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Message-Id: <20200319201140.17451-2-digetx@gmail.com>
Date: Thu, 19 Mar 2020 23:11:39 +0300
From: Dmitry Osipenko <digetx@...il.com>
To: Thierry Reding <thierry.reding@...il.com>,
Jonathan Hunter <jonathanh@...dia.com>,
Laxman Dewangan <ldewangan@...dia.com>,
Wolfram Sang <wsa@...-dreams.de>
Cc: linux-i2c@...r.kernel.org, linux-tegra@...r.kernel.org,
Vinod Koul <vkoul@...nel.org>,
Dan Williams <dan.j.williams@...el.com>,
dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v1 1/2] i2c: tegra: Better handle case where CPU0 is busy for a long time
Boot CPU0 always handle I2C interrupt and under some rare circumstances
(like running KASAN + NFS root) it may stuck in uninterruptible state for
a significant time. In this case we will get timeout if I2C transfer is
running on a sibling CPU, despite of IRQ being raised. In order to handle
this rare condition, the IRQ status needs to be checked after completion
timeout.
Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---
drivers/i2c/busses/i2c-tegra.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index cbc2ad49043e..dabb9223990c 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -1034,14 +1034,18 @@ tegra_i2c_wait_completion_timeout(struct tegra_i2c_dev *i2c_dev,
disable_irq(i2c_dev->irq);
/*
- * There is a chance that completion may happen after IRQ
- * synchronization, which is done by disable_irq().
+ * Under some rare circumstances (like running KASAN +
+ * NFS root) CPU, which handles interrupt, may stuck in
+ * uninterruptible state for a significant time. In this
+ * case we will get timeout if I2C transfer is running on
+ * a sibling CPU, despite of IRQ being raised.
+ *
+ * In order to handle this rare condition, the IRQ status
+ * needs to be checked after timeout.
*/
- if (ret == 0 && completion_done(complete)) {
- dev_warn(i2c_dev->dev,
- "completion done after timeout\n");
- ret = 1;
- }
+ if (ret == 0)
+ ret = tegra_i2c_poll_completion_timeout(i2c_dev,
+ complete, 0);
}
return ret;
--
2.25.1
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