.
---
 drivers/dma/dw-edma/dw-edma-core.c    | 19 ++++++++++-----
 drivers/dma/dw-edma/dw-edma-core.h    |  4 +--
 drivers/dma/dw-edma/dw-edma-pcie.c    |  8 +++---
 drivers/dma/dw-edma/dw-hdma-v0-core.c | 35 ++++++++++++++++++++-------
 drivers/dma/dw-edma/dw-hdma-v0-regs.h |  2 +-
 include/linux/dma/edma.h              | 10 +++++---
 6 files changed, 52 insertions(+), 26 deletions(-)

diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
index c2feb3adc79f..adf1b3939f96 100644
--- a/drivers/dma/dw-edma/dw-edma-core.c
+++ b/drivers/dma/dw-edma/dw-edma-core.c
@@ -925,9 +925,9 @@ static int dw_edma_channel_setup(struct dw_edma *dw, u32 wr_alloc, u32 rd_alloc)
 		irq = &dw->irq[pos];
 
 		if (chan->dir == EDMA_DIR_WRITE)
-			irq->wr_mask |= BIT(chan->id);
+			irq->wr_mask |= BIT_ULL(chan->id);
 		else
-			irq->rd_mask |= BIT(chan->id);
+			irq->rd_mask |= BIT_ULL(chan->id);
 
 		irq->dw = dw;
 		memcpy(&chan->msi, &irq->msi, sizeof(chan->msi));
@@ -1079,6 +1079,8 @@ int dw_edma_probe(struct dw_edma_chip *chip)
 	struct dw_edma *dw;
 	u32 wr_alloc = 0;
 	u32 rd_alloc = 0;
+	u16 max_wr_cnt;
+	u16 max_rd_cnt;
 	int i, err;
 
 	if (!chip)
@@ -1094,20 +1096,25 @@ int dw_edma_probe(struct dw_edma_chip *chip)
 
 	dw->chip = chip;
 
-	if (dw->chip->mf == EDMA_MF_HDMA_NATIVE)
+	if (dw->chip->mf == EDMA_MF_HDMA_NATIVE) {
 		dw_hdma_v0_core_register(dw);
-	else
+		max_wr_cnt = HDMA_MAX_WR_CH;
+		max_rd_cnt = HDMA_MAX_RD_CH;
+	} else {
 		dw_edma_v0_core_register(dw);
+		max_wr_cnt = EDMA_MAX_WR_CH;
+		max_rd_cnt = EDMA_MAX_RD_CH;
+	}
 
 	raw_spin_lock_init(&dw->lock);
 
 	dw->wr_ch_cnt = min_t(u16, chip->ll_wr_cnt,
 			      dw_edma_core_ch_count(dw, EDMA_DIR_WRITE));
-	dw->wr_ch_cnt = min_t(u16, dw->wr_ch_cnt, EDMA_MAX_WR_CH);
+	dw->wr_ch_cnt = min_t(u16, dw->wr_ch_cnt, max_wr_cnt);
 
 	dw->rd_ch_cnt = min_t(u16, chip->ll_rd_cnt,
 			      dw_edma_core_ch_count(dw, EDMA_DIR_READ));
-	dw->rd_ch_cnt = min_t(u16, dw->rd_ch_cnt, EDMA_MAX_RD_CH);
+	dw->rd_ch_cnt = min_t(u16, dw->rd_ch_cnt, max_rd_cnt);
 
 	if (!dw->wr_ch_cnt && !dw->rd_ch_cnt)
 		return -EINVAL;
diff --git a/drivers/dma/dw-edma/dw-edma-core.h b/drivers/dma/dw-edma/dw-edma-core.h
index 902574b1ba86..d12fefbf3952 100644
--- a/drivers/dma/dw-edma/dw-edma-core.h
+++ b/drivers/dma/dw-edma/dw-edma-core.h
@@ -91,8 +91,8 @@ struct dw_edma_chan {
 
 struct dw_edma_irq {
 	struct msi_msg                  msi;
-	u32				wr_mask;
-	u32				rd_mask;
+	u64				wr_mask;
+	u64				rd_mask;
 	struct dw_edma			*dw;
 };
 
diff --git a/drivers/dma/dw-edma/dw-edma-pcie.c b/drivers/dma/dw-edma/dw-edma-pcie.c
index 0b30ce138503..79f653da8e0f 100644
--- a/drivers/dma/dw-edma/dw-edma-pcie.c
+++ b/drivers/dma/dw-edma/dw-edma-pcie.c
@@ -61,11 +61,11 @@ struct dw_edma_pcie_data {
 	/* eDMA registers location */
 	struct dw_edma_block		rg;
 	/* eDMA memory linked list location */
-	struct dw_edma_block		ll_wr[EDMA_MAX_WR_CH];
-	struct dw_edma_block		ll_rd[EDMA_MAX_RD_CH];
+	struct dw_edma_block		ll_wr[HDMA_MAX_WR_CH];
+	struct dw_edma_block		ll_rd[HDMA_MAX_RD_CH];
 	/* eDMA memory data location */
-	struct dw_edma_block		dt_wr[EDMA_MAX_WR_CH];
-	struct dw_edma_block		dt_rd[EDMA_MAX_RD_CH];
+	struct dw_edma_block		dt_wr[HDMA_MAX_WR_CH];
+	struct dw_edma_block		dt_rd[HDMA_MAX_RD_CH];
 	/* Other */
 	enum dw_edma_map_format		mf;
 	u8				irqs;
diff --git a/drivers/dma/dw-edma/dw-hdma-v0-core.c b/drivers/dma/dw-edma/dw-hdma-v0-core.c
index 632abb8b481c..d4cfb2d456ab 100644
--- a/drivers/dma/dw-edma/dw-hdma-v0-core.c
+++ b/drivers/dma/dw-edma/dw-hdma-v0-core.c
@@ -53,13 +53,24 @@ __dw_ch_regs(struct dw_edma *dw, enum dw_edma_dir dir, u16 ch)
 static void dw_hdma_v0_core_off(struct dw_edma *dw)
 {
 	int id;
+	enum dw_edma_dir dir;
+
+	dir = EDMA_DIR_WRITE;
+	for (id = 0; id < dw->wr_ch_cnt; id++) {
+		SET_CH_32(dw, dir, id, int_setup,
+			  HDMA_V0_STOP_INT_MASK | HDMA_V0_ABORT_INT_MASK);
+		SET_CH_32(dw, dir, id, int_clear,
+			  HDMA_V0_STOP_INT_MASK | HDMA_V0_ABORT_INT_MASK);
+		SET_CH_32(dw, dir, id, ch_en, 0);
+	}
 
-	for (id = 0; id < HDMA_V0_MAX_NR_CH; id++) {
-		SET_BOTH_CH_32(dw, id, int_setup,
-			       HDMA_V0_STOP_INT_MASK | HDMA_V0_ABORT_INT_MASK);
-		SET_BOTH_CH_32(dw, id, int_clear,
-			       HDMA_V0_STOP_INT_MASK | HDMA_V0_ABORT_INT_MASK);
-		SET_BOTH_CH_32(dw, id, ch_en, 0);
+	dir = EDMA_DIR_READ;
+	for (id = 0; id < dw->rd_ch_cnt; id++) {
+		SET_CH_32(dw, dir, id, int_setup,
+			  HDMA_V0_STOP_INT_MASK | HDMA_V0_ABORT_INT_MASK);
+		SET_CH_32(dw, dir, id, int_clear,
+			  HDMA_V0_STOP_INT_MASK | HDMA_V0_ABORT_INT_MASK);
+		SET_CH_32(dw, dir, id, ch_en, 0);
 	}
 }
 
