From mboxrd@z Thu Jan 1 00:00:00 1970 From: maxime.ripard@free-electrons.com (Maxime Ripard) Date: Sun, 6 Mar 2016 19:12:48 +0100 Subject: [PATCH 2/2] ARM: sunxi: spi: add notice about SPI FIFO limit. In-Reply-To: <1456466217-6793-3-git-send-email-plaes@plaes.org> References: <1456466217-6793-1-git-send-email-plaes@plaes.org> <1456466217-6793-3-git-send-email-plaes@plaes.org> Message-ID: <20160306181248.GV8418@lukather> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, On Fri, Feb 26, 2016 at 07:56:57AM +0200, Priit Laes wrote: > From: Michal Suchanek > > 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 > --- > 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 -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 819 bytes Desc: Digital signature URL: