Re: [PATCH AUTOSEL 5.6 30/38] i2c: tegra: Better handle case where CPU0 is busy for a long time

Thierry Reding
2020-04-27T07:22:39Z

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On Fri, Apr 24, 2020 at 08:22:28AM -0400, Sasha Levin wrote:
> From: Dmitry Osipenko <digetx@gmail.com>
>
> [ Upstream commit a900aeac253729411cf33c6cb598c152e9e4137f ]
>
> 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>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> drivers/i2c/busses/i2c-tegra.c | 27 +++++++++++++++------------
> 1 file changed, 15 insertions(+), 12 deletions(-)

Hi Sasha,

can you drop this from the v5.6 stable queue please? Jon discovered that
this patch introduces a regression in v5.7, and since we don't have a
good understanding of why this is breaking things I think it'd be best
if we reverted it for v5.7 until we come up with a good fix.

I think the same applies for the other i2c/tegra patch that's 31/38 of
this series.

Thanks,
Thierry

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