@@ -79,7 +90,7 @@ static enum dma_status dw_hdma_v0_core_ch_status(struct dw_edma_chan *chan)
 	u32 tmp;
 
 	tmp = FIELD_GET(HDMA_V0_CH_STATUS_MASK,
-			GET_CH_32(dw, chan->id, chan->dir, ch_stat));
+			GET_CH_32(dw, chan->dir, chan->id, ch_stat));
 
 	if (tmp == 1)
 		return DMA_IN_PROGRESS;
@@ -118,7 +129,8 @@ dw_hdma_v0_core_handle_int(struct dw_edma_irq *dw_irq, enum dw_edma_dir dir,
 	unsigned long total, pos, val;
 	irqreturn_t ret = IRQ_NONE;
 	struct dw_edma_chan *chan;
-	unsigned long off, mask;
+	unsigned long off;
+	u64 mask;
 
 	if (dir == EDMA_DIR_WRITE) {
 		total = dw->wr_ch_cnt;
@@ -130,7 +142,11 @@ dw_hdma_v0_core_handle_int(struct dw_edma_irq *dw_irq, enum dw_edma_dir dir,
 		mask = dw_irq->rd_mask;
 	}
 
-	for_each_set_bit(pos, &mask, total) {
+	while (mask) {
+		pos = __ffs64(mask);
+		if (pos >= total)
+			break;
+
 		chan = &dw->chan[pos + off];
 
 		val = dw_hdma_v0_core_status_int(chan);
@@ -147,6 +163,7 @@ dw_hdma_v0_core_handle_int(struct dw_edma_irq *dw_irq, enum dw_edma_dir dir,
 
 			ret = IRQ_HANDLED;
 		}
+		mask &= mask - 1;
 	}
 
 	return ret;
diff --git a/drivers/dma/dw-edma/dw-hdma-v0-regs.h b/drivers/dma/dw-edma/dw-hdma-v0-regs.h
index 7759ba9b4850..48e40efceb2e 100644
--- a/drivers/dma/dw-edma/dw-hdma-v0-regs.h
+++ b/drivers/dma/dw-edma/dw-hdma-v0-regs.h
@@ -11,7 +11,7 @@
 
 #include <linux/dmaengine.h>
 
-#define HDMA_V0_MAX_NR_CH			8
+#define HDMA_V0_MAX_NR_CH			64
 #define HDMA_V0_CH_EN				BIT(0)
 #define HDMA_V0_LOCAL_ABORT_INT_EN		BIT(6)
 #define HDMA_V0_REMOTE_ABORT_INT_EN		BIT(5)
diff --git a/include/linux/dma/edma.h b/include/linux/dma/edma.h
index 1fafd5b0e315..da7a5cc93ad4 100644
--- a/include/linux/dma/edma.h
+++ b/include/linux/dma/edma.h
@@ -14,6 +14,8 @@
 
 #define EDMA_MAX_WR_CH                                  8
 #define EDMA_MAX_RD_CH                                  8
+#define HDMA_MAX_WR_CH                                  64
+#define HDMA_MAX_RD_CH                                  64
 
 struct dw_edma;
 
@@ -89,12 +91,12 @@ struct dw_edma_chip {
 	u16			ll_wr_cnt;
 	u16			ll_rd_cnt;
 	/* link list address */
-	struct dw_edma_region	ll_region_wr[EDMA_MAX_WR_CH];
-	struct dw_edma_region	ll_region_rd[EDMA_MAX_RD_CH];
+	struct dw_edma_region	ll_region_wr[HDMA_MAX_WR_CH];
+	struct dw_edma_region	ll_region_rd[HDMA_MAX_RD_CH];
 
 	/* data region */
-	struct dw_edma_region	dt_region_wr[EDMA_MAX_WR_CH];
-	struct dw_edma_region	dt_region_rd[EDMA_MAX_RD_CH];
+	struct dw_edma_region	dt_region_wr[HDMA_MAX_WR_CH];
+	struct dw_edma_region	dt_region_rd[HDMA_MAX_RD_CH];
 
 	/* interrupt emulation */
 	int			db_irq;
-- 
2.43.0

Re: [PATCH v3] dmaengine: dw-edma: Enable HDMA 64R/W Channels

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 3 potential issue(s) to consider:

New issues:
- [High] The 64-channel HDMA feature is unreachable because platform glue drivers still enforce legacy 8-channel hardcoded limits.

Pre-existing issues:
- [High] The eDMA subsystem is deregistered AFTER the hardware core is disabled and IRQs are freed, violating tear-down symmetry.
- [High] The virt-dma descriptors are never freed when a channel is released, leading to a permanent memory leak.
--

commit 20ba395bede7014c18b81804a5f6a941f3a95ebd
Author: Devendra K Verma <devendra.verma@amd.com>

dmaengine: dw-edma: Enable HDMA 64R/W Channels

As per 'Designware Cores PCI Express Controller Databook',
Section 7.1 - Overview, HDMA supports 64 Read and 64 Write
channels. Current controller driver supports up to 8 read and
write channels only. In order to utilize all the channels the
controller driver need to have the channel related structs
and variables as per the number of channels supported by IP.

> diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
> index c2feb3adc79fa..adf1b3939f96c 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-core.c

[ ... ]

> @@ -1079,6 +1079,8 @@ int dw_edma_probe(struct dw_edma_chip *chip)
>  	struct dw_edma *dw;
>  	u32 wr_alloc = 0;
>  	u32 rd_alloc = 0;
> +	u16 max_wr_cnt;
> +	u16 max_rd_cnt;
>  	int i, err;
>  
>  	if (!chip)
> @@ -1094,20 +1096,25 @@ int dw_edma_probe(struct dw_edma_chip *chip)
>  
>  	dw->chip = chip;
>  
> -	if (dw->chip->mf == EDMA_MF_HDMA_NATIVE)
> +	if (dw->chip->mf == EDMA_MF_HDMA_NATIVE) {
>  		dw_hdma_v0_core_register(dw);
> -	else
> +		max_wr_cnt = HDMA_MAX_WR_CH;
> +		max_rd_cnt = HDMA_MAX_RD_CH;
> +	} else {
>  		dw_edma_v0_core_register(dw);
> +		max_wr_cnt = EDMA_MAX_WR_CH;
> +		max_rd_cnt = EDMA_MAX_RD_CH;
> +	}
>  
>  	raw_spin_lock_init(&dw->lock);
>  
>  	dw->wr_ch_cnt = min_t(u16, chip->ll_wr_cnt,
>  			      dw_edma_core_ch_count(dw, EDMA_DIR_WRITE));
> -	dw->wr_ch_cnt = min_t(u16, dw->wr_ch_cnt, EDMA_MAX_WR_CH);
> +	dw->wr_ch_cnt = min_t(u16, dw->wr_ch_cnt, max_wr_cnt);
>  
>  	dw->rd_ch_cnt = min_t(u16, chip->ll_rd_cnt,
>  			      dw_edma_core_ch_count(dw, EDMA_DIR_READ));
> -	dw->rd_ch_cnt = min_t(u16, dw->rd_ch_cnt, EDMA_MAX_RD_CH);
> +	dw->rd_ch_cnt = min_t(u16, dw->rd_ch_cnt, max_rd_cnt);
>  
>  	if (!dw->wr_ch_cnt && !dw->rd_ch_cnt)
>  		return -EINVAL;

[Severity: High]
This patch expands the eDMA core structures to support up to 64 HDMA channels.
However, does it miss updating the PCIe instantiation wrappers, rendering the
feature unusable?

