Re: [PATCH 3.4 115/176] spi: dw: Fix detecting FIFO depth

[Axel Lin]

2015-04-09 16:46 GMT+08:00  <lizf@xxxxxxxxxx>:
> From: Axel Lin <axel.lin@xxxxxxxxxx>
>
> 3.4.107-rc1 review patch.  If anyone has any objections, please let me know.
>
> ------------------
>
>
> commit d297933cc7fcfbaaf2d37570baac73287bf0357d upstream.
>
> Current code tries to find the highest valid fifo depth by checking the value
> it wrote to DW_SPI_TXFLTR. There are a few problems in current code:
> 1) There is an off-by-one in dws->fifo_len setting because it assumes the latest
>    register write fails so the latest valid value should be fifo - 1.
> 2) We know the depth could be from 2 to 256 from HW spec, so it is not necessary
>    to test fifo == 257. In the case fifo is 257, it means the latest valid
>    setting is fifo = 256. So after the for loop iteration, we should check
>    fifo == 2 case instead of fifo == 257 if detecting the FIFO depth fails.
> This patch fixes above issues.
>
> Signed-off-by: Axel Lin <axel.lin@xxxxxxxxxx>
> Reviewed-and-tested-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
> [lizf: Backported to 3.4: adjust context]
> Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>

Hi,
This patch needs below fix:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/spi/spi-dw.c?id=9d239d353c319f9ff884c287ce47feb7cdf60ddc

Thanks,
Axel
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