spi: dw: use "smp_mb()" to avoid sending spi data error

[ Upstream commit bfda044533b213985bc62bd7ca96f2b984d21b80 ]

Because of out-of-order execution about some CPU architecture,
In this debug stage we find Completing spi interrupt enable ->
prodrucing TXEI interrupt -> running "interrupt_transfer" function
will prior to set "dw->rx and dws->rx_end" data, so this patch add
memory barrier to enable dw->rx and dw->rx_end to be visible and
solve to send SPI data error.
eg:
it will fix to this following low possibility error in testing environment
which using SPI control to connect TPM Modules

kernel: tpm tpm0: Operation Timed out
kernel: tpm tpm0: tpm_relinquish_locality: : error -1

Signed-off-by: fengsheng <fengsheng5@huawei.com>
Signed-off-by: Xinwei Kong <kong.kongxinwei@hisilicon.com>
Link: https://lore.kernel.org/r/1578019930-55858-1-git-send-email-kong.kongxinwei@hisilicon.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index 4edd38d03b939bcb186230ff14227f23445ca60b..5688591e9cd39372a7a8c976e1b4ed7080e43f43 100644 (file)
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -306,6 +306,9 @@ static int dw_spi_transfer_one(struct spi_master *master,
        dws->len = transfer->len;
        spin_unlock_irqrestore(&dws->buf_lock, flags);
 
+       /* Ensure dw->rx and dw->rx_end are visible */
+       smp_mb();
+
        spi_enable_chip(dws, 0);
 
        /* Handle per transfer options for bpw and speed */