linux-kernel - Re: [Freedreno] [PATCH 1/5] clk: inherit clocks enabled by bootloader

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Message-ID: <CAOCk7Np7jjdzbhX2qUf4h-JyLrqSwthX+=7Hd3vQETBtQDp9DQ@mail.gmail.com>
Date:   Mon, 1 Jul 2019 12:02:52 -0600
From:   Jeffrey Hugo <jeffrey.l.hugo@...il.com>
To:     Rob Clark <robdclark@...il.com>
Cc:     "open list:DRM PANEL DRIVERS" <dri-devel@...ts.freedesktop.org>,
        MSM <linux-arm-msm@...r.kernel.org>,
        Rob Clark <robdclark@...omium.org>,
        aarch64-laptops@...ts.linaro.org, linux-pm@...r.kernel.org,
        Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        lkml <linux-kernel@...r.kernel.org>,
        Andy Gross <agross@...nel.org>,
        freedreno <freedreno@...ts.freedesktop.org>,
        linux-clk@...r.kernel.org
Subject: Re: [Freedreno] [PATCH 1/5] clk: inherit clocks enabled by bootloader

On Sun, Jun 30, 2019 at 9:02 AM Rob Clark <robdclark@...il.com> wrote:
>
> From: Rob Clark <robdclark@...omium.org>
>
> The goal here is to support inheriting a display setup by bootloader,
> although there may also be some non-display related use-cases.
>
> Rough idea is to add a flag for clks and power domains that might
> already be enabled when kernel starts, and which should not be
> disabled at late_initcall if the kernel thinks they are "unused".
>
> If bootloader is enabling display, and kernel is using efifb before
> real display driver is loaded (potentially from kernel module after
> userspace starts, in a typical distro kernel), we don't want to kill
> the clocks and power domains that are used by the display before
> userspace starts.
>
> Signed-off-by: Rob Clark <robdclark@...omium.org>

Seems sane to me.  I'm curious what Stephen Boyd thinks.
I'll try to give it a spin on one of the 835 laptops.

Reviewed-by: Jeffrey Hugo <jeffrey.l.hugo@...il.com>