[PATCH v4 0/4] OMAP2/3: DMA: FIFO drain errata fixes

[PATCH v4 0/4] OMAP2/3: DMA: FIFO drain errata fixes

[Peter Ujfalusi]

Hello,

Changes since v3:
- use flags for errata handling
 - OMAP2 buffering disable converted to use flags
 - OMAP3 i541 is using the dma_errata flag
- Spelling fix in OMAP3 drain timeout message
Changes since v2:
- remove multiple assignment
Changes since v1:
- Errata ID added to the comment (i541)

Intro mail from v1:

The following series fixes the sDMA FIFO drain issue present for OMAP2 and
OMAP3, and covered by an errata.
For OMAP2 the omap_start_dma had a comment about this errata, but the workaround
configured wrong bit (CCR_EN instead of the correct BUFFERING_DISABLE bit).
The first patch from Jarkko Nikula <jhnikula@gmail.com> fixes this.
For OMAP3 the suggestion is to set sDMA to NoStandby before disabling
the channel, and wait for the drain to finish, than configure sDMA to
SmartStandby again. The second patch implements this workaround for OMAP3.

The FIFO drain problem can be reproduced on both OMAP2 and OMAP3 while using
audio (capture case):
Either introduce load to the CPU:
nice -19 arecord -D hw:0 -M -B 10000 -F 5000 -f dat > /dev/null & \
dd if=/dev/urandom of=/dev/null

or suspending the arecord, and resuming it:
arecord -D hw:0 -M -B 10000 -F 5000 -f dat > /dev/null
CTRL+Z; fg; CTRL+Z; fg; ...

On OMAP2 we can not recover from this problem. The board has to be rebooted,
while OMAP3 can be recovered by reseting the sDMA channel, or introducing
unrelated sDMA activity (which takes sDMA out from Standby - but this is not
working all the time).

---
Peter Ujfalusi (3):
  OMAP: DMA: Introduce errata handling variable, and macro
  OMAP2: DMA: Use errata flag for disabling buffering
  OMAP3: DMA: Errata i541: sDMA FIFO draining does not finish

ext Jarkko Nikula (1):
  omap: dma: Fix buffering disable bit setting for omap24xx

 arch/arm/plat-omap/dma.c              |   60 ++++++++++++++++++++++++++++++--
 arch/arm/plat-omap/include/plat/dma.h |    4 ++
 2 files changed, 60 insertions(+), 4 deletions(-)

--
1.7.3

[PATCH v4 1/4] omap: dma: Fix buffering disable bit setting for omap24xx

[Peter Ujfalusi]

From: ext Jarkko Nikula <jhnikula@gmail.com>

An errata workaround for omap24xx is not setting the buffering disable bit
25 what is the purpose but channel enable bit 7 instead.

Background for this fix is the DMA stalling issue with ASoC omap-mcbsp
driver. Peter Ujfalusi <peter.ujfalusi@nokia.com> has found an issue in
recording that the DMA stall could happen if there were a buffer overrun
detected by ALSA and the DMA was stopped and restarted due that. This
problem is known to occur on both OMAP2420 and OMAP3. It can recover on
OMAP3 after dma free, dma request and reconfiguration cycle. However, on
OMAP2420 it seems that only way to recover is a reset.

Problem was not visible before the commit c12abc0. That commit changed that
the McBSP transmitter/receiver is released from reset only when needed. That
is, only enabled McBSP transmitter without transmission was able to prevent
this DMA stall problem in receiving side and underlying problem did not show
up until now. McBSP transmitter itself seems to no be reason since DMA
stall does not recover by enabling the transmission after stall.

Debugging showed that there were a DMA write active during DMA stop time and
it never completed even when restarting the DMA. Experimenting showed that
the DMA buffering disable bit could be used to avoid stalling when using
source synchronized transfers. However that could have performance hit and
OMAP3 TRM states that buffering disable is not allowed for destination
synchronized transfers so subsequent patch will implement a method to
complete DMA writes when stopping.

This patch is based on assumtion that complete lock-up on OMAP2420 is
different but related problem. I don't have access to OMAP2420 errata but
I believe this old workaround here is put for a reason but unfortunately
a wrong bit was typed and problem showed up only now.

v2: Issue is applicaple only to OMAP2420 and ES1.0 of OMAP2430. Thanks to
G, Manjunath Kondaiah <manjugk@ti.com> for noticing.

