linux-kernel - Re: [PATCH 2/2] mmc: sdhci-msm: Enable delay circuit calibration clocks

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Message-ID: <CAPDyKFphMcVfbPUacG-iJEhwT0m6uKXFs6wjgS=YXOK2c_bqEA@mail.gmail.com>
Date:   Tue, 22 Aug 2017 12:45:43 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
        Venkat Gopalakrishnan <venkatg@...eaurora.org>,
        Ritesh Harjani <riteshh@...eaurora.org>
Subject: Re: [PATCH 2/2] mmc: sdhci-msm: Enable delay circuit calibration clocks

[...]

> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
> index 71e01cbc38b6..7b47906ba447 100644
> --- a/drivers/mmc/host/sdhci-msm.c
> +++ b/drivers/mmc/host/sdhci-msm.c
> @@ -131,7 +131,7 @@ struct sdhci_msm_host {
>         struct clk *pclk;       /* SDHC peripheral bus clock */
>         struct clk *bus_clk;    /* SDHC bus voter clock */
>         struct clk *xo_clk;     /* TCXO clk needed for FLL feature of cm_dll*/
> -       struct clk_bulk_data bulk_clks[2];
> +       struct clk_bulk_data bulk_clks[4];
>         unsigned long clk_rate;
>         struct mmc_host *mmc;
>         bool use_14lpp_dll_reset;
> @@ -1125,6 +1125,7 @@ static int sdhci_msm_probe(struct platform_device *pdev)
>         struct sdhci_pltfm_host *pltfm_host;
>         struct sdhci_msm_host *msm_host;
>         struct resource *core_memres;
> +       struct clk *clk;
>         int ret;
>         u16 host_version, core_minor;
>         u32 core_version, config;
> @@ -1194,6 +1195,14 @@ static int sdhci_msm_probe(struct platform_device *pdev)
>         msm_host->bulk_clks[0].clk = msm_host->clk;
>         msm_host->bulk_clks[1].clk = msm_host->pclk;
>
> +       clk = devm_clk_get(&pdev->dev, "cal");
> +       if (!IS_ERR(clk))
> +               msm_host->bulk_clks[2].clk = clk;
> +
> +       clk = devm_clk_get(&pdev->dev, "sleep");
> +       if (!IS_ERR(clk))
> +               msm_host->bulk_clks[3].clk = clk;
> +

First, both these clocks needs to be documented in DT doc.

Second, I think you should initialize bulk_clks[2|3] to NULL, in case
the new optional clocks can't be fetched.

>         ret = clk_bulk_prepare_enable(ARRAY_SIZE(msm_host->bulk_clks),
>                                       msm_host->bulk_clks);
>         if (ret)
> --
> 2.12.0
>

Another observation is the number of clocks for this device. In some
cases, now six clocks are needed!? Is that really correct? Just wanted
to point it out as it seems a bit too much. :-)

Kind regards
Uffe