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[4.4,07/36] spi: dw: use "smp_mb()" to avoid sending spi data error

Message ID 20200609173933.708823642@linuxfoundation.org
State Superseded
Headers show
Series None | expand

Commit Message

Greg KH June 9, 2020, 5:44 p.m. UTC 
From: Xinwei Kong <kong.kongxinwei@hisilicon.com>


[ 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>

---
 drivers/spi/spi-dw.c | 3 +++
 1 file changed, 3 insertions(+)

-- 
2.25.1
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Patch

diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index 4edd38d03b93..5688591e9cd3 100644
--- 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 */