Signed-off-by: Jarkko Nikula <jhnikula@gmail.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
---
 arch/arm/plat-omap/dma.c              |    5 +++--
 arch/arm/plat-omap/include/plat/dma.h |    1 +
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
index ec7eddf..6914ccf 100644
--- a/arch/arm/plat-omap/dma.c
+++ b/arch/arm/plat-omap/dma.c
@@ -999,8 +999,9 @@ void omap_start_dma(int lch)
 	 * Errata: On ES2.0 BUFFERING disable must be set.
 	 * This will always fail on ES1.0
 	 */
-	if (cpu_is_omap24xx())
-		l |= OMAP_DMA_CCR_EN;
+	if (cpu_is_omap2420() ||
+	    (cpu_is_omap2430() && (omap_type() == OMAP2430_REV_ES1_0)))
+		l |= OMAP_DMA_CCR_BUFFERING_DISABLE;
 
 	l |= OMAP_DMA_CCR_EN;
 	dma_write(l, CCR(lch));
diff --git a/arch/arm/plat-omap/include/plat/dma.h b/arch/arm/plat-omap/include/plat/dma.h
index af3a039..776ba44 100644
--- a/arch/arm/plat-omap/include/plat/dma.h
+++ b/arch/arm/plat-omap/include/plat/dma.h
@@ -335,6 +335,7 @@
 #define OMAP2_DMA_MISALIGNED_ERR_IRQ	(1 << 11)
 
 #define OMAP_DMA_CCR_EN			(1 << 7)
+#define OMAP_DMA_CCR_BUFFERING_DISABLE	(1 << 25)
 
 #define OMAP_DMA_DATA_TYPE_S8		0x00
 #define OMAP_DMA_DATA_TYPE_S16		0x01
-- 
1.7.3

[PATCH v4 1/4] omap: dma: Fix buffering disable bit setting for omap24xx

[G, Manjunath Kondaiah]

> -----Original Message-----
> From: linux-omap-owner at vger.kernel.org 
> [mailto:linux-omap-owner at vger.kernel.org] On Behalf Of Peter Ujfalusi
> Sent: Monday, October 04, 2010 1:48 PM
> To: Tony Lindgren
> Cc: linux-omap at vger.kernel.org; Jarkko Nikula; 
> linux-arm-kernel at lists.infradead.org
> Subject: [PATCH v4 1/4] omap: dma: Fix buffering disable bit 
> setting for omap24xx
> 
> From: ext Jarkko Nikula <jhnikula@gmail.com>
> 
> An errata workaround for omap24xx is not setting the 
> buffering disable bit
> 25 what is the purpose but channel enable bit 7 instead.

...

> diff --git a/arch/arm/plat-omap/dma.c 
> b/arch/arm/plat-omap/dma.c index ec7eddf..6914ccf 100644
> --- a/arch/arm/plat-omap/dma.c
> +++ b/arch/arm/plat-omap/dma.c
> @@ -999,8 +999,9 @@ void omap_start_dma(int lch)
>  	 * Errata: On ES2.0 BUFFERING disable must be set.
>  	 * This will always fail on ES1.0
>  	 */

Sorry, I didn't catch this with earlier patch.

Looks like wrong comment. only on 2430ES1.0 and for all omap2420, 
buffer disable should be set. 
I feel below description will be useful to the reader:
"Errata: Inter Frame DMA buffering issue(All OMAP2420 and OMAP2430ES1.0):
DMA will wrongly buffer elements if packing and bursting is enabled.
This might result in data gets stalled in FIFO at the end of the block.
Workaround: DMA channels must have BUFFERING_DISABLED bit set to guarantee
no data will stay in the DMA FIFO in case inter frame buffering occurs.


