[linux-yocto] [PATCH 15/29] spi/pxa2xx: Fix BYT ACPI mode SPI DMA transfer failure at low speeds

[Kamble, Nitin A]

On 4/7/2014 8:18 AM, rebecca.swee.fun.chang at intel.com wrote:
> From: "Chew, Chiau Ee" <chiau.ee.chew at intel.com>
>
> BYT ACPI mode SPI not read/writing correctly at low speeds
> using DMA mode. Fix the issue by changing DMA SRC_MSIZE and
> DEST_MSIZE of SPI FIFO side from 16 to 32.
I think a bit of explanation is needed here, why changing the sizes from 16
to 32 fixes the issue. Also I will correct grammatical errors in the 
commit message.
As these commits logs go in public tree, and stay there forever, it is 
important, to
not leave any grammatical mistakes in the commit logs.

Nitin

> Signed-off-by: Chew, Chiau Ee <chiau.ee.chew at intel.com>
> Signed-off-by: Maurice Petallo <mauricex.r.petallo at intel.com>
> ---
>   drivers/spi/spi-pxa2xx-dma.c |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/spi/spi-pxa2xx-dma.c b/drivers/spi/spi-pxa2xx-dma.c
> index 3c0b551..79515ed 100644
> --- a/drivers/spi/spi-pxa2xx-dma.c
> +++ b/drivers/spi/spi-pxa2xx-dma.c
> @@ -385,7 +385,7 @@ int pxa2xx_spi_set_dma_burst_and_threshold(struct chip_data *chip,
>   	 * otherwise we use the default. Also we use the default FIFO
>   	 * thresholds for now.
>   	 */
> -	*burst_code = chip_info ? chip_info->dma_burst_size : 16;
> +	*burst_code = chip_info ? chip_info->dma_burst_size : 32;
>   	*threshold = SSCR1_RxTresh(RX_THRESH_DFLT)
>   		   | SSCR1_TxTresh(TX_THRESH_DFLT);
>