linux-kernel - Re: [PATCH v5 00/10] clk: implement clock rate protection mechanism

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Date:   Wed, 20 Dec 2017 18:45:08 +0100
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>
Cc:     linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        Russell King <linux@...linux.org.uk>,
        Linus Walleij <linus.walleij@...aro.org>,
        Quentin Schulz <quentin.schulz@...e-electrons.com>,
        Kevin Hilman <khilman@...libre.com>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>
Subject: Re: [PATCH v5 00/10] clk: implement clock rate protection mechanism

On Tue, 2017-12-19 at 16:38 -0800, Michael Turquette wrote:
> Applied to clk-protect-rate,

Thx !

>  with the exception that I did not apply
> "clk: fix CLK_SET_RATE_GATE with clock rate protection" as it breaks
> qcom clk code.

Here is a reminder of what I found at the time (so you don't to dig in your
mailbox for it)

Regressions reported by Kci on the following platforms:
* qcom-apq8064-cm-qs600
* qcom-apq8064-ifc6410

it seems the problem is coming from the clock used by the mmc driver
(drivers/mmc/host/mmci.c)

the driver does following sequence:
* get_clk
* prepare_enable
* get_rate
* set_rate
* ...

with clock SDCx_clk (qcom_apq8064.dtsi:1037). This clock has CLK_SET_RATE_PARENT
flag so it will transmit the request to its parent.
The parent of this clock is SDCx_src which has the CLK_SET_RATE_GATE flag.

> 
> Stephen, do you plan to fix up the qcom clock code so that the
> SET_RATE_GATE improvement can go in?
> 
> Thanks,
> Mike