-Manjunath

[PATCH v4 1/4] omap: dma: Fix buffering disable bit setting for omap24xx

[Jarkko Nikula]

On Mon, 4 Oct 2010 14:44:28 +0530
"G, Manjunath Kondaiah" <manjugk@ti.com> wrote:

> 
> 
> > -----Original Message-----
> > From: linux-omap-owner at vger.kernel.org 
> > [mailto:linux-omap-owner at vger.kernel.org] On Behalf Of Peter Ujfalusi
> > Sent: Monday, October 04, 2010 1:48 PM
> > To: Tony Lindgren
> > Cc: linux-omap at vger.kernel.org; Jarkko Nikula; 
> > linux-arm-kernel at lists.infradead.org
> > Subject: [PATCH v4 1/4] omap: dma: Fix buffering disable bit 
> > setting for omap24xx
> > 
> > From: ext Jarkko Nikula <jhnikula@gmail.com>
> > 
> > An errata workaround for omap24xx is not setting the 
> > buffering disable bit
> > 25 what is the purpose but channel enable bit 7 instead.
> 
> ...
> 
> > diff --git a/arch/arm/plat-omap/dma.c 
> > b/arch/arm/plat-omap/dma.c index ec7eddf..6914ccf 100644
> > --- a/arch/arm/plat-omap/dma.c
> > +++ b/arch/arm/plat-omap/dma.c
> > @@ -999,8 +999,9 @@ void omap_start_dma(int lch)
> >  	 * Errata: On ES2.0 BUFFERING disable must be set.
> >  	 * This will always fail on ES1.0
> >  	 */
> 
> Sorry, I didn't catch this with earlier patch.
> 
> Looks like wrong comment. only on 2430ES1.0 and for all omap2420, 
> buffer disable should be set. 
> I feel below description will be useful to the reader:
> "Errata: Inter Frame DMA buffering issue(All OMAP2420 and OMAP2430ES1.0):
> DMA will wrongly buffer elements if packing and bursting is enabled.
> This might result in data gets stalled in FIFO at the end of the block.
> Workaround: DMA channels must have BUFFERING_DISABLED bit set to guarantee
> no data will stay in the DMA FIFO in case inter frame buffering occurs.
> 
Ok, no problem. I'll add this to the next version. This is good to get
documented.


-- 
Jarkko

[PATCH v4 2/4] OMAP: DMA: Introduce errata handling variable, and macro

[Peter Ujfalusi]

Use flags for errata handling.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
---
 arch/arm/plat-omap/dma.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
index 6914ccf..ae0ff64 100644
--- a/arch/arm/plat-omap/dma.c
+++ b/arch/arm/plat-omap/dma.c
@@ -146,6 +146,10 @@ static const u8 omap1_dma_irq[OMAP1_LOGICAL_DMA_CH_COUNT] = {
 	INT_1610_DMA_CH14, INT_1610_DMA_CH15, INT_DMA_LCD
 };
 
+/* Errata handling */
+static u16 dma_errata;
+#define IS_DMA_ERRATA(id)	(dma_errata & (id))
+
 static inline void disable_lnk(int lch);
 static void omap_disable_channel_irq(int lch);
 static inline void omap_enable_channel_irq(int lch);
@@ -2042,6 +2046,10 @@ void omap_dma_global_context_restore(void)
 
 /*----------------------------------------------------------------------------*/
 
+static void dma_errata_configure(void)
+{
+}
+
 static int __init omap_init_dma(void)
 {
 	unsigned long base;
@@ -2064,6 +2072,8 @@ static int __init omap_init_dma(void)
 		return -ENODEV;
 	}
 
+	dma_errata_configure();
+
 	omap_dma_base = ioremap(base, SZ_4K);
 	BUG_ON(!omap_dma_base);
 
-- 
1.7.3

[PATCH v4 3/4] OMAP2: DMA: Use errata flag for disabling buffering

[Peter Ujfalusi]

Convert the errata handling of buffering disable on
OMAP2 platforms.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
---
 arch/arm/plat-omap/dma.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
index ae0ff64..c116c41 100644
--- a/arch/arm/plat-omap/dma.c
+++ b/arch/arm/plat-omap/dma.c
@@ -147,6 +147,7 @@ static const u8 omap1_dma_irq[OMAP1_LOGICAL_DMA_CH_COUNT] = {
 };
 
 /* Errata handling */
+#define DMA_ERRATA_IFRAME_BUFFERING	(1 << 0)
 static u16 dma_errata;
 #define IS_DMA_ERRATA(id)	(dma_errata & (id))
 
