linux-kernel - Re: [PATCH v3 1/3] clk: mediatek: clk-mux: Support custom parent indices for muxes

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Date:   Thu, 23 Nov 2023 12:03:16 +0800
From:   Fei Shao <fshao@...omium.org>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
Cc:     sboyd@...nel.org, mturquette@...libre.com, matthias.bgg@...il.com,
        wenst@...omium.org, msp@...libre.com, amergnat@...libre.com,
        yangyingliang@...wei.com, u.kleine-koenig@...gutronix.de,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, kernel@...labora.com
Subject: Re: [PATCH v3 1/3] clk: mediatek: clk-mux: Support custom parent
 indices for muxes

On Fri, Nov 3, 2023 at 6:25 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com> wrote:
>
> Add support for customized parent indices for MediaTek muxes: this is
> necessary for the case in which we want to exclude some clocks from
> a mux's parent clocks list, where the exclusions are not from the
> very bottom of the list but either in the middle or the beginning.
>
> Example:
> - MUX1 (all parents)
>   - parent1; idx=0
>   - parent2; idx=1
>   - parent3; idx=2
>
> - MUX1 (wanted parents)
>   - parent1; idx=0
>   - parent3; idx=2
>
> To achieve that add a `parent_index` array pointer to struct mtk_mux,
> then in .set_parent(), .get_parent() callbacks check if this array
> was populated and eventually get the index from that.
>
> Also, to avoid updating all clock drivers for all SoCs, rename the
> "main" macro to __GATE_CLR_SET_UPD_FLAGS (so, `__` was added) and
> add the new member to it; furthermore, GATE_CLK_SET_UPD_FLAGS has
> been reintroduced as being fully compatible with the older version.
>
> The new parent_index can be specified with the new `_INDEXED`
> variants of the MUX_GATE_CLR_SET_UPD_xxxx macros.
>
> Reviewed-by: Alexandre Mergnat <amergnat@...libre.com>
> Reviewed-by: Chen-Yu Tsai <wenst@...omium.org>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>

Tested on MT8188 with a Type-C -> DP adapter to an extended display
Gigabyte M32U.
The DP output reacts smoothly to resolution switch and refresh rate
change, and the internal eDP output also never freezes.

Reviewed-by: Fei Shao <fshao@...omium.org>
Tested-by: Fei Shao <fshao@...omium.org>