[PATCH 0/3] Add dma_alignment field to spi_master

[PATCH 0/3] Add dma_alignment field to spi_master

[Mike Rapoport]

Some SPI controllers have restrictions on DMAable buffers alignemt.
Currently if the buffer supplied by protocol driver is not properly
aligned, the controller silently performs transfer in PIO mode.
Addition of dma_alignment field to spi_master allows protocol drivers to
perform proper alignment.

Mike Rapoport (3):
  SPI: add dma_alignment field to spi_master
  pxa2xx_spi: set spi_master.dma_alignment = 8
  spi_imx: set spi_master.dma_alignment = 4

 drivers/spi/pxa2xx_spi.c |    2 ++
 drivers/spi/spi_imx.c    |    2 ++
 include/linux/spi/spi.h  |    6 ++++++
 3 files changed, 10 insertions(+), 0 deletions(-)


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[PATCH 1/3] SPI: add dma_alignment field to spi_master

[Mike Rapoport]

Some SPI controllers have restrictions on DMAable buffers alignemt.
Currently if the buffer supplied by protocol driver is not properly
aligned, the controller silently performs transfer in PIO mode.
Addition of dma_alignment field to spi_master allows protocol drivers to
perform proper alignment.

Signed-off-by: Mike Rapoport <mike-UTxiZqZC01RS1MOuV/RT9w@public.gmane.org>
---
 include/linux/spi/spi.h |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 68bb1c5..2cc43fa 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -204,6 +204,7 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
  *	SPI slaves, and are numbered from zero to num_chipselects.
  *	each slave has a chipselect signal, but it's common that not
  *	every chipselect is connected to a slave.
+ * @dma_alignment: SPI controller constraint on DMA buffers alignment.
  * @setup: updates the device mode and clocking records used by a
  *	device's SPI controller; protocol code may call this.  This
  *	must fail if an unrecognized or unsupported mode is requested.
@@ -239,6 +240,11 @@ struct spi_master {
 	 */
 	u16			num_chipselect;
 
+	/* some SPI controllers pose alignment requirements on DMAable
+	 * buffers; let protocol drivers know about these requirements.
+	 */
+	u16			dma_alignment;
+
 	/* setup mode and clock, etc (spi driver may call many times) */
 	int			(*setup)(struct spi_device *spi);
 
-- 
1.5.6.4


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[PATCH 2/3] pxa2xx_spi: set spi_master.dma_alignment = 8

[Mike Rapoport]

Signed-off-by: Mike Rapoport <mike-UTxiZqZC01RS1MOuV/RT9w@public.gmane.org>
---
 drivers/spi/pxa2xx_spi.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/spi/pxa2xx_spi.c b/drivers/spi/pxa2xx_spi.c
index d0fc4ca..e38f6e0 100644
--- a/drivers/spi/pxa2xx_spi.c
+++ b/drivers/spi/pxa2xx_spi.c
@@ -55,6 +55,7 @@ MODULE_ALIAS("platform:pxa2xx-spi");
 #define RESET_DMA_CHANNEL	(DCSR_NODESC | DMA_INT_MASK)
 #define IS_DMA_ALIGNED(x)	((((u32)(x)) & 0x07) == 0)
 #define MAX_DMA_LEN		8191
+#define DMA_ALIGNMENT		8
 
 /*
  * for testing SSCR1 changes that require SSP restart, basically
@@ -1440,6 +1441,7 @@ static int __init pxa2xx_spi_probe(struct platform_device *pdev)
 
 	master->bus_num = pdev->id;
 	master->num_chipselect = platform_info->num_chipselect;
+	master->dma_alignment = DMA_ALIGNMENT;
 	master->cleanup = cleanup;
 	master->setup = setup;
 	master->transfer = transfer;
-- 
1.5.6.4


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[PATCH 3/3] spi_imx: set spi_master.dma_alignment = 4

[Mike Rapoport]

Signed-off-by: Mike Rapoport <mike-UTxiZqZC01RS1MOuV/RT9w@public.gmane.org>
---
 drivers/spi/spi_imx.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/spi/spi_imx.c b/drivers/spi/spi_imx.c
index 269a55e..b36b5a1 100644
--- a/drivers/spi/spi_imx.c
+++ b/drivers/spi/spi_imx.c
@@ -186,6 +186,7 @@
 #define QUEUE_STOPPED			(1)
 
 #define IS_DMA_ALIGNED(x) 		(((u32)(x) & 0x03) == 0)
+#define DMA_ALIGNMENT			4
 /*-------------------------------------------------------------------------*/
 
 
@@ -1481,6 +1482,7 @@ static int __init spi_imx_probe(struct platform_device *pdev)
 
 	master->bus_num = pdev->id;
 	master->num_chipselect = platform_info->num_chipselect;
+	master->dma_alignment = DMA_ALIGNMENT;
 	master->cleanup = cleanup;
 	master->setup = setup;
 	master->transfer = transfer;
-- 
1.5.6.4


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Re: [PATCH 0/3] Add dma_alignment field to spi_master

[Mike Rapoport]

David,
Any comments?

Mike Rapoport wrote:
> Some SPI controllers have restrictions on DMAable buffers alignemt.
> Currently if the buffer supplied by protocol driver is not properly
> aligned, the controller silently performs transfer in PIO mode.
> Addition of dma_alignment field to spi_master allows protocol drivers to
> perform proper alignment.
> 
> Mike Rapoport (3):
>   SPI: add dma_alignment field to spi_master
>   pxa2xx_spi: set spi_master.dma_alignment = 8
>   spi_imx: set spi_master.dma_alignment = 4
> 
>  drivers/spi/pxa2xx_spi.c |    2 ++
>  drivers/spi/spi_imx.c    |    2 ++
>  include/linux/spi/spi.h  |    6 ++++++
>  3 files changed, 10 insertions(+), 0 deletions(-)
> 

-- 
Sincerely yours,
Mike.


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