@@ -1003,8 +1004,7 @@ void omap_start_dma(int lch)
 	 * Errata: On ES2.0 BUFFERING disable must be set.
 	 * This will always fail on ES1.0
 	 */
-	if (cpu_is_omap2420() ||
-	    (cpu_is_omap2430() && (omap_type() == OMAP2430_REV_ES1_0)))
+	if (IS_DMA_ERRATA(DMA_ERRATA_IFRAME_BUFFERING))
 		l |= OMAP_DMA_CCR_BUFFERING_DISABLE;
 
 	l |= OMAP_DMA_CCR_EN;
@@ -2048,6 +2048,9 @@ void omap_dma_global_context_restore(void)
 
 static void dma_errata_configure(void)
 {
+	if (cpu_is_omap2420() ||
+	    (cpu_is_omap2430() && (omap_type() == OMAP2430_REV_ES1_0)))
+		dma_errata |= DMA_ERRATA_IFRAME_BUFFERING;
 }
 
 static int __init omap_init_dma(void)
-- 
1.7.3

[PATCH v4 3/4] OMAP2: DMA: Use errata flag for disabling buffering

[G, Manjunath Kondaiah]

 

> -----Original Message-----
> From: linux-omap-owner at vger.kernel.org 
> [mailto:linux-omap-owner at vger.kernel.org] On Behalf Of Peter Ujfalusi
> Sent: Monday, October 04, 2010 1:48 PM
> To: Tony Lindgren
> Cc: linux-omap at vger.kernel.org; Jarkko Nikula; 
> linux-arm-kernel at lists.infradead.org
> Subject: [PATCH v4 3/4] OMAP2: DMA: Use errata flag for 
> disabling buffering

...

>  
>  /* Errata handling */
> +#define DMA_ERRATA_IFRAME_BUFFERING	(1 << 0)
>  static u16 dma_errata;
>  #define IS_DMA_ERRATA(id)	(dma_errata & (id))
>  

These macros should move to header file since these
macros will be used in mach-omap2/dma.c and plat-omap/dma.c
with upcoming dma hwmod series.

-Manjunath

[PATCH v4 4/4] OMAP3: DMA: Errata i541: sDMA FIFO draining does not finish

[Peter Ujfalusi]

Implement the suggested workaround for OMAP3 regarding to sDMA draining
issue, when the channel is disabled on the fly.
This errata affects the following configuration:
sDMA transfer is source synchronized
Buffering is enabled
SmartStandby is selected.

The issue can be easily reproduced by creating overrun situation while
recording audio.
Either introduce load to the CPU:
nice -19 arecord -D hw:0 -M -B 10000 -F 5000 -f dat > /dev/null & \
dd if=/dev/urandom of=/dev/null

or suspending the arecord, and resuming it:
arecord -D hw:0 -M -B 10000 -F 5000 -f dat > /dev/null
CTRL+Z; fg; CTRL+Z; fg; ...

In case of overrun audio stops DMA, and restarts it (without reseting
the sDMA channel). When we hit this errata in stop case (sDMA drain did
not complete), at the coming start the sDMA will not going to be
operational (it is still draining).
This leads to DMA stall condition.
On OMAP3 we can recover with sDMA channel reset, it has been observed
that by introducing unrelated sDMA activity might also help (reading
from MMC for example).

The same errata exists for OMAP2, where the suggestion is to disable the
buffering to avoid this type of error.
On OMAP3 the suggestion is to set sDMA to NoStandby before disabling
the channel, and wait for the drain to finish, than configure sDMA to
SmartStandby again.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
Acked-by: Jarkko Nikula <jhnikula@gmail.com>
Acked-by : Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by : G, Manjunath Kondaiah <manjugk@ti.com>
---
 arch/arm/plat-omap/dma.c              |   42 +++++++++++++++++++++++++++++++-
 arch/arm/plat-omap/include/plat/dma.h |    3 ++
 2 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
index c116c41..a102cf5 100644
--- a/arch/arm/plat-omap/dma.c
+++ b/arch/arm/plat-omap/dma.c
@@ -30,6 +30,7 @@
 #include <linux/irq.h>
 #include <linux/io.h>
 #include <linux/slab.h>
+#include <linux/delay.h>
 
