linux-kernel - Re: [PATCH v4 2/5] soc/tegra: pmc: Fix completion of power-gate toggling

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Message-ID: <YFye9WEL489M1KOk@orome.fritz.box>
Date:   Thu, 25 Mar 2021 15:32:21 +0100
From:   Thierry Reding <thierry.reding@...il.com>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Jonathan Hunter <jonathanh@...dia.com>,
        Peter Geis <pgwipeout@...il.com>,
        Matt Merhar <mattmerhar@...tonmail.com>,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/5] soc/tegra: pmc: Fix completion of power-gate
 toggling

On Tue, Mar 02, 2021 at 03:24:59PM +0300, Dmitry Osipenko wrote:
> The SW-initiated power gate toggling is dropped by PMC if there is
> contention with a HW-initiated toggling, i.e. when one of CPU cores is
> gated by cpuidle driver. Software should retry the toggling after 10
> microseconds on Tegra20/30 SoCs, hence add the retrying. On Tegra114+ the
> toggling method was changed in hardware, the TOGGLE_START bit indicates
> whether PMC is busy or could accept the command to toggle, hence handle
> that bit properly.
> 
> The problem pops up after enabling dynamic power gating of 3d hardware,
> where 3d power domain fails to turn on/off "randomly".
> 
> The programming sequence and quirks are documented in TRMs, but PMC
> driver obliviously re-used the Tegra20 logic for Tegra30+, which strikes
> back now. The 10 microseconds and other timeouts aren't documented in TRM,
> they are taken from downstream kernel.
> 
> Link: https://nv-tegra.nvidia.com/gitweb/?p=linux-2.6.git;a=commit;h=311dd1c318b70e93bcefec15456a10ff2b9eb0ff
> Link: https://nv-tegra.nvidia.com/gitweb/?p=linux-3.10.git;a=commit;h=7f36693c47cb23730a6b2822e0975be65fb0c51d
> Tested-by: Peter Geis <pgwipeout@...il.com> # Ouya T30
> Tested-by: Nicolas Chauvet <kwizart@...il.com> # PAZ00 T20 and TK1 T124
> Tested-by: Matt Merhar <mattmerhar@...tonmail.com> # Ouya T30
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/soc/tegra/pmc.c | 70 ++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 65 insertions(+), 5 deletions(-)

Applied, thanks.

Thierry

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