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Date: Tue, 20 Oct 2015 11:19:17 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Shawn Lin <shawn.lin@...k-chips.com>
Cc: Michal Simek <michal.simek@...inx.com>,
Sören Brinkmann <soren.brinkmann@...inx.com>,
linux-mmc <linux-mmc@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 3/3] mmc: sdhci-of-arasan: add runtime pm support
On 20 October 2015 at 09:05, Shawn Lin <shawn.lin@...k-chips.com> wrote:
> This patch add runtime_suspend and runtime_resume for
> sdhci-of-arasan. Currently we also suspend phy at
> runtime_suspend for power-saving.
>
> Signed-off-by: Shawn Lin <shawn.lin@...k-chips.com>
> ---
>
> Changes in v2: None
>
> drivers/mmc/host/sdhci-of-arasan.c | 80 ++++++++++++++++++++++++++++++++++++--
> 1 file changed, 77 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-of-arasan.c b/drivers/mmc/host/sdhci-of-arasan.c
> index 85bd0f9d..579f7bb 100644
> --- a/drivers/mmc/host/sdhci-of-arasan.c
> +++ b/drivers/mmc/host/sdhci-of-arasan.c
> @@ -30,6 +30,8 @@
> #define CLK_CTRL_TIMEOUT_MASK (0xf << CLK_CTRL_TIMEOUT_SHIFT)
> #define CLK_CTRL_TIMEOUT_MIN_EXP 13
>
> +#define ARASAN_RPM_DELAY_MS 50
> +
> /**
> * struct sdhci_arasan_data
> * @clk_ahb: Pointer to the AHB clock
> @@ -183,8 +185,70 @@ static int sdhci_arasan_resume(struct device *dev)
> }
> #endif /* ! CONFIG_PM_SLEEP */
>
> -static SIMPLE_DEV_PM_OPS(sdhci_arasan_dev_pm_ops, sdhci_arasan_suspend,
> - sdhci_arasan_resume);
> +
> +#ifdef CONFIG_PM
> +static int sdhci_arasan_runtime_suspend(struct device *dev)
> +{
> + struct sdhci_host *host = dev_get_drvdata(dev);
> + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> + struct sdhci_arasan_data *sdhci_arasan = pltfm_host->priv;
> + int ret;
> +
> + ret = sdhci_runtime_suspend_host(host);
> + if (ret)
> + return ret;
> +
> + if (!IS_ERR(sdhci_arasan->phy)) {
> + ret = sdhci_arasan_suspend_phy(sdhci_arasan->phy);
> + if (ret) {
> + dev_err(dev, "Cannot suspend phy at runtime.\n");
> + sdhci_runtime_resume_host(host);
> + return ret;
> + }
> + }
> +
> + clk_disable_unprepare(sdhci_arasan->clk_ahb);
> + clk_disable_unprepare(pltfm_host->clk);
This looks correct, but comparing to the system PM callbacks clocks is
gated via clk_disable() and not via clk_disable_unprepare(). So, you
need to fix this for system PM.
> +
> + return 0;
> +}
> +
> +static int sdhci_arasan_runtime_resume(struct device *dev)
> +{
> + struct sdhci_host *host = dev_get_drvdata(dev);
> + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> + struct sdhci_arasan_data *sdhci_arasan = pltfm_host->priv;
> + int ret;
> +
> + clk_prepare_enable(pltfm_host->clk);
> + clk_prepare_enable(sdhci_arasan->clk_ahb);
> +
> + if (!IS_ERR(sdhci_arasan->phy)) {
> + ret = sdhci_arasan_resume_phy(sdhci_arasan->phy);
> + if (ret) {
> + dev_err(dev, "Cannot resume phy at runtime.\n");
> + clk_disable_unprepare(sdhci_arasan->clk_ahb);
> + clk_disable_unprepare(pltfm_host->clk);
> + return ret;
> + }
> + }
> +
> + return sdhci_runtime_resume_host(host);
The error handling in a runtime resume function sometimes tends to be
a bit tricky.
In this case you have decided to care only about the errors from the
phy API, but ignores the other ones. That isn't consistent, so I think
you need to decide if you want error handling and then for all cases,
or not.
> +}
> +#endif
> +
> +#ifdef CONFIG_PM
Remove this ifdef..
> +static const struct dev_pm_ops sdhci_arasan_pmops = {
> + SET_SYSTEM_SLEEP_PM_OPS(sdhci_arasan_suspend, sdhci_arasan_resume)
Since you enabled runtime PM, that means sdhci_arasan_suspend() can
end up being invoked when the device is runtime suspended. You don't
deal with that case.
In the ideal scenario you could assign the system PM callbacks to
pm_runtime_force_suspend|resume(), unless you have specific wakeup
settings to manage at system PM. Using this solution would solve the
above problem, in other case you need to deal with it from
sdhci_arasan_suspend|resume().
> + SET_RUNTIME_PM_OPS(sdhci_arasan_runtime_suspend,
> + sdhci_arasan_runtime_resume, NULL)
> +};
> +
... and everything below towards the endif.
Then use the reference of sdhci_arasan_pmops directly when needed below instead.
The minor overhead of having an empty sdhci_arasan_pmops struct when
CONFIG_PM isn't set can be neglected.
> +#define SDHCI_ARASAN_PMOPS (&sdhci_arasan_pmops)
> +
> +#else
> +#define SDHCI_ARASAN_PMOPS NULL
> +#endif
>
> static int sdhci_arasan_probe(struct platform_device *pdev)
> {
> @@ -272,6 +336,11 @@ static int sdhci_arasan_probe(struct platform_device *pdev)
> goto clk_disable_all;
> }
>
> + pm_runtime_set_autosuspend_delay(&pdev->dev, ARASAN_RPM_DELAY_MS);
> + pm_runtime_use_autosuspend(&pdev->dev);
pm_runtime_set_active() is missing.
> + pm_runtime_enable(&pdev->dev);
> + pm_suspend_ignore_children(&pdev->dev, 1);
> +
> ret = sdhci_add_host(host);
> if (ret)
> goto err_pltfm_free;
> @@ -279,6 +348,7 @@ static int sdhci_arasan_probe(struct platform_device *pdev)
> return 0;
>
> err_pltfm_free:
> + pm_runtime_disable(&pdev->dev);
> sdhci_pltfm_free(pdev);
> clk_disable_all:
> clk_disable_unprepare(clk_xin);
> @@ -297,6 +367,10 @@ static int sdhci_arasan_remove(struct platform_device *pdev)
> if (!IS_ERR(sdhci_arasan->phy))
> phy_exit(sdhci_arasan->phy);
>
> + pm_runtime_get_sync(&pdev->dev);
> + pm_runtime_dont_use_autosuspend(&pdev->dev);
pm_runtime_dont_use_autosuspend() shouldn't be needed here I think.
> + pm_runtime_disable(&pdev->dev);
> +
> clk_disable_unprepare(sdhci_arasan->clk_ahb);
>
> return sdhci_pltfm_unregister(pdev);
> @@ -314,7 +388,7 @@ static struct platform_driver sdhci_arasan_driver = {
> .driver = {
> .name = "sdhci-arasan",
> .of_match_table = sdhci_arasan_of_match,
> - .pm = &sdhci_arasan_dev_pm_ops,
> + .pm = SDHCI_ARASAN_PMOPS,
> },
> .probe = sdhci_arasan_probe,
> .remove = sdhci_arasan_remove,
> --
> 2.3.7
>
>
> --
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Kind regards
Uffe
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