In drivers/pci/controller/dwc/pcie-designware.c, dw_pcie_edma_find_channels()
performs a sanity check that explicitly rejects any configuration exceeding
EDMA_MAX_WR_CH (8), returning -EINVAL:

	if (!pci->edma.ll_wr_cnt || pci->edma.ll_wr_cnt > EDMA_MAX_WR_CH ||
	    !pci->edma.ll_rd_cnt || pci->edma.ll_rd_cnt > EDMA_MAX_RD_CH)
		return -EINVAL;

Similarly, dw_pcie_edma_irq_vector() limits IRQ indices to 16
(EDMA_MAX_WR_CH + EDMA_MAX_RD_CH).

Furthermore, in drivers/dma/dw-edma/dw-edma-pcie.c, the functions
dw_edma_pcie_get_synopsys_dma_data() and dw_edma_pcie_get_xilinx_dma_data()
use min_t to bound the hardware-reported channel count against
pdata->wr_ch_cnt (which is statically initialized to 2 or 8):

	pdata->wr_ch_cnt = min_t(u16, pdata->wr_ch_cnt,
				 FIELD_GET(DW_PCIE_SYNOPSYS_VSEC_DMA_WR_CH, val));

Will any attempt to configure an HDMA device with >8 channels be silently
truncated to 8 or fail to probe completely?


[Severity: High]
This is a pre-existing issue, but looking at dw_edma_remove(), the eDMA
subsystem is deregistered after the hardware core is disabled and IRQs are
freed. Does this violate tear-down symmetry?

In dw_edma_remove(), the driver first calls dw_edma_core_off(dw) to disable
the hardware, and then frees all IRQs using free_irq(). Only after that does
it call dma_async_device_unregister(&dw->dma) and kill the virt-dma tasklets:

	/* Disable eDMA */
	dw_edma_core_off(dw);

	/* Free irqs */
	for (i = (dw->nr_irqs - 1); i >= 0; i--)
		free_irq(chip->ops->irq_vector(dev, i), &dw->irq[i]);
	dw_edma_emul_irq_free(dw);

	/* Deregister eDMA device */
	dma_async_device_unregister(&dw->dma);

If a client still holds a reference and has an active DMA transfer or submits
a new one while the device is being removed, the transfer cannot complete
because the hardware is disabled and interrupts are freed. Can this lead to a
hung task or a DMA timeout?


[Severity: High]
This is a pre-existing issue, but does the driver leak virt-dma descriptors
permanently when a channel is released?

The virt-dma framework requires drivers to call vchan_free_chan_resources()
from their .device_free_chan_resources callback to free all pending, submitted,
and allocated descriptors. The dw_edma_free_chan_resources() function waits for
the channel to stop but fails to call vchan_free_chan_resources(&chan->vc)
or manually free the descriptors:

static void dw_edma_free_chan_resources(struct dma_chan *dchan)
{
	unsigned long timeout = jiffies + msecs_to_jiffies(5000);
	int ret;

	while (time_before(jiffies, timeout)) {
		ret = dw_edma_device_terminate_all(dchan);
		... 
	}
}

As a result, every time a client allocates descriptors and then releases the
channel, are all those descriptors permanently leaked?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260603144147.3249691-1-devendra.verma@amd.com?part=1

RE: [PATCH v3] dmaengine: dw-edma: Enable HDMA 64R/W Channels

[Verma, Devendra]

AMD General

> -----Original Message-----
> From: sashiko-bot@kernel.org <sashiko-bot@kernel.org>
> Sent: Wednesday, June 3, 2026 20:28
> To: Verma, Devendra <Devendra.Verma@amd.com>
> Cc: vkoul@kernel.org; Frank.Li@kernel.org; dmaengine@vger.kernel.org
> Subject: Re: [PATCH v3] dmaengine: dw-edma: Enable HDMA 64R/W
> Channels
>
> Thank you for your contribution! Sashiko AI review found 3 potential issue(s)
> to consider:
>
> New issues:
> - [High] The 64-channel HDMA feature is unreachable because platform glue
> drivers still enforce legacy 8-channel hardcoded limits.
>

This can be taken up in a separate patch but there is no glue driver at the
moment that uses 64 channels.

> Pre-existing issues:
> - [High] The eDMA subsystem is deregistered AFTER the hardware core is
> disabled and IRQs are freed, violating tear-down symmetry.
> - [High] The virt-dma descriptors are never freed when a channel is released,
> leading to a permanent memory leak.

These issues also can be taken up in a separate patch series.

> --
>
> commit 20ba395bede7014c18b81804a5f6a941f3a95ebd
> Author: Devendra K Verma <devendra.verma@amd.com>
>
> dmaengine: dw-edma: Enable HDMA 64R/W Channels
>
> As per 'Designware Cores PCI Express Controller Databook', Section 7.1 -
> Overview, HDMA supports 64 Read and 64 Write channels. Current controller
> driver supports up to 8 read and write channels only. In order to utilize all the
> channels the controller driver need to have the channel related structs and
> variables as per the number of channels supported by IP.
>
> > diff --git a/drivers/dma/dw-edma/dw-edma-core.c
> > b/drivers/dma/dw-edma/dw-edma-core.c
> > index c2feb3adc79fa..adf1b3939f96c 100644
> > --- a/drivers/dma/dw-edma/dw-edma-core.c
> > +++ b/drivers/dma/dw-edma/dw-edma-core.c
>
> [ ... ]
>
> > @@ -1079,6 +1079,8 @@ int dw_edma_probe(struct dw_edma_chip *chip)
> >     struct dw_edma *dw;
> >     u32 wr_alloc = 0;
> >     u32 rd_alloc = 0;
> > +   u16 max_wr_cnt;
> > +   u16 max_rd_cnt;
> >     int i, err;
> >
> >     if (!chip)
> > @@ -1094,20 +1096,25 @@ int dw_edma_probe(struct dw_edma_chip
> *chip)
> >
> >     dw->chip = chip;
> >
> > -   if (dw->chip->mf == EDMA_MF_HDMA_NATIVE)
> > +   if (dw->chip->mf == EDMA_MF_HDMA_NATIVE) {
> >             dw_hdma_v0_core_register(dw);
> > -   else
> > +           max_wr_cnt = HDMA_MAX_WR_CH;
> > +           max_rd_cnt = HDMA_MAX_RD_CH;
> > +   } else {
> >             dw_edma_v0_core_register(dw);
> > +           max_wr_cnt = EDMA_MAX_WR_CH;
> > +           max_rd_cnt = EDMA_MAX_RD_CH;
> > +   }
> >
> >     raw_spin_lock_init(&dw->lock);
> >
> >     dw->wr_ch_cnt = min_t(u16, chip->ll_wr_cnt,
> >                           dw_edma_core_ch_count(dw,
> EDMA_DIR_WRITE));
> > -   dw->wr_ch_cnt = min_t(u16, dw->wr_ch_cnt, EDMA_MAX_WR_CH);
> > +   dw->wr_ch_cnt = min_t(u16, dw->wr_ch_cnt, max_wr_cnt);
> >
> >     dw->rd_ch_cnt = min_t(u16, chip->ll_rd_cnt,
> >                           dw_edma_core_ch_count(dw, EDMA_DIR_READ));
> > -   dw->rd_ch_cnt = min_t(u16, dw->rd_ch_cnt, EDMA_MAX_RD_CH);
> > +   dw->rd_ch_cnt = min_t(u16, dw->rd_ch_cnt, max_rd_cnt);
> >
> >     if (!dw->wr_ch_cnt && !dw->rd_ch_cnt)
> >             return -EINVAL;
>
> [Severity: High]
> This patch expands the eDMA core structures to support up to 64 HDMA
> channels.
> However, does it miss updating the PCIe instantiation wrappers, rendering the
> feature unusable?
>
> In drivers/pci/controller/dwc/pcie-designware.c,
> dw_pcie_edma_find_channels() performs a sanity check that explicitly rejects
> any configuration exceeding EDMA_MAX_WR_CH (8), returning -EINVAL:
>
>       if (!pci->edma.ll_wr_cnt || pci->edma.ll_wr_cnt >
> EDMA_MAX_WR_CH ||
>           !pci->edma.ll_rd_cnt || pci->edma.ll_rd_cnt > EDMA_MAX_RD_CH)
>               return -EINVAL;
>
> Similarly, dw_pcie_edma_irq_vector() limits IRQ indices to 16
> (EDMA_MAX_WR_CH + EDMA_MAX_RD_CH).
>
> Furthermore, in drivers/dma/dw-edma/dw-edma-pcie.c, the functions
> dw_edma_pcie_get_synopsys_dma_data() and
> dw_edma_pcie_get_xilinx_dma_data()
> use min_t to bound the hardware-reported channel count against
> pdata->wr_ch_cnt (which is statically initialized to 2 or 8):
>
>       pdata->wr_ch_cnt = min_t(u16, pdata->wr_ch_cnt,
>
> FIELD_GET(DW_PCIE_SYNOPSYS_VSEC_DMA_WR_CH, val));
>
> Will any attempt to configure an HDMA device with >8 channels be silently
> truncated to 8 or fail to probe completely?
>
>
> [Severity: High]
> This is a pre-existing issue, but looking at dw_edma_remove(), the eDMA
> subsystem is deregistered after the hardware core is disabled and IRQs are
> freed. Does this violate tear-down symmetry?
>
> In dw_edma_remove(), the driver first calls dw_edma_core_off(dw) to
> disable the hardware, and then frees all IRQs using free_irq(). Only after that
> does it call dma_async_device_unregister(&dw->dma) and kill the virt-dma
> tasklets:
>
>       /* Disable eDMA */
>       dw_edma_core_off(dw);
>
>       /* Free irqs */
>       for (i = (dw->nr_irqs - 1); i >= 0; i--)
>               free_irq(chip->ops->irq_vector(dev, i), &dw->irq[i]);
>       dw_edma_emul_irq_free(dw);
>
>       /* Deregister eDMA device */
>       dma_async_device_unregister(&dw->dma);
>
> If a client still holds a reference and has an active DMA transfer or submits a
> new one while the device is being removed, the transfer cannot complete
> because the hardware is disabled and interrupts are freed. Can this lead to a
> hung task or a DMA timeout?
>
>
> [Severity: High]
> This is a pre-existing issue, but does the driver leak virt-dma descriptors
> permanently when a channel is released?
>
> The virt-dma framework requires drivers to call vchan_free_chan_resources()
> from their .device_free_chan_resources callback to free all pending,
> submitted, and allocated descriptors. The dw_edma_free_chan_resources()
> function waits for the channel to stop but fails to call
> vchan_free_chan_resources(&chan->vc)
> or manually free the descriptors:
>
> static void dw_edma_free_chan_resources(struct dma_chan *dchan) {
>       unsigned long timeout = jiffies + msecs_to_jiffies(5000);
>       int ret;
>
>       while (time_before(jiffies, timeout)) {
>               ret = dw_edma_device_terminate_all(dchan);
>               ...
>       }
> }
>
> As a result, every time a client allocates descriptors and then releases the
> channel, are all those descriptors permanently leaked?
>
> --
> Sashiko AI review · https://sashiko.dev/#/patchset/20260603144147.3249691-
> 1-devendra.verma@amd.com?part=1

Re: [PATCH v3] dmaengine: dw-edma: Enable HDMA 64R/W Channels

[Frank Li]

On Wed, Jun 03, 2026 at 08:11:47PM +0530, Devendra K Verma wrote:
> As per 'Designware Cores PCI Express Controller Databook',
> Section 7.1 - Overview, HDMA supports 64 Read and 64 Write
> channels. Current controller driver supports up to 8 read and
> write channels only. In order to utilize all the channels the
> controller driver need to have the channel related structs
> and variables as per the number of channels supported by IP.
> Following changes are made to enable 64 Read / 64 Write
> channel support:
>
>  o Defined HDMA specific macros to reflect the channel count.
>  o The count of ll_regions and dt_regions in dw_edma_chip and
>    dw_edma_pcie_data shall be in accordance to number of read
>    and write channels.
>  o In dw_edma_probe() configure the channels as per the channels
>    of the IP used.
>  o Changed mask types to u64 for higher channel counts.
>
> Signed-off-by: Devendra K Verma <devendra.verma@amd.com>
> ---
> Changes in v2:
>   o Fixed the pre-existing bug related to GET_CH_32
>     interchanging the channel direction and id.
>     This bug was not caused by any version of this patch.
>   o Fixed the issue when using for_each_set_bit() for mask
>     of u64 type.
>
> Changes in v1:
>   o On review recommendation of sashiko bot, in the function
>     dw_hdma_v0_core_off(), the loop iterates over registers
>     as per the number of channels enabled and not on total
>     number of channels supported.
>   o Changed mask types to u64 for higher channel counts.
> ---
...
> +++ b/drivers/dma/dw-edma/dw-hdma-v0-core.c
> @@ -53,13 +53,24 @@ __dw_ch_regs(struct dw_edma *dw, enum dw_edma_dir dir, u16 ch)
>  static void dw_hdma_v0_core_off(struct dw_edma *dw)
>  {
>  	int id;
> +	enum dw_edma_dir dir;
> +
> +	dir = EDMA_DIR_WRITE;
> +	for (id = 0; id < dw->wr_ch_cnt; id++) {
> +		SET_CH_32(dw, dir, id, int_setup,
> +			  HDMA_V0_STOP_INT_MASK | HDMA_V0_ABORT_INT_MASK);
> +		SET_CH_32(dw, dir, id, int_clear,
> +			  HDMA_V0_STOP_INT_MASK | HDMA_V0_ABORT_INT_MASK);
> +		SET_CH_32(dw, dir, id, ch_en, 0);
> +	}
>
> -	for (id = 0; id < HDMA_V0_MAX_NR_CH; id++) {
> -		SET_BOTH_CH_32(dw, id, int_setup,
> -			       HDMA_V0_STOP_INT_MASK | HDMA_V0_ABORT_INT_MASK);
> -		SET_BOTH_CH_32(dw, id, int_clear,
> -			       HDMA_V0_STOP_INT_MASK | HDMA_V0_ABORT_INT_MASK);
> -		SET_BOTH_CH_32(dw, id, ch_en, 0);
> +	dir = EDMA_DIR_READ;
> +	for (id = 0; id < dw->rd_ch_cnt; id++) {
> +		SET_CH_32(dw, dir, id, int_setup,
> +			  HDMA_V0_STOP_INT_MASK | HDMA_V0_ABORT_INT_MASK);
> +		SET_CH_32(dw, dir, id, int_clear,
> +			  HDMA_V0_STOP_INT_MASK | HDMA_V0_ABORT_INT_MASK);
> +		SET_CH_32(dw, dir, id, ch_en, 0);

