| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 43/68] spi: sun4i: fix FIFO limit | Date | Mon, 8 Aug 2016 21:11:18 +0200 |
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4.4-stable review patch. If anyone has any objections, please let me know.
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From: Michal Suchanek <hramrach@gmail.com>
commit 6d9fe44bd73d567d04d3a68a2d2fa521ab9532f2 upstream.
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/spi/spi-sun4i.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)
--- a/drivers/spi/spi-sun4i.c +++ b/drivers/spi/spi-sun4i.c @@ -177,7 +177,10 @@ static int sun4i_spi_transfer_one(struct /* 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; @@ -270,8 +273,12 @@ static int sun4i_spi_transfer_one(struct 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);
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