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spi: sun4i: fix FIFO limit 

When testing SPI without DMA I noticed that filling the FIFO on the
spi controller causes timeout.

Always leave room for one byte in the FIFO.

Signed-off-by: Michal Suchanek <hramrach@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
This commit is contained in:
Michal Suchanek 2016-06-13 17:46:49 +00:00 committed by Mark Brown
parent 1a695a905c
commit 6d9fe44bd7
1 changed files with 10 additions and 3 deletions
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13
drivers/spi/spi-sun4i.c
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@ -179,7 +179,10 @@ static int sun4i_spi_transfer_one(struct spi_master *master,
/* We don't support transfer larger than the FIFO */
if (tfr->len > SUN4I_FIFO_DEPTH)
return -EINVAL;
return -EMSGSIZE;
if (tfr->tx_buf && tfr->len >= SUN4I_FIFO_DEPTH)
return -EMSGSIZE;
reinit_completion(&sspi->done);
sspi->tx_buf = tfr->tx_buf;
@ -269,8 +272,12 @@ static int sun4i_spi_transfer_one(struct spi_master *master,
sun4i_spi_write(sspi, SUN4I_BURST_CNT_REG, SUN4I_BURST_CNT(tfr->len));
sun4i_spi_write(sspi, SUN4I_XMIT_CNT_REG, SUN4I_XMIT_CNT(tx_len));
/* Fill the TX FIFO */
sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH);
/*
* Fill the TX FIFO
* Filling the FIFO fully causes timeout for some reason
* at least on spi2 on A10s
*/
sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH - 1);
/* Enable the interrupts */
sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, SUN4I_INT_CTL_TC);