why SET_BOTH_CH_32 not work for 64 channel?

>  	}
>  }
>
> @@ -79,7 +90,7 @@ static enum dma_status dw_hdma_v0_core_ch_status(struct dw_edma_chan *chan)
>  	u32 tmp;
>
>  	tmp = FIELD_GET(HDMA_V0_CH_STATUS_MASK,
> -			GET_CH_32(dw, chan->id, chan->dir, ch_stat));
> +			GET_CH_32(dw, chan->dir, chan->id, ch_stat));

why need swtich id and dir here ?

Frank
>
>  	if (tmp == 1)
>  		return DMA_IN_PROGRESS;
> @@ -118,7 +129,8 @@ dw_hdma_v0_core_handle_int(struct dw_edma_irq *dw_irq, enum dw_edma_dir dir,
>  	unsigned long total, pos, val;
>  	irqreturn_t ret = IRQ_NONE;
>  	struct dw_edma_chan *chan;
> -	unsigned long off, mask;
> +	unsigned long off;
> +	u64 mask;
>
>  	if (dir == EDMA_DIR_WRITE) {
>  		total = dw->wr_ch_cnt;
> @@ -130,7 +142,11 @@ dw_hdma_v0_core_handle_int(struct dw_edma_irq *dw_irq, enum dw_edma_dir dir,
>  		mask = dw_irq->rd_mask;
>  	}
>
> -	for_each_set_bit(pos, &mask, total) {
> +	while (mask) {
> +		pos = __ffs64(mask);
> +		if (pos >= total)
> +			break;
> +
>  		chan = &dw->chan[pos + off];
>
>  		val = dw_hdma_v0_core_status_int(chan);
> @@ -147,6 +163,7 @@ dw_hdma_v0_core_handle_int(struct dw_edma_irq *dw_irq, enum dw_edma_dir dir,
>
>  			ret = IRQ_HANDLED;
>  		}
> +		mask &= mask - 1;
>  	}
>
>  	return ret;
> diff --git a/drivers/dma/dw-edma/dw-hdma-v0-regs.h b/drivers/dma/dw-edma/dw-hdma-v0-regs.h
> index 7759ba9b4850..48e40efceb2e 100644
> --- a/drivers/dma/dw-edma/dw-hdma-v0-regs.h
> +++ b/drivers/dma/dw-edma/dw-hdma-v0-regs.h
> @@ -11,7 +11,7 @@
>
>  #include <linux/dmaengine.h>
>
> -#define HDMA_V0_MAX_NR_CH			8
> +#define HDMA_V0_MAX_NR_CH			64
>  #define HDMA_V0_CH_EN				BIT(0)
>  #define HDMA_V0_LOCAL_ABORT_INT_EN		BIT(6)
>  #define HDMA_V0_REMOTE_ABORT_INT_EN		BIT(5)
> diff --git a/include/linux/dma/edma.h b/include/linux/dma/edma.h
> index 1fafd5b0e315..da7a5cc93ad4 100644
> --- a/include/linux/dma/edma.h
> +++ b/include/linux/dma/edma.h
> @@ -14,6 +14,8 @@
>
>  #define EDMA_MAX_WR_CH                                  8
>  #define EDMA_MAX_RD_CH                                  8
> +#define HDMA_MAX_WR_CH                                  64
> +#define HDMA_MAX_RD_CH                                  64
>
>  struct dw_edma;
>
> @@ -89,12 +91,12 @@ struct dw_edma_chip {
>  	u16			ll_wr_cnt;
>  	u16			ll_rd_cnt;
>  	/* link list address */
> -	struct dw_edma_region	ll_region_wr[EDMA_MAX_WR_CH];
> -	struct dw_edma_region	ll_region_rd[EDMA_MAX_RD_CH];
> +	struct dw_edma_region	ll_region_wr[HDMA_MAX_WR_CH];
> +	struct dw_edma_region	ll_region_rd[HDMA_MAX_RD_CH];
>
>  	/* data region */
> -	struct dw_edma_region	dt_region_wr[EDMA_MAX_WR_CH];
> -	struct dw_edma_region	dt_region_rd[EDMA_MAX_RD_CH];
> +	struct dw_edma_region	dt_region_wr[HDMA_MAX_WR_CH];
> +	struct dw_edma_region	dt_region_rd[HDMA_MAX_RD_CH];
>
>  	/* interrupt emulation */
>  	int			db_irq;
> --
> 2.43.0
>

RE: [PATCH v3] dmaengine: dw-edma: Enable HDMA 64R/W Channels

[Verma, Devendra]

