[PATCH v2 0/2] dmaengine: at_hdmac: Regression fix and cleanup

[PATCH v2 0/2] dmaengine: at_hdmac: Regression fix and cleanup

[Peter Rosin]

Hi!

I found a regression in DMA handling on one of our SAMA5D3 boards.

While combing through the regressing commit, a found two unrelated
strange things. The first is the actually problematic change. The
second is a number of suspect defines, that I fail to see how they
can ever do any good.

Cheers,
Peter

Changes since v1 [1], after comments from Tudor Ambarus:

Patch 1/2:
- Don't convert to inline functions.
- Cc stable

Patch 2/2:
- Extend the field instead of killing "too big" field values.
- Add Fixes and R-b tags.
- Cc stable

[1] https://lore.kernel.org/lkml/dc4834cb-fadf-17a5-fbc7-cf500db88f20@axentia.se/


Peter Rosin (2):
  dmaengine: at_hdmac: Repair bitfield macros for peripheral ID handling
  dmaengine: at_hdmac: Extend the Flow Controller bitfield to three bits

 drivers/dma/at_hdmac.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

-- 
2.20.1


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[PATCH v2 1/2] dmaengine: at_hdmac: Repair bitfield macros for peripheral ID handling

[Peter Rosin]

The MSB part of the peripheral IDs need to go into the ATC_SRC_PER_MSB
and ATC_DST_PER_MSB fields. Not the LSB part.

This fixes a severe regression for TSE-850 devices (compatible
axentia,tse850v3) where output to the audio I2S codec (the main
purpose of the device) simply do not work.

Fixes: d8840a7edcf0 ("dmaengine: at_hdmac: Use bitfield access macros")
Cc: stable@vger.kernel.org
Signed-off-by: Peter Rosin <peda@axentia.se>
---
 drivers/dma/at_hdmac.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 8858470246e1..6362013b90df 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -153,8 +153,6 @@
 #define ATC_AUTO		BIT(31)		/* Auto multiple buffer tx enable */
 
 /* Bitfields in CFG */
-#define ATC_PER_MSB(h)	((0x30U & (h)) >> 4)	/* Extract most significant bits of a handshaking identifier */
-
 #define ATC_SRC_PER		GENMASK(3, 0)	/* Channel src rq associated with periph handshaking ifc h */
 #define ATC_DST_PER		GENMASK(7, 4)	/* Channel dst rq associated with periph handshaking ifc h */
 #define ATC_SRC_REP		BIT(8)		/* Source Replay Mod */
@@ -181,10 +179,15 @@
 #define ATC_DPIP_HOLE		GENMASK(15, 0)
 #define ATC_DPIP_BOUNDARY	GENMASK(25, 16)
 
-#define ATC_SRC_PER_ID(id)	(FIELD_PREP(ATC_SRC_PER_MSB, (id)) |	\
-				 FIELD_PREP(ATC_SRC_PER, (id)))
-#define ATC_DST_PER_ID(id)	(FIELD_PREP(ATC_DST_PER_MSB, (id)) |	\
-				 FIELD_PREP(ATC_DST_PER, (id)))
+#define ATC_PER_MSB		GENMASK(5, 4)	/* Extract MSBs of a handshaking identifier */
+#define ATC_SRC_PER_ID(id)					       \
+	({ typeof(id) _id = (id);				       \
+	   FIELD_PREP(ATC_SRC_PER_MSB, FIELD_GET(ATC_PER_MSB, _id)) |  \
+	   FIELD_PREP(ATC_SRC_PER, _id); })
+#define ATC_DST_PER_ID(id)					       \
+	({ typeof(id) _id = (id);				       \
+	   FIELD_PREP(ATC_DST_PER_MSB, FIELD_GET(ATC_PER_MSB, _id)) |  \
+	   FIELD_PREP(ATC_DST_PER, _id); })
 
 
 
-- 
2.20.1


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[PATCH v2 2/2] dmaengine: at_hdmac: Extend the Flow Controller bitfield to three bits

[Peter Rosin]

Some chips have two bits (e.g SAMA5D3), and some have three (e.g.
SAM9G45). A field width of three is compatible as long as valid
values are used for the different chips.

There is no current use of any value needing three bits, so the
fixed bug is relatively benign.

