* Re: [PATCH] spi/pxa2xx: change default supported DMA burst size to 1
[not found] <1401990309-12492-1-git-send-email-chiau.ee.chew@intel.com>
@ 2014-06-05 9:46 ` Mika Westerberg
0 siblings, 0 replies; only message in thread
From: Mika Westerberg @ 2014-06-05 9:46 UTC (permalink / raw)
To: Chew Chiau Ee
Cc: Mark Brown, Eric Miao, Russell King, Haojian Zhuang,
linux-arm-kernel, linux-spi, linux-kernel
On Fri, Jun 06, 2014 at 01:45:09AM +0800, Chew Chiau Ee wrote:
> From: Chew, Chiau Ee <chiau.ee.chew@intel.com>
>
> This is to fix the SPI DMA transfer failure for speed less than 1M.
> If using current DMA burst size setting (16), the Rx data bytes are
> invalid due to each data byte is multiplied according to the burst
> size setting.
>
> Let's said supposedly we shall receive the following 18 bytes of data:
> 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18
> Instead, the data bytes received consist of "16 bytes of '01' +
> 2 bytes of '02'" :
> 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 02 02
>
> Signed-off-by: Chew, Chiau Ee <chiau.ee.chew@intel.com>
> Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Works for me (and individual chips can tune this by passing custom
dma_burst_size if needed).
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
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