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authorMartin Sperl <kernel@martin.sperl.org>2019-03-30 09:31:00 +0000
committerMark Brown <broonie@kernel.org>2019-04-03 11:31:11 +0700
commit73b114ee7db1750c0b535199fae383b109bd61d0 (patch)
tree01076bca50c2a604f8a21ea5cb99d5ee90e556aa /drivers/spi/spi-bcm2835aux.c
parentc7de8500fd8ecbb544846dd5f11dca578c3777e1 (diff)
spi: bcm2835aux: fix corruptions for longer spi transfers
On long running tests with a mcp2517fd can controller it showed that on rare occations the data read shows corruptions for longer spi transfers. Example of a 22 byte transfer: expected (as captured on logic analyzer): FF FF 78 00 00 00 08 06 00 00 91 20 77 56 84 85 86 87 88 89 8a 8b read by the driver: FF FF 78 00 00 00 08 06 00 00 91 20 77 56 84 88 89 8a 00 00 8b 9b To fix this use BCM2835_AUX_SPI_STAT_RX_LVL to determine when we may read data from the fifo reliably without any corruption. Surprisingly the only values ever empirically read in BCM2835_AUX_SPI_STAT_RX_LVL are 0x00, 0x10, 0x20 and 0x30. So whenever the mask is not 0 we can read from the fifo in a safe manner. The patch has now been tested intensively and we are no longer able to reproduce the "RX" issue any longer. Fixes: 1ea29b39f4c812ec ("spi: bcm2835aux: add bcm2835 auxiliary spi device...") Reported-by: Hubert Denkmair <h.denkmair@intence.de> Signed-off-by: Martin Sperl <kernel@martin.sperl.org> Acked-by: Stefan Wahren <stefan.wahren@i2se.com> Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'drivers/spi/spi-bcm2835aux.c')
-rw-r--r--drivers/spi/spi-bcm2835aux.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c
index 0838dbda57c7..d9e62f717a45 100644
--- a/drivers/spi/spi-bcm2835aux.c
+++ b/drivers/spi/spi-bcm2835aux.c
@@ -180,12 +180,12 @@ static void bcm2835aux_spi_reset_hw(struct bcm2835aux_spi *bs)
static void bcm2835aux_spi_transfer_helper(struct bcm2835aux_spi *bs)
{
+ u32 stat = bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT);
+
/* check if we have data to read */
- while (bs->rx_len &&
- (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) &
- BCM2835_AUX_SPI_STAT_RX_EMPTY))) {
+ for (; bs->rx_len && (stat & BCM2835_AUX_SPI_STAT_RX_LVL);
+ stat = bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT))
bcm2835aux_rd_fifo(bs);
- }
/* check if we have data to write */
while (bs->tx_len &&