Public

> -----Original Message-----
> From: Frank Li <Frank.li@nxp.com>
> Sent: Friday, June 5, 2026 01:28
> To: Verma, Devendra <Devendra.Verma@amd.com>
> Cc: bhelgaas@google.com; mani@kernel.org; vkoul@kernel.org;
> Frank.Li@kernel.org; dmaengine@vger.kernel.org; linux-
> kernel@vger.kernel.org; Simek, Michal <michal.simek@amd.com>
> Subject: Re: [PATCH v3] dmaengine: dw-edma: Enable HDMA 64R/W
> Channels
>
> On Wed, Jun 03, 2026 at 08:11:47PM +0530, Devendra K Verma wrote:
> > As per 'Designware Cores PCI Express Controller Databook', Section 7.1
> > - Overview, HDMA supports 64 Read and 64 Write channels. Current
> > controller driver supports up to 8 read and write channels only. In
> > order to utilize all the channels the controller driver need to have
> > the channel related structs and variables as per the number of
> > channels supported by IP.
> > Following changes are made to enable 64 Read / 64 Write channel
> > support:
> >
> >  o Defined HDMA specific macros to reflect the channel count.
> >  o The count of ll_regions and dt_regions in dw_edma_chip and
> >    dw_edma_pcie_data shall be in accordance to number of read
> >    and write channels.
> >  o In dw_edma_probe() configure the channels as per the channels
> >    of the IP used.
> >  o Changed mask types to u64 for higher channel counts.
> >
> > Signed-off-by: Devendra K Verma <devendra.verma@amd.com>
> > ---
> > Changes in v2:
> >   o Fixed the pre-existing bug related to GET_CH_32
> >     interchanging the channel direction and id.
> >     This bug was not caused by any version of this patch.
> >   o Fixed the issue when using for_each_set_bit() for mask
> >     of u64 type.
> >
> > Changes in v1:
> >   o On review recommendation of sashiko bot, in the function
> >     dw_hdma_v0_core_off(), the loop iterates over registers
> >     as per the number of channels enabled and not on total
> >     number of channels supported.
> >   o Changed mask types to u64 for higher channel counts.
> > ---
> ...
> > +++ b/drivers/dma/dw-edma/dw-hdma-v0-core.c
> > @@ -53,13 +53,24 @@ __dw_ch_regs(struct dw_edma *dw, enum
> dw_edma_dir
> > dir, u16 ch)  static void dw_hdma_v0_core_off(struct dw_edma *dw)  {
> >     int id;
> > +   enum dw_edma_dir dir;
> > +
> > +   dir = EDMA_DIR_WRITE;
> > +   for (id = 0; id < dw->wr_ch_cnt; id++) {
> > +           SET_CH_32(dw, dir, id, int_setup,
> > +                     HDMA_V0_STOP_INT_MASK |
> HDMA_V0_ABORT_INT_MASK);
> > +           SET_CH_32(dw, dir, id, int_clear,
> > +                     HDMA_V0_STOP_INT_MASK |
> HDMA_V0_ABORT_INT_MASK);
> > +           SET_CH_32(dw, dir, id, ch_en, 0);
> > +   }
> >
> > -   for (id = 0; id < HDMA_V0_MAX_NR_CH; id++) {
> > -           SET_BOTH_CH_32(dw, id, int_setup,
> > -                          HDMA_V0_STOP_INT_MASK |
> HDMA_V0_ABORT_INT_MASK);
> > -           SET_BOTH_CH_32(dw, id, int_clear,
> > -                          HDMA_V0_STOP_INT_MASK |
> HDMA_V0_ABORT_INT_MASK);
> > -           SET_BOTH_CH_32(dw, id, ch_en, 0);
> > +   dir = EDMA_DIR_READ;
> > +   for (id = 0; id < dw->rd_ch_cnt; id++) {
> > +           SET_CH_32(dw, dir, id, int_setup,
> > +                     HDMA_V0_STOP_INT_MASK |
> HDMA_V0_ABORT_INT_MASK);
> > +           SET_CH_32(dw, dir, id, int_clear,
> > +                     HDMA_V0_STOP_INT_MASK |
> HDMA_V0_ABORT_INT_MASK);
> > +           SET_CH_32(dw, dir, id, ch_en, 0);
>
> why SET_BOTH_CH_32 not work for 64 channel?
>

SET_BOTH_CH_32 works, but this needs to be done on the channels enabled for the IP.
HDMA supports maximum of 64 channels. So if some IP enables 8 or fewer read / write channels only then the number of channels come from dw->wr_ch_cnt and dw->rd_ch_cnt. Now the logic is derived by individual read & write enabled channel count. Earlier, it was assumed that user will enable max of 8 channels which would have worked well using SET_BOTH_CH_32() but as the channels grow, the assumption that equal number of read / write channels and that they are set to max count are enabled might not hold true.

- Devendra

> >     }
> >  }
> >
> > @@ -79,7 +90,7 @@ static enum dma_status
> dw_hdma_v0_core_ch_status(struct dw_edma_chan *chan)
> >     u32 tmp;
> >
> >     tmp = FIELD_GET(HDMA_V0_CH_STATUS_MASK,
> > -                   GET_CH_32(dw, chan->id, chan->dir, ch_stat));
> > +                   GET_CH_32(dw, chan->dir, chan->id, ch_stat));
>
> why need swtich id and dir here ?
>
> Frank

This is the correct order of arguments to the GET_CH_32. The second & third arguments shall be direction and channel_id respectively. It is a pre-existing issue reported by AI bot.

> >
> >     if (tmp == 1)
> >             return DMA_IN_PROGRESS;
> > @@ -118,7 +129,8 @@ dw_hdma_v0_core_handle_int(struct dw_edma_irq
> *dw_irq, enum dw_edma_dir dir,
> >     unsigned long total, pos, val;
> >     irqreturn_t ret = IRQ_NONE;
> >     struct dw_edma_chan *chan;
> > -   unsigned long off, mask;
> > +   unsigned long off;
> > +   u64 mask;
> >
> >     if (dir == EDMA_DIR_WRITE) {
> >             total = dw->wr_ch_cnt;
> > @@ -130,7 +142,11 @@ dw_hdma_v0_core_handle_int(struct
> dw_edma_irq *dw_irq, enum dw_edma_dir dir,
> >             mask = dw_irq->rd_mask;
> >     }
> >
> > -   for_each_set_bit(pos, &mask, total) {
> > +   while (mask) {
> > +           pos = __ffs64(mask);
> > +           if (pos >= total)
> > +                   break;
> > +
> >             chan = &dw->chan[pos + off];
> >
> >             val = dw_hdma_v0_core_status_int(chan); @@ -147,6 +163,7
> @@
> > dw_hdma_v0_core_handle_int(struct dw_edma_irq *dw_irq, enum
> > dw_edma_dir dir,
> >
> >                     ret = IRQ_HANDLED;
> >             }
> > +           mask &= mask - 1;
> >     }
> >
> >     return ret;
> > diff --git a/drivers/dma/dw-edma/dw-hdma-v0-regs.h
> > b/drivers/dma/dw-edma/dw-hdma-v0-regs.h
> > index 7759ba9b4850..48e40efceb2e 100644
> > --- a/drivers/dma/dw-edma/dw-hdma-v0-regs.h
> > +++ b/drivers/dma/dw-edma/dw-hdma-v0-regs.h
> > @@ -11,7 +11,7 @@
> >
> >  #include <linux/dmaengine.h>
> >
> > -#define HDMA_V0_MAX_NR_CH                  8
> > +#define HDMA_V0_MAX_NR_CH                  64
> >  #define HDMA_V0_CH_EN                              BIT(0)
> >  #define HDMA_V0_LOCAL_ABORT_INT_EN         BIT(6)
> >  #define HDMA_V0_REMOTE_ABORT_INT_EN                BIT(5)
> > diff --git a/include/linux/dma/edma.h b/include/linux/dma/edma.h index
> > 1fafd5b0e315..da7a5cc93ad4 100644
> > --- a/include/linux/dma/edma.h
> > +++ b/include/linux/dma/edma.h
> > @@ -14,6 +14,8 @@
> >
> >  #define EDMA_MAX_WR_CH                                  8
> >  #define EDMA_MAX_RD_CH                                  8
> > +#define HDMA_MAX_WR_CH                                  64
> > +#define HDMA_MAX_RD_CH                                  64
> >
> >  struct dw_edma;
> >
> > @@ -89,12 +91,12 @@ struct dw_edma_chip {
> >     u16                     ll_wr_cnt;
> >     u16                     ll_rd_cnt;
> >     /* link list address */
> > -   struct dw_edma_region   ll_region_wr[EDMA_MAX_WR_CH];
> > -   struct dw_edma_region   ll_region_rd[EDMA_MAX_RD_CH];
> > +   struct dw_edma_region   ll_region_wr[HDMA_MAX_WR_CH];
> > +   struct dw_edma_region   ll_region_rd[HDMA_MAX_RD_CH];
> >
> >     /* data region */
> > -   struct dw_edma_region   dt_region_wr[EDMA_MAX_WR_CH];
> > -   struct dw_edma_region   dt_region_rd[EDMA_MAX_RD_CH];
> > +   struct dw_edma_region   dt_region_wr[HDMA_MAX_WR_CH];
> > +   struct dw_edma_region   dt_region_rd[HDMA_MAX_RD_CH];
> >
> >     /* interrupt emulation */
> >     int                     db_irq;
> > --
> > 2.43.0
> >

