linux-kernel - Re: [PATCH v2 2/2] clk: mediatek: mt8365: Fix index issue

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Date:   Fri, 26 May 2023 10:33:30 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Alexandre Mergnat <amergnat@...libre.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Chen-Yu Tsai <wenst@...omium.org>
Cc:     Markus Schneider-Pargmann <msp@...libre.com>,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH v2 2/2] clk: mediatek: mt8365: Fix index issue

Il 25/05/23 16:50, Alexandre Mergnat ha scritto:
> Before the patch [1], the clock probe was done directly in the
> clk-mt8365 driver. In this probe function, the array which stores the
> data clocks is sized using the higher defined numbers (*_NR_CLOCK) in
> the clock lists [2]. Currently, with the patch [1], the specific
> clk-mt8365 probe function is replaced by the mtk generic one [3], which
> size the clock data array by adding all the clock descriptor array size
> provided by the clk-mt8365 driver.
> 
> Actually, all clock indexes come from the header file [2], that mean, if
> there are more clock (then more index) in the header file [2] than the
> number of clock declared in the clock descriptor arrays (which is the
> case currently), the clock data array will be undersized and then the
> generic probe function will overflow when it will try to write in
> "clk_data[CLK_INDEX]". Actually, instead of crashing at boot, the probe
> function returns an error in the log which looks like:
> "of_clk_hw_onecell_get: invalid index 135", then this clock isn't
> enabled.
> 
> Solve this issue by adding in the driver the missing clocks declared in
> the header clock file [2].
> 
> [1]: Commit ffe91cb28f6a ("clk: mediatek: mt8365: Convert to
>       mtk_clk_simple_{probe,remove}()")
> [2]: include/dt-bindings/clock/mediatek,mt8365-clk.h
> [3]: drivers/clk/mediatek/clk-mtk.c
> 
> Fixes: ffe91cb28f6a ("clk: mediatek: mt8365: Convert to mtk_clk_simple_{probe,remove}()")

This is not fixing the conversion, but the clock driver, as it originally missed
clock entries and hence was not compliant with its binding (header).
It worked before, probably, but this doesn't mean that this driver didn't contain
a logic mistake from the beginning :-)

So, add (or replace the current one with) the relevant Fixes tag...

Cheers,
Angelo