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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Hubert Denkmair <h.denkmair@intence.de>,
	Martin Sperl <kernel@martin.sperl.org>,
	Stefan Wahren <stefan.wahren@i2se.com>,
	Mark Brown <broonie@kernel.org>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 21/26] spi: bcm2835aux: fix corruptions for longer spi transfers
Date: Sun,  8 Sep 2019 13:42:00 +0100	[thread overview]
Message-ID: <20190908121110.075802835@linuxfoundation.org> (raw)
In-Reply-To: <20190908121057.216802689@linuxfoundation.org>

[ Upstream commit 73b114ee7db1750c0b535199fae383b109bd61d0 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/spi/spi-bcm2835aux.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c
index 4454d9c6a3dd4..5c89bbb05441b 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 &&
-- 
2.20.1




  parent reply	other threads:[~2019-09-08 13:00 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-08 12:41 [PATCH 4.9 00/26] 4.9.192-stable review Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 01/26] net: tundra: tsi108: use spin_lock_irqsave instead of spin_lock_irq in IRQ context Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 02/26] net: tc35815: Explicitly check NET_IP_ALIGN is not zero in tc35815_rx Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 03/26] Bluetooth: btqca: Add a short delay before downloading the NVM Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 04/26] ibmveth: Convert multicast list size for little-endian system Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 05/26] gpio: Fix build error of function redefinition Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 06/26] cxgb4: fix a memory leak bug Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 07/26] net: myri10ge: fix memory leaks Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 08/26] cx82310_eth: fix a memory leak bug Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 09/26] net: kalmia: fix memory leaks Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 10/26] wimax/i2400m: fix a memory leak bug Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 11/26] ravb: Fix use-after-free ravb_tstamp_skb Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 12/26] Tools: hv: kvp: eliminate may be used uninitialized warning Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 13/26] IB/mlx4: Fix memory leaks Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 14/26] ceph: fix buffer free while holding i_ceph_lock in __ceph_setxattr() Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 15/26] ceph: fix buffer free while holding i_ceph_lock in fill_inode() Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 16/26] KVM: arm/arm64: Only skip MMIO insn once Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 17/26] libceph: allow ceph_buffer_put() to receive a NULL ceph_buffer Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 18/26] spi: bcm2835aux: ensure interrupts are enabled for shared handler Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 19/26] spi: bcm2835aux: unifying code between polling and interrupt driven code Greg Kroah-Hartman
2019-09-08 12:41 ` [PATCH 4.9 20/26] spi: bcm2835aux: remove dangerous uncontrolled read of fifo Greg Kroah-Hartman
2019-09-08 12:42 ` Greg Kroah-Hartman [this message]
2019-09-08 12:42 ` [PATCH 4.9 22/26] Revert "x86/apic: Include the LDR when clearing out APIC registers" Greg Kroah-Hartman
2019-09-08 12:42 ` [PATCH 4.9 23/26] net: fix skb use after free in netpoll Greg Kroah-Hartman
2019-09-08 12:42 ` [PATCH 4.9 24/26] net: stmmac: dwmac-rk: Dont fail if phy regulator is absent Greg Kroah-Hartman
2019-09-08 12:42 ` [PATCH 4.9 25/26] tcp: inherit timestamp on mtu probe Greg Kroah-Hartman
2019-09-08 12:42 ` [PATCH 4.9 26/26] mld: fix memory leak in mld_del_delrec() Greg Kroah-Hartman
2019-09-08 16:38 ` [PATCH 4.9 00/26] 4.9.192-stable review kernelci.org bot
2019-09-09  1:33 ` Naresh Kamboju
2019-09-09 14:49 ` Bharath Vedartham
2019-09-09 19:43 ` Guenter Roeck
2019-09-10  9:19 ` Jon Hunter

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