linux-kernel - Re: [PATCH V4] mmc: sdhci-msm: Update system suspend/resume callbacks of sdhci-msm platform driver

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Date:   Wed, 4 Mar 2020 16:34:29 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Shaik Sajida Bhanu <sbhanu@...eaurora.org>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        Rob Herring <robh+dt@...nel.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Asutosh Das <asutoshd@...eaurora.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Sahitya Tummala <stummala@...eaurora.org>,
        Sayali Lokhande <sayalil@...eaurora.org>, cang@...eaurora.org,
        Veerabhadrarao Badiganti <vbadigan@...eaurora.org>,
        Ram Prakash Gupta <rampraka@...eaurora.org>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        DTML <devicetree@...r.kernel.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Subject: Re: [PATCH V4] mmc: sdhci-msm: Update system suspend/resume callbacks
 of sdhci-msm platform driver

On Thu, 20 Feb 2020 at 07:45, Shaik Sajida Bhanu <sbhanu@...eaurora.org> wrote:
>
> The existing suspend/resume callbacks of sdhci-msm driver are just
> gating/un-gating the clocks. During suspend cycle more can be done
> like disabling controller, disabling card detection, enabling wake-up events.
>
> So updating the system pm callbacks for performing these extra
> actions besides controlling the clocks.
>
> Signed-off-by: Shaik Sajida Bhanu <sbhanu@...eaurora.org>
> Reviewed-by: Stephen Boyd <swboyd@...omium.org>
> ---
> Changes since V3:
>     Invoking sdhci & cqhci resume if sdhci_host_suspend fails.
>     Removed condition check before invoking cqhci_resume since its a dummy function.
>
> Changes since V2:
>     Removed disabling/enabling pwr-irq from system pm ops.
>
> Changes since V1:
>     Invoking pm_runtime_force_suspend/resume instead of
>     sdhci_msm_runtime_suepend/resume.
> ---
>  drivers/mmc/host/sdhci-msm.c | 47 ++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 45 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
> index 3955fa5d..3559b50 100644
> --- a/drivers/mmc/host/sdhci-msm.c
> +++ b/drivers/mmc/host/sdhci-msm.c
> @@ -2159,9 +2159,52 @@ static __maybe_unused int sdhci_msm_runtime_resume(struct device *dev)
>         return 0;
>  }
>
> +static int sdhci_msm_suspend(struct device *dev)
> +{
> +       struct sdhci_host *host = dev_get_drvdata(dev);
> +       int ret;
> +
> +       if (host->mmc->caps2 & MMC_CAP2_CQE) {
> +               ret = cqhci_suspend(host->mmc);
> +               if (ret)
> +                       return ret;
> +       }
> +
> +       ret = sdhci_suspend_host(host);
> +       if (ret)
> +               goto resume_cqhci;

sdhci_suspend_host() can't be called on a device that has been runtime
suspended, as that would lead to accessing device registers when
clocks/PM domains are gated.

Depending on how the corresponding cqhci device is managed from a
runtime PM point of view, it could also be problematic to call
cqhci_suspend().

> +
> +       ret = pm_runtime_force_suspend(dev);

It looks to me that perhaps you could make use of solely
pm_runtime_force_suspend(), then just skip calling
sdhci_suspend|resume_host() altogether. Do you think that could work?

And vice versa for sdhci_msm_resume(), of course.

> +       if (!ret)
> +               return ret;
> +
> +       sdhci_resume_host(host);
> +
> +resume_cqhci:
> +       cqhci_resume(host->mmc);
> +       return ret;
> +}
> +
> +static int sdhci_msm_resume(struct device *dev)
> +{
> +       struct sdhci_host *host = dev_get_drvdata(dev);
> +       int ret;
> +
> +       ret = pm_runtime_force_resume(dev);
> +       if (ret)
> +               return ret;
> +
> +       ret = sdhci_resume_host(host);
> +       if (ret < 0)
> +               return ret;
> +
> +       ret = cqhci_resume(host->mmc);
> +       return ret;
> +}
> +
>  static const struct dev_pm_ops sdhci_msm_pm_ops = {
> -       SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> -                               pm_runtime_force_resume)
> +       SET_SYSTEM_SLEEP_PM_OPS(sdhci_msm_suspend,
> +                               sdhci_msm_resume)
>         SET_RUNTIME_PM_OPS(sdhci_msm_runtime_suspend,
>                            sdhci_msm_runtime_resume,
>                            NULL)
> --
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
> of Code Aurora Forum, hosted by The Linux Foundation
>

Kind regards
Uffe