 #include <asm/system.h>
 #include <mach/hardware.h>
@@ -148,6 +149,8 @@ static const u8 omap1_dma_irq[OMAP1_LOGICAL_DMA_CH_COUNT] = {
 
 /* Errata handling */
 #define DMA_ERRATA_IFRAME_BUFFERING	(1 << 0)
+/* OMAP3 Errata i541: sDMA FIFO draining does not finish */
+#define DMA_ERRATA_i541			(1 << 1)
 static u16 dma_errata;
 #define IS_DMA_ERRATA(id)	(dma_errata & (id))
 
@@ -1023,8 +1026,40 @@ void omap_stop_dma(int lch)
 		dma_write(0, CICR(lch));
 
 	l = dma_read(CCR(lch));
-	l &= ~OMAP_DMA_CCR_EN;
-	dma_write(l, CCR(lch));
+	/* OMAP3 Errata i541: sDMA FIFO draining does not finish */
+	if (IS_DMA_ERRATA(DMA_ERRATA_i541) &&
+	    (l & OMAP_DMA_CCR_SEL_SRC_DST_SYNC)) {
+		int i = 0;
+		u32 sys_cf;
+
+		/* Configure No-Standby */
+		l = dma_read(OCP_SYSCONFIG);
+		sys_cf = l;
+		l &= ~DMA_SYSCONFIG_MIDLEMODE_MASK;
+		l |= DMA_SYSCONFIG_MIDLEMODE(DMA_IDLEMODE_NO_IDLE);
+		dma_write(l , OCP_SYSCONFIG);
+
+		l = dma_read(CCR(lch));
+		l &= ~OMAP_DMA_CCR_EN;
+		dma_write(l, CCR(lch));
+
+		/* Wait for sDMA FIFO drain */
+		l = dma_read(CCR(lch));
+		while (i < 100 && (l & (OMAP_DMA_CCR_RD_ACTIVE |
+					OMAP_DMA_CCR_WR_ACTIVE))) {
+			udelay(5);
+			i++;
+			l = dma_read(CCR(lch));
+		}
+		if (i >= 100)
+			printk(KERN_ERR "DMA drain did not complete on "
+					"lch %d\n", lch);
+		/* Restore OCP_SYSCONFIG */
+		dma_write(sys_cf, OCP_SYSCONFIG);
+	} else {
+		l &= ~OMAP_DMA_CCR_EN;
+		dma_write(l, CCR(lch));
+	}
 
 	if (!omap_dma_in_1510_mode() && dma_chan[lch].next_lch != -1) {
 		int next_lch, cur_lch = lch;
@@ -2051,6 +2086,9 @@ static void dma_errata_configure(void)
 	if (cpu_is_omap2420() ||
 	    (cpu_is_omap2430() && (omap_type() == OMAP2430_REV_ES1_0)))
 		dma_errata |= DMA_ERRATA_IFRAME_BUFFERING;
+
+	if (cpu_is_omap34xx())
+		dma_errata |= DMA_ERRATA_i541;
 }
 
 static int __init omap_init_dma(void)
diff --git a/arch/arm/plat-omap/include/plat/dma.h b/arch/arm/plat-omap/include/plat/dma.h
index 776ba44..cf66f85 100644
--- a/arch/arm/plat-omap/include/plat/dma.h
+++ b/arch/arm/plat-omap/include/plat/dma.h
@@ -335,6 +335,9 @@
 #define OMAP2_DMA_MISALIGNED_ERR_IRQ	(1 << 11)
 
 #define OMAP_DMA_CCR_EN			(1 << 7)
+#define OMAP_DMA_CCR_RD_ACTIVE		(1 << 9)
+#define OMAP_DMA_CCR_WR_ACTIVE		(1 << 10)
+#define OMAP_DMA_CCR_SEL_SRC_DST_SYNC	(1 << 24)
 #define OMAP_DMA_CCR_BUFFERING_DISABLE	(1 << 25)
 
 #define OMAP_DMA_DATA_TYPE_S8		0x00
-- 
1.7.3

[PATCH v4 4/4] OMAP3: DMA: Errata i541: sDMA FIFO draining does not finish

[G, Manjunath Kondaiah]

