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spi: lantiq: fix: Rx overflow error in full duplex mode 

[ Upstream commit 661ccf2b3f ]

In full duplex mode, rx overflow error is observed. To overcome the error,
wait until the complete data got received and proceed further.

Fixes: 17f84b793c ("spi: lantiq-ssc: add support for Lantiq SSC SPI controller")
Signed-off-by: Dilip Kota <eswara.kota@linux.intel.com>
Link: https://lore.kernel.org/r/efb650b0faa49a00788c4e0ca8ef7196bdba851d.1594957019.git.eswara.kota@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Dilip Kota 2020-07-17 14:27:50 +08:00 committed by Greg Kroah-Hartman
parent e22730350d
commit b1fe27d227
1 changed files with 10 additions and 0 deletions
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10
drivers/spi/spi-lantiq-ssc.c
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@ -184,6 +184,7 @@ struct lantiq_ssc_spi {
unsigned int tx_fifo_size;
unsigned int rx_fifo_size;
unsigned int base_cs;
unsigned int fdx_tx_level;
};
static u32 lantiq_ssc_readl(const struct lantiq_ssc_spi *spi, u32 reg)
@ -481,6 +482,7 @@ static void tx_fifo_write(struct lantiq_ssc_spi *spi)
u32 data;
unsigned int tx_free = tx_fifo_free(spi);
spi->fdx_tx_level = 0;
while (spi->tx_todo && tx_free) {
switch (spi->bits_per_word) {
case 2 ... 8:
@ -509,6 +511,7 @@ static void tx_fifo_write(struct lantiq_ssc_spi *spi)
lantiq_ssc_writel(spi, data, LTQ_SPI_TB);
tx_free--;
spi->fdx_tx_level++;
}
}
@ -520,6 +523,13 @@ static void rx_fifo_read_full_duplex(struct lantiq_ssc_spi *spi)
u32 data;
unsigned int rx_fill = rx_fifo_level(spi);
/*
* Wait until all expected data to be shifted in.
* Otherwise, rx overrun may occur.
*/
while (rx_fill != spi->fdx_tx_level)
rx_fill = rx_fifo_level(spi);
while (rx_fill) {
data = lantiq_ssc_readl(spi, LTQ_SPI_RB);