linux-kernel - Re: [PATCH] soc/tegra: pmc: Fix "scheduling while atomic"

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Date:	Thu, 5 May 2016 17:24:26 +0300
From:	Dmitry Osipenko <digetx@...il.com>
To:	Jon Hunter <jonathanh@...dia.com>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Alexandre Courbot <gnurou@...il.com>,
	Peter De Schrijver <pdeschrijver@...dia.com>,
	Prashant Gaikwad <pgaikwad@...dia.com>
Cc:	linux-clk@...r.kernel.org, linux-tegra@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] soc/tegra: pmc: Fix "scheduling while atomic"

Hello, Jon!

On 05.05.2016 16:17, Jon Hunter wrote:
>
> Thanks for the report. I have been unable to reproduce this, but then I
> don't see my tegra20 entering LP2 during cpuidle. I did force my tegra20
> into LP2 during suspend which will exercise the same code but I did not
> trigger this either. However, from looking at the code it does appear
> that we could hit this.
>

As I wrote before, it's quite difficult to reproduce.

>
> Ideally, it would be great if we did not need to add another custom API
> for this, but I did not find anything in the CCF that would allow us to
> avoid but that was only a quick look. However, we could ask the CCF folks.
>

Yes, CCF doesn't expose locked API. Code should be designed to avoid it.

> What I plan to do next is to understand if the pclk is likely to change.
> I know that it comes from one of the plls but I am not sure if we ever
> change the rate. If not we may be able to move this to probe time and
> avoid this.
>

That's reasonable, I'd also take a look at it. Thanks for the comment!

-- 
Dmitry