linux-kernel - Re: [PATCH] mmc: sdhci-msm: Warn about overclocking SD/MMC

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Date:   Thu, 10 Dec 2020 13:03:25 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     Adrian Hunter <adrian.hunter@...el.com>,
        Douglas Anderson <dianders@...omium.org>,
        Ulf Hansson <ulf.hansson@...aro.org>
Cc:     vbadigan@...eaurora.org, Taniya Das <tdas@...eaurora.org>,
        Douglas Anderson <dianders@...omium.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mmc@...r.kernel.org
Subject: Re: [PATCH] mmc: sdhci-msm: Warn about overclocking SD/MMC

Quoting Douglas Anderson (2020-12-10 12:57:25)
> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
> index 3451eb325513..dd41f6a4dbfb 100644
> --- a/drivers/mmc/host/sdhci-msm.c
> +++ b/drivers/mmc/host/sdhci-msm.c
> @@ -353,6 +353,7 @@ static void msm_set_clock_rate_for_bus_mode(struct sdhci_host *host,
>         struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
>         struct mmc_ios curr_ios = host->mmc->ios;
>         struct clk *core_clk = msm_host->bulk_clks[0].clk;
> +       unsigned int achieved_rate;

unsigned long?

>         int rc;
>  
>         clock = msm_get_clock_rate_for_bus_mode(host, clock);
> @@ -363,6 +364,17 @@ static void msm_set_clock_rate_for_bus_mode(struct sdhci_host *host,
>                        curr_ios.timing);
>                 return;
>         }
> +
> +       /*
> +        * Qualcomm clock drivers by default round clock _up_ if they can't
> +        * make the requested rate.  This is not good for SD.  Yell if we
> +        * encounter it.
> +        */
> +       achieved_rate = clk_get_rate(core_clk);
> +       if (achieved_rate > clock)
> +               pr_warn("%s: Card appears overclocked; req %u Hz, actual %d Hz\n",

Can we use dev_warn?

dev_warn(mmc_dev(mmc)
dev_warn(&msm_host->pdev->dev

?

> +                       mmc_hostname(host->mmc), clock, achieved_rate);
> +
>         msm_host->clk_rate = clock;
>         pr_debug("%s: Setting clock at rate %lu at timing %d\n",
>                  mmc_hostname(host->mmc), clk_get_rate(core_clk),

This could use achieved_rate now.