[PATCH 2/2] ARM: sunxi: spi: add notice about SPI FIFO limit.

Maxime Ripard
2016-03-06T18:12:48Z

Hi,

On Fri, Feb 26, 2016 at 07:56:57AM +0200, Priit Laes wrote:
> From: Michal Suchanek <hramrach@gmail.com>
>
> When testing SPI without DMA I noticed that filling the FIFO on the
> spi controller causes timeout. This should never happen with DMA support
> so just adding a comment.
>
> Signed-off-by: Michal Suchanek <hramrach@gmail.com>
> ---
> drivers/spi/spi-sun4i.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/spi/spi-sun4i.c b/drivers/spi/spi-sun4i.c
> index 78141a6..b750664 100644
> --- a/drivers/spi/spi-sun4i.c
> +++ b/drivers/spi/spi-sun4i.c
> @@ -333,7 +333,9 @@ static int sun4i_spi_transfer_one(struct spi_master *master,
> sun4i_spi_write(sspi, SUN4I_DMA_CTL_REG, 0);
>
> /* Fill the TX FIFO */
> - sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH);
> + /* Filling the fifo fully causes timeout for some reason - at least on spi2 on a10s */
> + /* The can_dma check is txlen >= SUN4I_FIFO_DEPTH so with DMA this should never happen anyway. */
> + sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH - 1);

Please wrap the lines at 80 chars and use the proper multiline comment
style.

Thanks!
Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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