> -----Original Message-----
> From: linux-omap-owner at vger.kernel.org 
> [mailto:linux-omap-owner at vger.kernel.org] On Behalf Of Peter Ujfalusi
> Sent: Monday, October 04, 2010 1:48 PM
> To: Tony Lindgren
> Cc: linux-omap at vger.kernel.org; Jarkko Nikula; 
> linux-arm-kernel at lists.infradead.org
> Subject: [PATCH v4 4/4] OMAP3: DMA: Errata i541: sDMA FIFO 
> draining does not finish
>
...
> +	/* OMAP3 Errata i541: sDMA FIFO draining does not finish */

This logic is required for multiple erratas. Can we have seperate
function for handling this logic. More details at:
https://patchwork.kernel.org/patch/126271/

...

> --- a/arch/arm/plat-omap/include/plat/dma.h
> +++ b/arch/arm/plat-omap/include/plat/dma.h
> @@ -335,6 +335,9 @@
>  #define OMAP2_DMA_MISALIGNED_ERR_IRQ	(1 << 11)
>  
>  #define OMAP_DMA_CCR_EN			(1 << 7)
> +#define OMAP_DMA_CCR_RD_ACTIVE		(1 << 9)
> +#define OMAP_DMA_CCR_WR_ACTIVE		(1 << 10)
> +#define OMAP_DMA_CCR_SEL_SRC_DST_SYNC	(1 << 24)
>  #define OMAP_DMA_CCR_BUFFERING_DISABLE	(1 << 25)

As I mentioned in other mail, if you are introducing this feature,
it is better to convert existing erratas also to use this feature.

-Manjunath

[PATCH v4 4/4] OMAP3: DMA: Errata i541: sDMA FIFO draining does not finish

[Peter Ujfalusi]

On Monday 04 October 2010 12:17:41 ext G, Manjunath Kondaiah wrote:
> 
> ...
> 
> > +	/* OMAP3 Errata i541: sDMA FIFO draining does not finish */
> 
> This logic is required for multiple erratas.

As Tony requested, I have added a variable for flags to handle the different 
erratas. I even added a macro to check that the errata applies, so one can use:
if (IS_DMA_ERRATA(DMA_ERRATA_XXXXX))

> Can we have seperate
> function for handling this logic. More details at:
> https://patchwork.kernel.org/patch/126271/

I see. That patch is for hwmod converted dma code, right?
We need this fix without the hwmod to applied, and than backport it to earlier 
kernel releases.

> As I mentioned in other mail, if you are introducing this feature,
> it is better to convert existing erratas also to use this feature.

The upcoming hwmod conversion will take care of the cleanup.
We _need_ these two small fixes ASAP, since it is fixing serious problem in 
audio (and the same issue might bite other areas as well).
It is not the intention of this series to clean up the arc/arm/plat-omap/dma.c.

I have added the dma_errata variable, since Tony asked for it, but even that 
addition is a bigger change than what I was planning to do here.

-- 
P?ter

[PATCH v4 4/4] OMAP3: DMA: Errata i541: sDMA FIFO draining does not finish

[G, Manjunath Kondaiah]

> -----Original Message-----
> From: Peter Ujfalusi [mailto:peter.ujfalusi at nokia.com] 
> Sent: Monday, October 04, 2010 4:13 PM
> To: G, Manjunath Kondaiah
> Cc: Tony Lindgren; linux-omap at vger.kernel.org; Jarkko Nikula; 
> linux-arm-kernel at lists.infradead.org
> Subject: Re: [PATCH v4 4/4] OMAP3: DMA: Errata i541: sDMA 
> FIFO draining does not finish
> 
> On Monday 04 October 2010 12:17:41 ext G, Manjunath Kondaiah wrote:
> > 
> > ...
> > 
> > > +	/* OMAP3 Errata i541: sDMA FIFO draining does not finish */
> > 
> > This logic is required for multiple erratas.
> 
> As Tony requested, I have added a variable for flags to 
> handle the different erratas. I even added a macro to check 
> that the errata applies, so one can use:
> if (IS_DMA_ERRATA(DMA_ERRATA_XXXXX))
> 
> > Can we have seperate
> > function for handling this logic. More details at:
> > https://patchwork.kernel.org/patch/126271/
> 
> I see. That patch is for hwmod converted dma code, right?
> We need this fix without the hwmod to applied, and than 
> backport it to earlier kernel releases.
> 
> > As I mentioned in other mail, if you are introducing this 
> feature, it 
> > is better to convert existing erratas also to use this feature.
> 
> The upcoming hwmod conversion will take care of the cleanup.

