linux-kernel - Re: [PATCH 5/5] mmc: mtk-sd: Assign src_clk parent to src_clk

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Message-ID: <CAPDyKFpX7_EfnDup-ZvG=9H36Ok3tvnBdS_Q+e4RcAYMN1K_KQ@mail.gmail.com>
Date:   Tue, 28 Dec 2021 17:57:41 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
Cc:     chaotian.jing@...iatek.com, matthias.bgg@...il.com,
        linux-mmc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel@...labora.com
Subject: Re: [PATCH 5/5] mmc: mtk-sd: Assign src_clk parent to src_clk_cg for
 legacy DTs

On Thu, 16 Dec 2021 at 13:57, AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com> wrote:
>
> In commit 3c1a88443698 ("mmc: mediatek: add support of source_cg clock")
> an independent cg was introduced to avoid a hardware hang issue during
> clock mode switches (subsequent commits will set that clock as optional).
>
> When this clock is not present in device-tree, any operation is being
> done on src_clk's parent (calling clk_get_parent()): to simplify this
> and avoid checking for src_clk_cg presence everytime, just assign the
> parent clock to src_clk_cg and remove the now useless checks.
>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>

The series applied for next, thanks!

Kind regards
Uffe


> ---
>  drivers/mmc/host/mtk-sd.c | 28 ++++++++++++++++------------
>  1 file changed, 16 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
> index 59d7decc3051..65037e1d7723 100644
> --- a/drivers/mmc/host/mtk-sd.c
> +++ b/drivers/mmc/host/mtk-sd.c
> @@ -901,14 +901,8 @@ static void msdc_set_mclk(struct msdc_host *host, unsigned char timing, u32 hz)
>                 }
>         }
>         sdr_clr_bits(host->base + MSDC_CFG, MSDC_CFG_CKPDN);
> -       /*
> -        * As src_clk/HCLK use the same bit to gate/ungate,
> -        * So if want to only gate src_clk, need gate its parent(mux).
> -        */
> -       if (host->src_clk_cg)
> -               clk_disable_unprepare(host->src_clk_cg);
> -       else
> -               clk_disable_unprepare(clk_get_parent(host->src_clk));
> +
> +       clk_disable_unprepare(host->src_clk_cg);
>         if (host->dev_comp->clk_div_bits == 8)
>                 sdr_set_field(host->base + MSDC_CFG,
>                               MSDC_CFG_CKMOD | MSDC_CFG_CKDIV,
> @@ -917,11 +911,8 @@ static void msdc_set_mclk(struct msdc_host *host, unsigned char timing, u32 hz)
>                 sdr_set_field(host->base + MSDC_CFG,
>                               MSDC_CFG_CKMOD_EXTRA | MSDC_CFG_CKDIV_EXTRA,
>                               (mode << 12) | div);
> -       if (host->src_clk_cg)
> -               clk_prepare_enable(host->src_clk_cg);
> -       else
> -               clk_prepare_enable(clk_get_parent(host->src_clk));
>
> +       clk_prepare_enable(host->src_clk_cg);
>         readl_poll_timeout(host->base + MSDC_CFG, val, (val & MSDC_CFG_CKSTB), 0, 0);
>         sdr_set_bits(host->base + MSDC_CFG, MSDC_CFG_CKPDN);
>         mmc->actual_clock = sclk;
> @@ -2530,6 +2521,19 @@ static int msdc_of_clock_parse(struct platform_device *pdev,
>         if (IS_ERR(host->src_clk_cg))
>                 return PTR_ERR(host->src_clk_cg);
>
> +       /*
> +        * Fallback for legacy device-trees: src_clk and HCLK use the same
> +        * bit to control gating but they are parented to a different mux,
> +        * hence if our intention is to gate only the source, required
> +        * during a clk mode switch to avoid hw hangs, we need to gate
> +        * its parent (specified as a different clock only on new DTs).
> +        */
> +       if (!host->src_clk_cg) {
> +               host->src_clk_cg = clk_get_parent(host->src_clk);
> +               if (IS_ERR(host->src_clk_cg))
> +                       return PTR_ERR(host->src_clk_cg);
> +       }
> +
>         host->sys_clk_cg = devm_clk_get_optional(&pdev->dev, "sys_cg");
>         if (IS_ERR(host->sys_clk_cg))
>                 host->sys_clk_cg = NULL;
> --
> 2.33.1
>