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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, Ondrej Jirman <megous@megous.com>,
	John Keeping <john@metanate.com>, Wolfram Sang <wsa@kernel.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 05/18] i2c: rk3x: Handle a spurious start completion interrupt flag
Date: Wed, 15 Dec 2021 18:21:26 +0100	[thread overview]
Message-ID: <20211215172022.997127046@linuxfoundation.org> (raw)
In-Reply-To: <20211215172022.795825673@linuxfoundation.org>

From: Ondrej Jirman <megous@megous.com>

[ Upstream commit 02fe0fbd8a21e183687925c3a266ae27dda9840f ]

In a typical read transfer, start completion flag is being set after
read finishes (notice ipd bit 4 being set):

trasnfer poll=0
i2c start
rk3x-i2c fdd40000.i2c: IRQ: state 1, ipd: 10
i2c read
rk3x-i2c fdd40000.i2c: IRQ: state 2, ipd: 1b
i2c stop
rk3x-i2c fdd40000.i2c: IRQ: state 4, ipd: 33

This causes I2C transfer being aborted in polled mode from a stop completion
handler:

trasnfer poll=1
i2c start
rk3x-i2c fdd40000.i2c: IRQ: state 1, ipd: 10
i2c read
rk3x-i2c fdd40000.i2c: IRQ: state 2, ipd: 0
rk3x-i2c fdd40000.i2c: IRQ: state 2, ipd: 1b
i2c stop
rk3x-i2c fdd40000.i2c: IRQ: state 4, ipd: 13
i2c stop
rk3x-i2c fdd40000.i2c: unexpected irq in STOP: 0x10

Clearing the START flag after read fixes the issue without any obvious
side effects.

This issue was dicovered on RK3566 when adding support for powering
off the RK817 PMIC.

Signed-off-by: Ondrej Jirman <megous@megous.com>
Reviewed-by: John Keeping <john@metanate.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/i2c/busses/i2c-rk3x.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c
index 1a33007b03e9e..1107a5e7229e4 100644
--- a/drivers/i2c/busses/i2c-rk3x.c
+++ b/drivers/i2c/busses/i2c-rk3x.c
@@ -422,8 +422,8 @@ static void rk3x_i2c_handle_read(struct rk3x_i2c *i2c, unsigned int ipd)
 	if (!(ipd & REG_INT_MBRF))
 		return;
 
-	/* ack interrupt */
-	i2c_writel(i2c, REG_INT_MBRF, REG_IPD);
+	/* ack interrupt (read also produces a spurious START flag, clear it too) */
+	i2c_writel(i2c, REG_INT_MBRF | REG_INT_START, REG_IPD);
 
 	/* Can only handle a maximum of 32 bytes at a time */
 	if (len > 32)
-- 
2.33.0




  parent reply	other threads:[~2021-12-15 17:27 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-15 17:21 [PATCH 5.4 00/18] 5.4.166-rc1 review Greg Kroah-Hartman
2021-12-15 17:21 ` [PATCH 5.4 01/18] nfc: fix segfault in nfc_genl_dump_devices_done Greg Kroah-Hartman
2021-12-15 17:21 ` [PATCH 5.4 02/18] drm/msm/dsi: set default num_data_lanes Greg Kroah-Hartman
2021-12-15 17:21 ` [PATCH 5.4 03/18] net/mlx4_en: Update reported link modes for 1/10G Greg Kroah-Hartman
2021-12-15 17:21 ` [PATCH 5.4 04/18] parisc/agp: Annotate parisc agp init functions with __init Greg Kroah-Hartman
2021-12-15 17:21 ` Greg Kroah-Hartman [this message]
2021-12-15 17:21 ` [PATCH 5.4 06/18] net: netlink: af_netlink: Prevent empty skb by adding a check on len Greg Kroah-Hartman
2021-12-15 17:21 ` [PATCH 5.4 07/18] drm/amd/display: Fix for the no Audio bug with Tiled Displays Greg Kroah-Hartman
2021-12-15 17:21 ` [PATCH 5.4 08/18] drm/amd/display: add connector type check for CRC source set Greg Kroah-Hartman
2021-12-15 17:21 ` [PATCH 5.4 09/18] tracing: Fix a kmemleak false positive in tracing_map Greg Kroah-Hartman
2021-12-15 17:21 ` [PATCH 5.4 10/18] KVM: x86: Ignore sparse banks size for an "all CPUs", non-sparse IPI req Greg Kroah-Hartman
2021-12-15 17:21 ` [PATCH 5.4 11/18] selinux: fix race condition when computing ocontext SIDs Greg Kroah-Hartman
2021-12-15 17:21 ` [PATCH 5.4 12/18] bpf: Fix integer overflow in argument calculation for bpf_map_area_alloc Greg Kroah-Hartman
2021-12-15 17:21 ` [PATCH 5.4 13/18] hwmon: (dell-smm) Fix warning on /proc/i8k creation error Greg Kroah-Hartman
2021-12-15 17:21 ` [PATCH 5.4 14/18] memblock: free_unused_memmap: use pageblock units instead of MAX_ORDER Greg Kroah-Hartman
2021-12-15 17:21 ` [PATCH 5.4 15/18] memblock: align freed memory map on pageblock boundaries with SPARSEMEM Greg Kroah-Hartman
2021-12-15 17:21 ` [PATCH 5.4 16/18] memblock: ensure there is no overflow in memblock_overlaps_region() Greg Kroah-Hartman
2021-12-15 17:21 ` [PATCH 5.4 17/18] arm: extend pfn_valid to take into account freed memory map alignment Greg Kroah-Hartman
2021-12-15 17:21 ` [PATCH 5.4 18/18] arm: ioremap: dont abuse pfn_valid() to check if pfn is in RAM Greg Kroah-Hartman
2021-12-15 20:00 ` [PATCH 5.4 00/18] 5.4.166-rc1 review Jon Hunter
2021-12-15 21:52 ` Shuah Khan
2021-12-15 22:47 ` Florian Fainelli
2021-12-16 11:47 ` Naresh Kamboju
2021-12-16 18:07 ` Guenter Roeck
2021-12-17  0:53 ` Samuel Zou

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