If this is the case, not sure about intention of having dma_errata only
for these two erratas since all the erratas are not handled.

All the erratas will get cleaned up and errata handling feature
will be introduced along with dma hwmod changes.

If feel v3 version is better so that I can use these changes along 
dma hwmod.

It is upto Tony to decide.

> We _need_ these two small fixes ASAP, since it is fixing 
> serious problem in audio (and the same issue might bite other 
> areas as well).
> It is not the intention of this series to clean up the 
> arc/arm/plat-omap/dma.c.

Tony, 
How about having v3 series + review comments fixed(except comments
related errata handling). Errata handling will be done as part dma
hwmod. I am waiting for these patches so that I can rebase these
patches in DMA hwmod.

-Manjunath

[PATCH v4 4/4] OMAP3: DMA: Errata i541: sDMA FIFO draining does not finish

[Tony Lindgren]

* Peter Ujfalusi <peter.ujfalusi@nokia.com> [101004 03:33]:
> On Monday 04 October 2010 12:17:41 ext G, Manjunath Kondaiah wrote:
> > 
> > ...
> > 
> > > +	/* OMAP3 Errata i541: sDMA FIFO draining does not finish */
> > 
> > This logic is required for multiple erratas.
> 
> As Tony requested, I have added a variable for flags to handle the different 
> erratas. I even added a macro to check that the errata applies, so one can use:
> if (IS_DMA_ERRATA(DMA_ERRATA_XXXXX))
> 
> > Can we have seperate
> > function for handling this logic. More details at:
> > https://patchwork.kernel.org/patch/126271/
> 
> I see. That patch is for hwmod converted dma code, right?
> We need this fix without the hwmod to applied, and than backport it to earlier 
> kernel releases.
> 
> > As I mentioned in other mail, if you are introducing this feature,
> > it is better to convert existing erratas also to use this feature.
> 
> The upcoming hwmod conversion will take care of the cleanup.
> We _need_ these two small fixes ASAP, since it is fixing serious problem in 
> audio (and the same issue might bite other areas as well).
> It is not the intention of this series to clean up the arc/arm/plat-omap/dma.c.
> 
> I have added the dma_errata variable, since Tony asked for it, but even that 
> addition is a bigger change than what I was planning to do here.

Yeah.. Let's just use your original patch for the fix, then queue
adding the errata flag for the upcoming merge window.

Regards,

Tony

[PATCH v4 0/4] OMAP2/3: DMA: FIFO drain errata fixes

[Peter Ujfalusi]

Hello,

Will resend, since

On Monday 04 October 2010 11:18:10 ext Peter Ujfalusi wrote:

...

> ext Jarkko Nikula (1):
>   omap: dma: Fix buffering disable bit setting for omap24xx

Our mail server changed Jarkko's name.
Sorry.

-- 
P?ter

[PATCH v4 0/4] OMAP2/3: DMA: FIFO drain errata fixes

[Peter Ujfalusi]

On Monday 04 October 2010 11:29:16 ext Peter Ujfalusi wrote:
> Hello,
> 
> Will resend, since

I'll wait for comments on v4 series, and I'll send the v5 later today after the 
comments to reduce the noise.

-- 
P?ter

[PATCH v4 0/4] OMAP2/3: DMA: FIFO drain errata fixes

[Tony Lindgren]

* Peter Ujfalusi <peter.ujfalusi@nokia.com> [101004 01:26]:
> On Monday 04 October 2010 11:29:16 ext Peter Ujfalusi wrote:
> > Hello,
> > 
> > Will resend, since
> 
> I'll wait for comments on v4 series, and I'll send the v5 later today after the 
> comments to reduce the noise.

Looks like we should have the minimal two patches to queue as fixes
for v2.6.36, then queue the errata flag changes for the upcoming
merge window.

Regards,

Tony