linux-kernel - Re: [PATCH v2 20/91] clk: bcm: rpi: Discover the firmware clocks

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Message-ID: <159056299757.88029.2814367530440231587@swboyd.mtv.corp.google.com>
Date:   Wed, 27 May 2020 00:03:17 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Eric Anholt <eric@...olt.net>, Maxime Ripard <maxime@...no.tech>,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
Cc:     dri-devel@...ts.freedesktop.org,
        linux-rpi-kernel@...ts.infradead.org,
        bcm-kernel-feedback-list@...adcom.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        Tim Gover <tim.gover@...pberrypi.com>,
        Phil Elwell <phil@...pberrypi.com>,
        Maxime Ripard <maxime@...no.tech>,
        Michael Turquette <mturquette@...libre.com>,
        linux-clk@...r.kernel.org
Subject: Re: [PATCH v2 20/91] clk: bcm: rpi: Discover the firmware clocks

Quoting Maxime Ripard (2020-04-24 08:34:01)
> The RaspberryPi4 firmware actually exposes more clocks than are currently
> handled by the driver and we will need to change some of them directly
> based on the pixel rate for the display related clocks, or the load for the
> GPU.
> 
> This rate change can have a number of side-effects, including adjusting the
> various PLL voltages or the PLL parents. The firmware will also update
> those clocks by itself for example if the SoC runs too hot.
> 
> In order to make Linux play as nice as possible with those constraints, it
> makes sense to rely on the firmware clocks as much as possible.
> 
> Fortunately,t he firmware has an interface to discover the clocks it

Fortunately, the

> exposes.
> 
> Let's use it to discover, register the clocks in the clocks framework and
> then expose them through the device tree for consumers to use them.
> 
> Cc: Michael Turquette <mturquette@...libre.com>
> Cc: Stephen Boyd <sboyd@...nel.org>
> Cc: linux-clk@...r.kernel.org
> Signed-off-by: Maxime Ripard <maxime@...no.tech>
> ---

Reviewed-by: Stephen Boyd <sboyd@...nel.org>