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Message-ID: <16047c7a-5bd1-868c-e6eb-e5f415e77fdd@intel.com>
Date: Thu, 10 Aug 2023 11:12:49 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Liming Sun <limings@...dia.com>,
Ulf Hansson <ulf.hansson@...aro.org>,
David Thompson <davthompson@...dia.com>,
Shawn Lin <shawn.lin@...k-chips.com>
Cc: linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7] mmc: sdhci-of-dwcmshc: Add runtime PM operations
On 8/08/23 23:23, Liming Sun wrote:
> This commit implements the runtime PM operations to disable eMMC
> card clock when idle.
>
> Reviewed-by: David Thompson <davthompson@...dia.com>
> Signed-off-by: Liming Sun <limings@...dia.com>
> ---
> v6->v7:
> - Address Ulf's comment;
> v5->v6:
> - Address Adrian's more comments and add coordination between
> runtime PM and system PM;
> v4->v5:
> - Address Adrian's comment to move the pm_enable to the end to
> avoid race;
> v3->v4:
> - Fix compiling reported by 'kernel test robot';
> v2->v3:
> - Revise the commit message;
> v1->v2:
> Updates for comments from Ulf:
> - Make the runtime PM logic generic for sdhci-of-dwcmshc;
> v1: Initial version.
> ---
> drivers/mmc/host/sdhci-of-dwcmshc.c | 72 ++++++++++++++++++++++++++++-
> 1 file changed, 70 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
> index e68cd87998c8..c8e145031429 100644
> --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
> +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
> @@ -15,6 +15,7 @@
> #include <linux/module.h>
> #include <linux/of.h>
> #include <linux/of_device.h>
> +#include <linux/pm_runtime.h>
> #include <linux/reset.h>
> #include <linux/sizes.h>
>
> @@ -548,9 +549,13 @@ static int dwcmshc_probe(struct platform_device *pdev)
>
> host->mmc->caps |= MMC_CAP_WAIT_WHILE_BUSY;
>
> + pm_runtime_get_noresume(dev);
> + pm_runtime_set_active(dev);
> + pm_runtime_enable(dev);
> +
> err = sdhci_setup_host(host);
> if (err)
> - goto err_clk;
> + goto err_rpm;
>
> if (rk_priv)
> dwcmshc_rk35xx_postinit(host, priv);
> @@ -559,10 +564,15 @@ static int dwcmshc_probe(struct platform_device *pdev)
> if (err)
> goto err_setup_host;
>
> + pm_runtime_put(dev);
> +
> return 0;
>
> err_setup_host:
> sdhci_cleanup_host(host);
> +err_rpm:
> + pm_runtime_disable(dev);
> + pm_runtime_put_noidle(dev);
> err_clk:
> clk_disable_unprepare(pltfm_host->clk);
> clk_disable_unprepare(priv->bus_clk);
> @@ -606,6 +616,12 @@ static int dwcmshc_suspend(struct device *dev)
> if (ret)
> return ret;
>
> + ret = pm_runtime_force_suspend(dev);
> + if (ret) {
> + sdhci_resume_host(host);
> + return ret;
> + }
Since you are only using the runtime PM callbacks to turn off the card
clock via SDHCI_CLOCK_CONTROL, pm_runtime_force_suspend() and
pm_runtime_force_resume() are not needed at all.
sdhci_suspend_host() does not care if SDHCI_CLOCK_CARD_EN is on or off.
(And you are disabling pltfm_host->clk and priv->bus_clk, so presumably
the result is no clock either way)
sdhci_resume_host() does not restore state unless
SDHCI_QUIRK2_HOST_OFF_CARD_ON is used, it just resets, so the internal clock
SDHCI_CLOCK_INT_EN is off which is consistent with either runtime suspended
or runtime resumed.
So it just needs some comments, for example:
+/*
+ * Note, runtime suspend changes only SDHCI_CLOCK_CARD_EN which has no effect on
+ * system suspend.
+ */
static int dwcmshc_suspend(struct device *dev)
+/*
+ * Note, system resume leaves SDHCI_CLOCK_INT_EN off which is consistent with
+ * either runtime suspended or runtime resumed.
+ */
static int dwcmshc_resume(struct device *dev)
> +
> clk_disable_unprepare(pltfm_host->clk);
> if (!IS_ERR(priv->bus_clk))
> clk_disable_unprepare(priv->bus_clk);
> @@ -625,6 +641,10 @@ static int dwcmshc_resume(struct device *dev)
> struct rk35xx_priv *rk_priv = priv->priv;
> int ret;
>
> + ret = pm_runtime_force_resume(dev);
> + if (ret)
> + return ret;
> +
> ret = clk_prepare_enable(pltfm_host->clk);
> if (ret)
> return ret;
> @@ -646,7 +666,55 @@ static int dwcmshc_resume(struct device *dev)
> }
> #endif
>
> -static SIMPLE_DEV_PM_OPS(dwcmshc_pmops, dwcmshc_suspend, dwcmshc_resume);
> +#ifdef CONFIG_PM
> +
> +static void dwcmshc_enable_card_clk(struct sdhci_host *host)
> +{
> + u16 ctrl;
> +
> + ctrl = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> + if ((ctrl & SDHCI_CLOCK_INT_EN) && !(ctrl & SDHCI_CLOCK_CARD_EN)) {
> + ctrl |= SDHCI_CLOCK_CARD_EN;
> + sdhci_writew(host, ctrl, SDHCI_CLOCK_CONTROL);
> + }
> +}
> +
> +static void dwcmshc_disable_card_clk(struct sdhci_host *host)
> +{
> + u16 ctrl;
> +
> + ctrl = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> + if (ctrl & SDHCI_CLOCK_CARD_EN) {
> + ctrl &= ~SDHCI_CLOCK_CARD_EN;
> + sdhci_writew(host, ctrl, SDHCI_CLOCK_CONTROL);
> + }
> +}
> +
> +static int dwcmshc_runtime_suspend(struct device *dev)
> +{
> + struct sdhci_host *host = dev_get_drvdata(dev);
> +
> + dwcmshc_disable_card_clk(host);
> +
> + return 0;
> +}
> +
> +static int dwcmshc_runtime_resume(struct device *dev)
> +{
> + struct sdhci_host *host = dev_get_drvdata(dev);
> +
> + dwcmshc_enable_card_clk(host);
> +
> + return 0;
> +}
> +
> +#endif
> +
> +static const struct dev_pm_ops dwcmshc_pmops = {
> + SET_SYSTEM_SLEEP_PM_OPS(dwcmshc_suspend, dwcmshc_resume)
> + SET_RUNTIME_PM_OPS(dwcmshc_runtime_suspend,
> + dwcmshc_runtime_resume, NULL)
> +};
>
> static struct platform_driver sdhci_dwcmshc_driver = {
> .driver = {
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