Re: [PATCH v3] dmaengine: dw-edma: Enable HDMA 64R/W Channels

[Frank Li]

On Fri, Jun 05, 2026 at 11:48:05AM +0000, Verma, Devendra wrote:
> Public
>
> > -----Original Message-----
> > From: Frank Li <Frank.li@nxp.com>
> > Sent: Friday, June 5, 2026 01:28
> > To: Verma, Devendra <Devendra.Verma@amd.com>
> > Cc: bhelgaas@google.com; mani@kernel.org; vkoul@kernel.org;
> > Frank.Li@kernel.org; dmaengine@vger.kernel.org; linux-
> > kernel@vger.kernel.org; Simek, Michal <michal.simek@amd.com>
> > Subject: Re: [PATCH v3] dmaengine: dw-edma: Enable HDMA 64R/W
> > Channels
> >
> > On Wed, Jun 03, 2026 at 08:11:47PM +0530, Devendra K Verma wrote:
> > > As per 'Designware Cores PCI Express Controller Databook', Section 7.1
> > > - Overview, HDMA supports 64 Read and 64 Write channels. Current
> > > controller driver supports up to 8 read and write channels only. In
> > > order to utilize all the channels the controller driver need to have
> > > the channel related structs and variables as per the number of
> > > channels supported by IP.
> > > Following changes are made to enable 64 Read / 64 Write channel
> > > support:
> > >
> > >  o Defined HDMA specific macros to reflect the channel count.
> > >  o The count of ll_regions and dt_regions in dw_edma_chip and
> > >    dw_edma_pcie_data shall be in accordance to number of read
> > >    and write channels.
> > >  o In dw_edma_probe() configure the channels as per the channels
> > >    of the IP used.
> > >  o Changed mask types to u64 for higher channel counts.
> > >
> > > Signed-off-by: Devendra K Verma <devendra.verma@amd.com>
> > > ---
> > > Changes in v2:
> > >   o Fixed the pre-existing bug related to GET_CH_32
> > >     interchanging the channel direction and id.
> > >     This bug was not caused by any version of this patch.
> > >   o Fixed the issue when using for_each_set_bit() for mask
> > >     of u64 type.
> > >
> > > Changes in v1:
> > >   o On review recommendation of sashiko bot, in the function
> > >     dw_hdma_v0_core_off(), the loop iterates over registers
> > >     as per the number of channels enabled and not on total
> > >     number of channels supported.
> > >   o Changed mask types to u64 for higher channel counts.
> > > ---
> > ...
> > > +++ b/drivers/dma/dw-edma/dw-hdma-v0-core.c
> > > @@ -53,13 +53,24 @@ __dw_ch_regs(struct dw_edma *dw, enum
> > dw_edma_dir
> > > dir, u16 ch)  static void dw_hdma_v0_core_off(struct dw_edma *dw)  {
> > >     int id;
> > > +   enum dw_edma_dir dir;
> > > +
> > > +   dir = EDMA_DIR_WRITE;
> > > +   for (id = 0; id < dw->wr_ch_cnt; id++) {
> > > +           SET_CH_32(dw, dir, id, int_setup,
> > > +                     HDMA_V0_STOP_INT_MASK |
> > HDMA_V0_ABORT_INT_MASK);
> > > +           SET_CH_32(dw, dir, id, int_clear,
> > > +                     HDMA_V0_STOP_INT_MASK |
> > HDMA_V0_ABORT_INT_MASK);
> > > +           SET_CH_32(dw, dir, id, ch_en, 0);
> > > +   }
> > >
> > > -   for (id = 0; id < HDMA_V0_MAX_NR_CH; id++) {
> > > -           SET_BOTH_CH_32(dw, id, int_setup,
> > > -                          HDMA_V0_STOP_INT_MASK |
> > HDMA_V0_ABORT_INT_MASK);
> > > -           SET_BOTH_CH_32(dw, id, int_clear,
> > > -                          HDMA_V0_STOP_INT_MASK |
> > HDMA_V0_ABORT_INT_MASK);
> > > -           SET_BOTH_CH_32(dw, id, ch_en, 0);
> > > +   dir = EDMA_DIR_READ;
> > > +   for (id = 0; id < dw->rd_ch_cnt; id++) {
> > > +           SET_CH_32(dw, dir, id, int_setup,
> > > +                     HDMA_V0_STOP_INT_MASK |
> > HDMA_V0_ABORT_INT_MASK);
> > > +           SET_CH_32(dw, dir, id, int_clear,
> > > +                     HDMA_V0_STOP_INT_MASK |
> > HDMA_V0_ABORT_INT_MASK);
> > > +           SET_CH_32(dw, dir, id, ch_en, 0);
> >
> > why SET_BOTH_CH_32 not work for 64 channel?
> >
>
> SET_BOTH_CH_32 works, but this needs to be done on the channels enabled for the IP.
> HDMA supports maximum of 64 channels. So if some IP enables 8 or fewer read / write channels only then the number of channels come from dw->wr_ch_cnt and dw->rd_ch_cnt. Now the logic is derived by individual read & write enabled channel count. Earlier, it was assumed that user will enable max of 8 channels which would have worked well using SET_BOTH_CH_32() but as the channels grow, the assumption that equal number of read / write channels and that they are set to max count are enabled might not hold true.

Make sense, please wrap your reply, it is hard to read

>
> - Devendra
>
> > >     }
> > >  }
> > >
> > > @@ -79,7 +90,7 @@ static enum dma_status
> > dw_hdma_v0_core_ch_status(struct dw_edma_chan *chan)
> > >     u32 tmp;
> > >
> > >     tmp = FIELD_GET(HDMA_V0_CH_STATUS_MASK,
> > > -                   GET_CH_32(dw, chan->id, chan->dir, ch_stat));
> > > +                   GET_CH_32(dw, chan->dir, chan->id, ch_stat));
> >
> > why need swtich id and dir here ?
> >
> > Frank
>
> This is the correct order of arguments to the GET_CH_32. The second & third arguments shall be direction and channel_id respectively. It is a pre-existing issue reported by AI bot.

AI found existing problem, need seperate patch to fix it.