Fixes: d8840a7edcf0 ("dmaengine: at_hdmac: Use bitfield access macros")
Cc: stable@vger.kernel.org
Reviewed-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Signed-off-by: Peter Rosin <peda@axentia.se>
---
 drivers/dma/at_hdmac.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 6362013b90df..ee3a219e3a89 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -132,7 +132,7 @@
 #define ATC_DST_PIP		BIT(12)		/* Destination Picture-in-Picture enabled */
 #define ATC_SRC_DSCR_DIS	BIT(16)		/* Src Descriptor fetch disable */
 #define ATC_DST_DSCR_DIS	BIT(20)		/* Dst Descriptor fetch disable */
-#define ATC_FC			GENMASK(22, 21)	/* Choose Flow Controller */
+#define ATC_FC			GENMASK(23, 21)	/* Choose Flow Controller */
 #define ATC_FC_MEM2MEM		0x0		/* Mem-to-Mem (DMA) */
 #define ATC_FC_MEM2PER		0x1		/* Mem-to-Periph (DMA) */
 #define ATC_FC_PER2MEM		0x2		/* Periph-to-Mem (DMA) */
-- 
2.20.1


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Re: [PATCH v2 1/2] dmaengine: at_hdmac: Repair bitfield macros for peripheral ID handling

[Tudor Ambarus]

On 5/23/23 18:20, Peter Rosin wrote:
> The MSB part of the peripheral IDs need to go into the ATC_SRC_PER_MSB
> and ATC_DST_PER_MSB fields. Not the LSB part.
> 
> This fixes a severe regression for TSE-850 devices (compatible
> axentia,tse850v3) where output to the audio I2S codec (the main
> purpose of the device) simply do not work.
> 
> Fixes: d8840a7edcf0 ("dmaengine: at_hdmac: Use bitfield access macros")
> Cc: stable@vger.kernel.org
> Signed-off-by: Peter Rosin <peda@axentia.se>

Reviewed-by: Tudor Ambarus <tudor.ambarus@linaro.org>

> ---
>  drivers/dma/at_hdmac.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
> index 8858470246e1..6362013b90df 100644
> --- a/drivers/dma/at_hdmac.c
> +++ b/drivers/dma/at_hdmac.c
> @@ -153,8 +153,6 @@
>  #define ATC_AUTO		BIT(31)		/* Auto multiple buffer tx enable */
>  
>  /* Bitfields in CFG */
> -#define ATC_PER_MSB(h)	((0x30U & (h)) >> 4)	/* Extract most significant bits of a handshaking identifier */
> -
>  #define ATC_SRC_PER		GENMASK(3, 0)	/* Channel src rq associated with periph handshaking ifc h */
>  #define ATC_DST_PER		GENMASK(7, 4)	/* Channel dst rq associated with periph handshaking ifc h */
>  #define ATC_SRC_REP		BIT(8)		/* Source Replay Mod */
> @@ -181,10 +179,15 @@
>  #define ATC_DPIP_HOLE		GENMASK(15, 0)
>  #define ATC_DPIP_BOUNDARY	GENMASK(25, 16)
>  
> -#define ATC_SRC_PER_ID(id)	(FIELD_PREP(ATC_SRC_PER_MSB, (id)) |	\
> -				 FIELD_PREP(ATC_SRC_PER, (id)))
> -#define ATC_DST_PER_ID(id)	(FIELD_PREP(ATC_DST_PER_MSB, (id)) |	\
> -				 FIELD_PREP(ATC_DST_PER, (id)))
> +#define ATC_PER_MSB		GENMASK(5, 4)	/* Extract MSBs of a handshaking identifier */
> +#define ATC_SRC_PER_ID(id)					       \
> +	({ typeof(id) _id = (id);				       \
> +	   FIELD_PREP(ATC_SRC_PER_MSB, FIELD_GET(ATC_PER_MSB, _id)) |  \
> +	   FIELD_PREP(ATC_SRC_PER, _id); })
> +#define ATC_DST_PER_ID(id)					       \
> +	({ typeof(id) _id = (id);				       \
> +	   FIELD_PREP(ATC_DST_PER_MSB, FIELD_GET(ATC_PER_MSB, _id)) |  \
> +	   FIELD_PREP(ATC_DST_PER, _id); })
>  
>  
>  

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Re: [PATCH v2 0/2] dmaengine: at_hdmac: Regression fix and cleanup

[Vinod Koul]

On 23-05-23, 19:19, Peter Rosin wrote:
> Hi!
> 
> I found a regression in DMA handling on one of our SAMA5D3 boards.
> 
> While combing through the regressing commit, a found two unrelated
> strange things. The first is the actually problematic change. The
> second is a number of suspect defines, that I fail to see how they
> can ever do any good.

Applied, thanks

-- 
~Vinod

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