From: "Marek Behún" <kabel@kernel.org>
To: linux-i2c@vger.kernel.org, Wolfram Sang <wsa@kernel.org>,
Gregory CLEMENT <gregory.clement@bootlin.com>
Cc: "Samuel Holland" <samuel@sholland.org>,
"Ondrej Jirman" <megous@megous.com>,
"Marek Behún" <kabel@kernel.org>
Subject: [PATCH] i2c: mv64xxx: Fix random system lock caused by runtime PM
Date: Thu, 8 Apr 2021 04:00:00 +0200 [thread overview]
Message-ID: <20210408020000.21914-1-kabel@kernel.org> (raw)
I noticed a weird bug with this driver on Marvell CN9130 Customer
Reference Board.
Sometime after boot, the system locks with the following message:
[104.071363] i2c i2c-0: mv64xxx: I2C bus locked, block: 1, time_left: 0
The system does not respond afterwards, only warns about RCU stalls.
This first appeared with commit e5c02cf54154 ("i2c: mv64xxx: Add runtime
PM support").
With further experimentation I discovered that adding a delay into
mv64xxx_i2c_hw_init() fixes this issue. This function is called before
every xfer, due to how runtime PM works in this driver. It seems that in
order to work correctly, a delay is needed after the bus is reset in
this function.
Since there already is a known erratum with this controller needing a
delay, I assume that this is just another place this needs to be
applied. Therefore I apply the delay only if errata_delay is true.
Signed-off-by: Marek Behún <kabel@kernel.org>
---
drivers/i2c/busses/i2c-mv64xxx.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
index c590d36b5fd1..5c8e94b6cdb5 100644
--- a/drivers/i2c/busses/i2c-mv64xxx.c
+++ b/drivers/i2c/busses/i2c-mv64xxx.c
@@ -221,6 +221,10 @@ mv64xxx_i2c_hw_init(struct mv64xxx_i2c_data *drv_data)
writel(0, drv_data->reg_base + drv_data->reg_offsets.ext_addr);
writel(MV64XXX_I2C_REG_CONTROL_TWSIEN | MV64XXX_I2C_REG_CONTROL_STOP,
drv_data->reg_base + drv_data->reg_offsets.control);
+
+ if (drv_data->errata_delay)
+ udelay(5);
+
drv_data->state = MV64XXX_I2C_STATE_IDLE;
}
--
2.26.2
next reply other threads:[~2021-04-08 2:00 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-08 2:00 Marek Behún [this message]
2021-04-10 16:47 ` [PATCH] i2c: mv64xxx: Fix random system lock caused by runtime PM Marek Behún
2021-04-13 19:58 ` Wolfram Sang
2021-04-14 13:28 ` Gregory CLEMENT
2021-04-14 14:29 ` Marek Behún
2021-04-14 13:42 ` Samuel Holland
2021-04-15 20:13 ` Wolfram Sang
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