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.
> .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?
> + 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 */
>
> --
> 2.7.0
>
Kind regards
Uffe
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