Frank

Re: [PATCH v3] dmaengine: dw-edma: Enable HDMA 64R/W Channels

[Verma, Devendra]

On 05-Jun-26 23:45, Frank Li wrote:
> On Fri, Jun 05, 2026 at 11:48:05AM +0000, Verma, Devendra wrote:
>> Public
>>
>>> -----Original Message-----
>>> From: Frank Li <Frank.li@nxp.com>
>>> Sent: Friday, June 5, 2026 01:28
>>> To: Verma, Devendra <Devendra.Verma@amd.com>
>>> Cc: bhelgaas@google.com; mani@kernel.org; vkoul@kernel.org;
>>> Frank.Li@kernel.org; dmaengine@vger.kernel.org; linux-
>>> kernel@vger.kernel.org; Simek, Michal <michal.simek@amd.com>
>>> Subject: Re: [PATCH v3] dmaengine: dw-edma: Enable HDMA 64R/W
>>> Channels
>>>
>>> On Wed, Jun 03, 2026 at 08:11:47PM +0530, Devendra K Verma wrote:
>>>> As per 'Designware Cores PCI Express Controller Databook', Section 7.1
>>>> - Overview, HDMA supports 64 Read and 64 Write channels. Current
>>>> controller driver supports up to 8 read and write channels only. In
>>>> order to utilize all the channels the controller driver need to have
>>>> the channel related structs and variables as per the number of
>>>> channels supported by IP.
>>>> Following changes are made to enable 64 Read / 64 Write channel
>>>> support:
>>>>
>>>>   o Defined HDMA specific macros to reflect the channel count.
>>>>   o The count of ll_regions and dt_regions in dw_edma_chip and
>>>>     dw_edma_pcie_data shall be in accordance to number of read
>>>>     and write channels.
>>>>   o In dw_edma_probe() configure the channels as per the channels
>>>>     of the IP used.
>>>>   o Changed mask types to u64 for higher channel counts.
>>>>
>>>> Signed-off-by: Devendra K Verma <devendra.verma@amd.com>
>>>> ---
>>>> Changes in v2:
>>>>    o Fixed the pre-existing bug related to GET_CH_32
>>>>      interchanging the channel direction and id.
>>>>      This bug was not caused by any version of this patch.
>>>>    o Fixed the issue when using for_each_set_bit() for mask
>>>>      of u64 type.
>>>>
>>>> Changes in v1:
>>>>    o On review recommendation of sashiko bot, in the function
>>>>      dw_hdma_v0_core_off(), the loop iterates over registers
>>>>      as per the number of channels enabled and not on total
>>>>      number of channels supported.
>>>>    o Changed mask types to u64 for higher channel counts.
>>>> ---
>>> ...
>>>> +++ b/drivers/dma/dw-edma/dw-hdma-v0-core.c
>>>> @@ -53,13 +53,24 @@ __dw_ch_regs(struct dw_edma *dw, enum
>>> dw_edma_dir
>>>> dir, u16 ch)  static void dw_hdma_v0_core_off(struct dw_edma *dw)  {
>>>>      int id;
>>>> +   enum dw_edma_dir dir;
>>>> +
>>>> +   dir = EDMA_DIR_WRITE;
>>>> +   for (id = 0; id < dw->wr_ch_cnt; id++) {
>>>> +           SET_CH_32(dw, dir, id, int_setup,
>>>> +                     HDMA_V0_STOP_INT_MASK |
>>> HDMA_V0_ABORT_INT_MASK);
>>>> +           SET_CH_32(dw, dir, id, int_clear,
>>>> +                     HDMA_V0_STOP_INT_MASK |
>>> HDMA_V0_ABORT_INT_MASK);
>>>> +           SET_CH_32(dw, dir, id, ch_en, 0);
>>>> +   }
>>>>
>>>> -   for (id = 0; id < HDMA_V0_MAX_NR_CH; id++) {
>>>> -           SET_BOTH_CH_32(dw, id, int_setup,
>>>> -                          HDMA_V0_STOP_INT_MASK |
>>> HDMA_V0_ABORT_INT_MASK);
>>>> -           SET_BOTH_CH_32(dw, id, int_clear,
>>>> -                          HDMA_V0_STOP_INT_MASK |
>>> HDMA_V0_ABORT_INT_MASK);
>>>> -           SET_BOTH_CH_32(dw, id, ch_en, 0);
>>>> +   dir = EDMA_DIR_READ;
>>>> +   for (id = 0; id < dw->rd_ch_cnt; id++) {
>>>> +           SET_CH_32(dw, dir, id, int_setup,
>>>> +                     HDMA_V0_STOP_INT_MASK |
>>> HDMA_V0_ABORT_INT_MASK);
>>>> +           SET_CH_32(dw, dir, id, int_clear,
>>>> +                     HDMA_V0_STOP_INT_MASK |
>>> HDMA_V0_ABORT_INT_MASK);
>>>> +           SET_CH_32(dw, dir, id, ch_en, 0);
>>>
>>> why SET_BOTH_CH_32 not work for 64 channel?
>>>
>>
>> SET_BOTH_CH_32 works, but this needs to be done on the channels enabled for the IP.
>> HDMA supports maximum of 64 channels. So if some IP enables 8 or fewer read / write channels only then the number of channels come from dw->wr_ch_cnt and dw->rd_ch_cnt. Now the logic is derived by individual read & write enabled channel count. Earlier, it was assumed that user will enable max of 8 channels which would have worked well using SET_BOTH_CH_32() but as the channels grow, the assumption that equal number of read / write channels and that they are set to max count are enabled might not hold true.
> 
> Make sense, please wrap your reply, it is hard to read
> 

[Reformatted the comment to fit within the visible window]

SET_BOTH_CH_32 works, but this needs to be done on the channels enabled
for the IP. HDMA supports maximum of 64 channels. So, if some IP enables
8 or fewer read / write channels only, then the number of channels to be
configured shall come from dw->wr_ch_cnt and dw->rd_ch_cnt. In the new
code the logic is derived by individual read & write enabled channel
count. Earlier, it was assumed that user will enable max of 8 channels
which would have worked well using SET_BOTH_CH_32() but as the channels
grow, the assumption that equal number of read / write channels and that
they are set to max count are enabled might not hold true.

>>
>> - Devendra
>>
>>>>      }
>>>>   }
>>>>
>>>> @@ -79,7 +90,7 @@ static enum dma_status
>>> dw_hdma_v0_core_ch_status(struct dw_edma_chan *chan)
>>>>      u32 tmp;
>>>>
>>>>      tmp = FIELD_GET(HDMA_V0_CH_STATUS_MASK,
>>>> -                   GET_CH_32(dw, chan->id, chan->dir, ch_stat));
>>>> +                   GET_CH_32(dw, chan->dir, chan->id, ch_stat));
>>>
>>> why need swtich id and dir here ?
>>>
>>> Frank
>>
>> This is the correct order of arguments to the GET_CH_32. The second & third arguments shall be direction and channel_id respectively. It is a pre-existing issue reported by AI bot.
> 
> AI found existing problem, need seperate patch to fix it.
> 
> Frank

Removed this fix. Will include it as part of separate series.
I will upload the next version with the above recommendation.

-Devendra