On Tue, Feb 16, 2016 at 03:38:29PM +0100, Ulf Hansson wrote:
> On 13 February 2016 at 10:56, Ludovic Desroches
> <ludovic.desroches@xxxxxxxxx> wrote:
> > When suspending the sdhci host, the only hardware event that could wake
> > up the host is a sdio irq if they are enabled. If we want to wakeup on
> > card detect events, a gpio as to be used.
> > If we don't want to use a gpio but the card detect pio of the controller
> > then we need to keep enabled the clock of the controller interface to
> > get the interrupt and to not set the host in a suspended state to have the
> > interrupt handled.
> >
> > Signed-off-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxx>
> > ---
> > drivers/mmc/host/sdhci-of-at91.c | 46 ++++++++++++++++++++++++++++++----------
> > 1 file changed, 35 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/mmc/host/sdhci-of-at91.c b/drivers/mmc/host/sdhci-of-at91.c
> > index efec736..2159c6e 100644
> > --- a/drivers/mmc/host/sdhci-of-at91.c
> > +++ b/drivers/mmc/host/sdhci-of-at91.c
> > @@ -18,6 +18,7 @@
> > #include <linux/err.h>
> > #include <linux/io.h>
> > #include <linux/mmc/host.h>
> > +#include <linux/mmc/slot-gpio.h>
> > #include <linux/module.h>
> > #include <linux/of.h>
> > #include <linux/of_device.h>
> > @@ -45,7 +46,6 @@ static const struct sdhci_ops sdhci_at91_sama5d2_ops = {
> >
> > static const struct sdhci_pltfm_data soc_data_sama5d2 = {
> > .ops = &sdhci_at91_sama5d2_ops,
> > - .quirks = SDHCI_QUIRK_BROKEN_CARD_DETECTION,
>
> You probably have some leftovers from earlier local changes, as this
> isn't going to apply to my next branch.
>
Yes, it is based on the first patch of this thread, it was only to
discuss about it.
> > .quirks2 = SDHCI_QUIRK2_NEED_DELAY_AFTER_INT_CLK_RST,
> > };
> >
> > @@ -55,17 +55,37 @@ static const struct of_device_id sdhci_at91_dt_match[] = {
> > };
> >
> > #ifdef CONFIG_PM
> > +static bool sdhci_at91_use_sdhci_runtime(struct sdhci_host *host)
> > +{
> > + u32 caps = host->mmc->caps;
> > +
> > + return (caps & MMC_CAP_NONREMOVABLE) ||
> > + (!IS_ERR_VALUE(mmc_gpio_get_cd(host->mmc)));
> > +}
> > +
> > static int sdhci_at91_runtime_suspend(struct device *dev)
> > {
> > struct sdhci_host *host = dev_get_drvdata(dev);
> > struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> > struct sdhci_at91_priv *priv = pltfm_host->priv;
> > - int ret;
> > + int ret = 0;
> >
> > - ret = sdhci_runtime_suspend_host(host);
> > + /*
> > + * If we call sdhci_runtime_suspend(), we could wakeup only if sdio
> > + * irqs are enabled. If we want to wakeup on a card detect event there
> > + * are two options:
> > + * - do not call sdhci_runtime_suspend() but save power by disabling
> > + * all clocks excepting the one for the controller interface.
> > + * - call sdhci_runtime_suspend(), save maximum power by disabling
> > + * all clocks but use a gpio for the card detect signal to have a way
> > + * to wakeup.
> > + */
> > + if (sdhci_at91_use_sdhci_runtime(host)) {
>
> I am not sure this approach is safe, particularly for cases when
> sdhci_runtime_suspend() isn't invoked.
>
> As I understand it, in those cases potentially the sdhci's IRQ handler
> may be invoked to serve even other IRQs than a card detect IRQ. Doing
> that while being runtime suspended doesn't seem like a good idea. Will
> it even work?
>
Yes it is the idea. It will allow to save some power. I don't see how I can use
runtime PM if I need to invoke sdhci_runtime_suspend_host() without modifying
sdhci layer to handle card detect irq.
I was also afraid to have some side effects but it works, at least for the
card detect case.
> > + ret = sdhci_runtime_suspend_host(host);
> > + clk_disable_unprepare(priv->hclock);
> > + }
> >
> > clk_disable_unprepare(priv->gck);
> > - clk_disable_unprepare(priv->hclock);
> > clk_disable_unprepare(priv->mainck);
> >
> > return ret;
> > @@ -84,19 +104,23 @@ static int sdhci_at91_runtime_resume(struct device *dev)
> > return ret;
> > }
> >
> > - ret = clk_prepare_enable(priv->hclock);
> > - if (ret) {
> > - dev_err(dev, "can't enable hclock\n");
> > - return ret;
> > - }
> > -
> > ret = clk_prepare_enable(priv->gck);
> > if (ret) {
> > dev_err(dev, "can't enable gck\n");
> > return ret;
> > }
> >
> > - return sdhci_runtime_resume_host(host);
> > + if (sdhci_at91_use_sdhci_runtime(host)) {
> > + ret = clk_prepare_enable(priv->hclock);
> > + if (ret) {
> > + dev_err(dev, "can't enable hclock\n");
> > + return ret;
> > + }
> > +
> > + ret = sdhci_runtime_resume_host(host);
> > + }
> > +
> > + return ret;
> > }
> > #endif /* CONFIG_PM */
Regards
Ludovic
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