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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@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Dmitry Osipenko 2020-03-24 22:12:16 +03:00 committed by Wolfram Sang
parent 3c1d1613be
commit a900aeac25
1 changed files with 15 additions and 12 deletions
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21
drivers/i2c/busses/i2c-tegra.c
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@ -996,7 +996,7 @@ tegra_i2c_poll_completion_timeout(struct tegra_i2c_dev *i2c_dev,
do {
u32 status = i2c_readl(i2c_dev, I2C_INT_STATUS);
if (status) {
if (status)
tegra_i2c_isr(i2c_dev->irq, i2c_dev);
if (completion_done(complete)) {
@ -1004,7 +1004,6 @@ tegra_i2c_poll_completion_timeout(struct tegra_i2c_dev *i2c_dev,
return msecs_to_jiffies(delta) ?: 1;
}
}
ktime = ktime_get();
@ -1030,14 +1029,18 @@ 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;