On 20 December 2017 at 11:50, Maxime Ripard
<maxime.ripard@xxxxxxxxxxxxxxxxxx> wrote:
> So far, even if our card was not in use, we didn't shut down our main
> clock, which meant that it was still output on the MMC bus.
>
> While this obviously means that we could save some power there, it also
> created issues when it comes with EMC control since we'll have a perfect
> peak at the card clock rate.
>
> Let's implement runtime_pm with autosuspend so that we will shut down the
> clock when it's not been in use for quite some time.
>
> Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/mmc/host/sunxi-mmc.c | 90 ++++++++++++++++++++++++-------------
> 1 file changed, 60 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c
> index 3ce46ebd3488..c6a0bd0e0476 100644
> --- a/drivers/mmc/host/sunxi-mmc.c
> +++ b/drivers/mmc/host/sunxi-mmc.c
> @@ -35,6 +35,7 @@
> #include <linux/of_gpio.h>
> #include <linux/of_platform.h>
> #include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> #include <linux/regulator/consumer.h>
> #include <linux/reset.h>
> #include <linux/scatterlist.h>
> @@ -1217,29 +1218,11 @@ static int sunxi_mmc_resource_request(struct sunxi_mmc_host *host,
> return ret;
> }
>
> - ret = clk_prepare_enable(host->clk_mmc);
> - if (ret) {
> - dev_err(&pdev->dev, "Enable mmc clk err %d\n", ret);
> - goto error_disable_clk_ahb;
> - }
> -
> - ret = clk_prepare_enable(host->clk_output);
> - if (ret) {
> - dev_err(&pdev->dev, "Enable output clk err %d\n", ret);
> - goto error_disable_clk_mmc;
> - }
> -
> - ret = clk_prepare_enable(host->clk_sample);
> - if (ret) {
> - dev_err(&pdev->dev, "Enable sample clk err %d\n", ret);
> - goto error_disable_clk_output;
> - }
> -
Actually, I think you should keep all the above. Perhaps you may want
to move it to a separate helper function though, which the
->runtime_resume() callbacks can invoke as well.
More reasons to why, see the comment in the ->probe() function.
> if (!IS_ERR(host->reset)) {
> ret = reset_control_reset(host->reset);
> if (ret) {
> dev_err(&pdev->dev, "reset err %d\n", ret);
> - goto error_disable_clk_sample;
> + goto error_disable_clk_ahb;
> }
> }
>
> @@ -1258,12 +1241,6 @@ static int sunxi_mmc_resource_request(struct sunxi_mmc_host *host,
> error_assert_reset:
> if (!IS_ERR(host->reset))
> reset_control_assert(host->reset);
> -error_disable_clk_sample:
> - clk_disable_unprepare(host->clk_sample);
> -error_disable_clk_output:
> - clk_disable_unprepare(host->clk_output);
> -error_disable_clk_mmc:
> - clk_disable_unprepare(host->clk_mmc);
> error_disable_clk_ahb:
> clk_disable_unprepare(host->clk_ahb);
> return ret;
> @@ -1280,6 +1257,7 @@ static int sunxi_mmc_probe(struct platform_device *pdev)
> dev_err(&pdev->dev, "mmc alloc host failed\n");
> return -ENOMEM;
> }
> + platform_set_drvdata(pdev, mmc);
>
> host = mmc_priv(mmc);
> host->mmc = mmc;
> @@ -1340,12 +1318,16 @@ static int sunxi_mmc_probe(struct platform_device *pdev)
> if (ret)
> goto error_free_dma;
>
> + pm_runtime_set_autosuspend_delay(&pdev->dev, 50);
> + pm_runtime_use_autosuspend(&pdev->dev);
> + pm_runtime_enable(&pdev->dev);
> +
This means in case you don't have CONFIG_PM set when compiling this
driver, the clocks will never be enabled using runtime PM.
I think it's good practice to deal with this, therefore I think you
should enable the clocks as before, and instead indicate that the
device is already runtime resumed.
