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In-Reply-To: <20231103102533.69280-2-angelogioacchino.delregno@collabora.com>
From:   Fei Shao <fshao@chromium.org>
Date:   Thu, 23 Nov 2023 12:03:16 +0800
Message-ID: <CAC=S1nhS_OckB3ap9Sq1U9D5b7605N=w4WyPjJoRJCSRxW5_5g@mail.gmail.com>
Subject: Re: [PATCH v3 1/3] clk: mediatek: clk-mux: Support custom parent
 indices for muxes
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
Cc:     sboyd@kernel.org, mturquette@baylibre.com, matthias.bgg@gmail.com,
        wenst@chromium.org, msp@baylibre.com, amergnat@baylibre.com,
        yangyingliang@huawei.com, u.kleine-koenig@pengutronix.de,
        linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, kernel@collabora.com
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On Fri, Nov 3, 2023 at 6:25=E2=80=AFPM AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.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=3D0
>   - parent2; idx=3D1
>   - parent3; idx=3D2
>
> - MUX1 (wanted parents)
>   - parent1; idx=3D0
>   - parent3; idx=3D2
>
> 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@baylibre.com>
> Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@coll=
abora.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@chromium.org>
Tested-by: Fei Shao <fshao@chromium.org>