In other words, before you call pm_runtime_enable(), invoke
pm_runtime_set_active().
> ret = mmc_add_host(mmc);
> if (ret)
> goto error_free_dma;
>
> dev_info(&pdev->dev, "base:0x%p irq:%u\n", host->reg_base, host->irq);
> - platform_set_drvdata(pdev, mmc);
> +
> return 0;
>
> error_free_dma:
> @@ -1361,27 +1343,75 @@ static int sunxi_mmc_remove(struct platform_device *pdev)
> struct sunxi_mmc_host *host = mmc_priv(mmc);
>
> mmc_remove_host(mmc);
> + pm_runtime_force_suspend(&pdev->dev);
Do you need the clocks to be enabled, while calling disable_irq() and
sunxi_mmc_reset_host()?
In such case you need to call pm_runtime_get_sync() here. Then move
pm_runtime_force_suspend() a few lines below, and later call
pm_runtime_put_noidle().
> disable_irq(host->irq);
> sunxi_mmc_reset_host(host);
>
> if (!IS_ERR(host->reset))
> reset_control_assert(host->reset);
>
> - clk_disable_unprepare(host->clk_sample);
> + dma_free_coherent(&pdev->dev, PAGE_SIZE, host->sg_cpu, host->sg_dma);
> + mmc_free_host(mmc);
> +
> + return 0;
> +}
> +
> +static int sunxi_mmc_runtime_resume(struct device *dev)
> +{
> + struct mmc_host *mmc = dev_get_drvdata(dev);
> + struct sunxi_mmc_host *host = mmc_priv(mmc);
> + int ret;
> +
> + ret = clk_prepare_enable(host->clk_mmc);
> + if (ret) {
> + dev_err(dev, "Enable mmc clk err %d\n", ret);
> + return ret;
> + }
> +
> + ret = clk_prepare_enable(host->clk_output);
> + if (ret) {
> + dev_err(dev, "Enable output clk err %d\n", ret);
> + goto error_disable_clk_mmc;
> + }
> +
> + ret = clk_prepare_enable(host->clk_sample);
> + if (ret) {
> + dev_err(dev, "Enable sample clk err %d\n", ret);
> + goto error_disable_clk_output;
> + }
> +
> + return 0;
> +
> +error_disable_clk_output:
> clk_disable_unprepare(host->clk_output);
> +error_disable_clk_mmc:
> clk_disable_unprepare(host->clk_mmc);
> - clk_disable_unprepare(host->clk_ahb);
> + return ret;
> +}
>
> - dma_free_coherent(&pdev->dev, PAGE_SIZE, host->sg_cpu, host->sg_dma);
> - mmc_free_host(mmc);
> +static int sunxi_mmc_runtime_suspend(struct device *dev)
> +{
> + struct mmc_host *mmc = dev_get_drvdata(dev);
> + struct sunxi_mmc_host *host = mmc_priv(mmc);
> +
> + clk_disable_unprepare(host->clk_sample);
> + clk_disable_unprepare(host->clk_output);
> + clk_disable_unprepare(host->clk_mmc);
>
> return 0;
> }
>
> +static const struct dev_pm_ops sunxi_mmc_pm_ops = {
> + SET_RUNTIME_PM_OPS(sunxi_mmc_runtime_suspend,
> + sunxi_mmc_runtime_resume,
> + NULL)
> +};
> +
> static struct platform_driver sunxi_mmc_driver = {
> .driver = {
> .name = "sunxi-mmc",
> .of_match_table = of_match_ptr(sunxi_mmc_of_match),
> + .pm = &sunxi_mmc_pm_ops,
> },
> .probe = sunxi_mmc_probe,
> .remove = sunxi_mmc_remove,
> --
> git-series 0.9.1
Otherwise this looks good to me!
BTW, isn't system wide suspend/resume() also important to save power
for? That's rather simple to implement, after you have enabled runtime
PM support.
Kind regards
Uffe
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