Re: [PATCH 2/2] mmc: core: Add tunable delay before detecting card after card is inserted

[Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>]

Hi Ulf,

On 2018/4/12 14:32, Ulf Hansson wrote:
> On 12 April 2018 at 03:20, Shawn Lin <shawn.lin@xxxxxxxxxxxxxx> wrote:
> > Allow to use tunable delay before detecting card after card is inserted
> > either from firmware, or argument passing to mmc_gpiod_request_cd(). The
> > default value is 200ms as before, if cd-delay-ms isn't present but using
> > mmc_gpiod_request_cd() to request slot-gpio interrupt.
>
> Exactly why doesn't the 200 ms delay works?
>
> It seems like the proper method is instead to use a gpio debouncing
> time. mmc-slot-gpio already deals with that, but we are defaulting to
> use zero as debounce period, when mmc_gpiod_request_cd() is called
> from mmc_of_parse().

I noticed we was defauting to use zero there, but that's no key point
for me to use another delay. That being said not all platforms support
gpio debounce, then gpiod_set_debounce() just returns -ENOTSUPP. So
mmc_of_parse uses zero debounce period for mmc_gpiod_request_cd() is
fine,otherwise mmc_gpiod_request_cd() should be improved to deal with
failure of gpiod_set_debounce().

How about:

mmc_of_parse()
   --> mmc_gpiod_request_cd(200ms debounce peroid) {

	...

     	if (debounce)
          	gpiod_set_debounce(desc, debounce);

        if (gpio_invert)
                *gpio_invert = !gpiod_is_active_low(desc);

        ctx->override_cd_active_level = override_active_level;
        ctx->cd_gpio = desc;
	/* Software debounce */
        ctx->cd_delay_ms =  max_t(unsigned int, debounce, 200);
      }


> Kind regards
> Uffe
>
> > Signed-off-by: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>
> > ---
> >
> >   drivers/mmc/core/host.c           |  7 +++++--
> >   drivers/mmc/core/slot-gpio.c      | 11 +++++++++--
> >   drivers/mmc/host/davinci_mmc.c    |  2 +-
> >   drivers/mmc/host/mmci.c           |  2 +-
> >   drivers/mmc/host/sdhci-acpi.c     |  2 +-
> >   drivers/mmc/host/sdhci-pci-core.c |  3 ++-
> >   include/linux/mmc/slot-gpio.h     |  3 ++-
> >   7 files changed, 21 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
> > index 64b03d6..cb8babc 100644
> > --- a/drivers/mmc/core/host.c
> > +++ b/drivers/mmc/core/host.c
> > @@ -179,7 +179,7 @@ static void mmc_retune_timer(struct timer_list *t)
> >   int mmc_of_parse(struct mmc_host *host)
> >   {
> >          struct device *dev = host->parent;
> > -       u32 bus_width, drv_type;
> > +       u32 bus_width, drv_type, cd_delay_ms;
> >          int ret;
> >          bool cd_cap_invert, cd_gpio_invert = false;
> >          bool ro_cap_invert, ro_gpio_invert = false;
> > @@ -230,11 +230,14 @@ int mmc_of_parse(struct mmc_host *host)
> >          } else {
> >                  cd_cap_invert = device_property_read_bool(dev, "cd-inverted");
> >
> > +               if (device_property_read_u32(dev, "cd-delay-ms", &cd_delay_ms))
> > +                       cd_delay_ms = 200;
> > +
> >                  if (device_property_read_bool(dev, "broken-cd"))
> >                          host->caps |= MMC_CAP_NEEDS_POLL;
> >
> >                  ret = mmc_gpiod_request_cd(host, "cd", 0, true,
> > -                                          0, &cd_gpio_invert);
> > +                                          0, &cd_gpio_invert, cd_delay_ms);
> >                  if (!ret)
> >                          dev_info(host->parent, "Got CD GPIO\n");
> >                  else if (ret != -ENOENT && ret != -ENOSYS)
> > diff --git a/drivers/mmc/core/slot-gpio.c b/drivers/mmc/core/slot-gpio.c
> > index 31f7dbb..baa6e8d 100644
> > --- a/drivers/mmc/core/slot-gpio.c
> > +++ b/drivers/mmc/core/slot-gpio.c
> > @@ -28,15 +28,17 @@ struct mmc_gpio {
> >          irqreturn_t (*cd_gpio_isr)(int irq, void *dev_id);
> >          char *ro_label;
> >          char cd_label[0];
> > +       u32 cd_delay_ms;
> >   };
> >
> >   static irqreturn_t mmc_gpio_cd_irqt(int irq, void *dev_id)
> >   {
> >          /* Schedule a card detection after a debounce timeout */
> >          struct mmc_host *host = dev_id;
> > +       struct mmc_gpio *ctx = host->slot.handler_priv;
> >
> >          host->trigger_card_event = true;
> > -       mmc_detect_change(host, msecs_to_jiffies(200));
> > +       mmc_detect_change(host, msecs_to_jiffies(ctx->cd_delay_ms));
> >
> >          return IRQ_HANDLED;
> >   }
> > @@ -49,6 +51,7 @@ int mmc_gpio_alloc(struct mmc_host *host)
> >
> >          if (ctx) {
> >                  ctx->ro_label = ctx->cd_label + len;
> > +               ctx->cd_delay_ms = 200;
> >                  snprintf(ctx->cd_label, len, "%s cd", dev_name(host->parent));
> >                  snprintf(ctx->ro_label, len, "%s ro", dev_name(host->parent));
> >                  host->slot.handler_priv = ctx;
> > @@ -239,6 +242,8 @@ int mmc_gpio_request_cd(struct mmc_host *host, unsigned int gpio,
> >    * @debounce: debounce time in microseconds
> >    * @gpio_invert: will return whether the GPIO line is inverted or not, set
> >    * to NULL to ignore
> > + * @cd_delay_ms: delay time in ms before detecting card after card insert
> > + * event
> >    *
> >    * Use this function in place of mmc_gpio_request_cd() to use the GPIO
> >    * descriptor API.  Note that it must be called prior to mmc_add_host()
> > @@ -248,7 +253,8 @@ int mmc_gpio_request_cd(struct mmc_host *host, unsigned int gpio,
> >    */
> >   int mmc_gpiod_request_cd(struct mmc_host *host, const char *con_id,
> >                           unsigned int idx, bool override_active_level,
> > -                        unsigned int debounce, bool *gpio_invert)
> > +                        unsigned int debounce, bool *gpio_invert,
> > +                        u32 cd_delay_ms)
> >   {
> >          struct mmc_gpio *ctx = host->slot.handler_priv;
> >          struct gpio_desc *desc;
> > @@ -269,6 +275,7 @@ int mmc_gpiod_request_cd(struct mmc_host *host, const char *con_id,
> >
> >          ctx->override_cd_active_level = override_active_level;
> >          ctx->cd_gpio = desc;
> > +       ctx->cd_delay_ms = cd_delay_ms;
> >
> >          return 0;
> >   }
> > diff --git a/drivers/mmc/host/davinci_mmc.c b/drivers/mmc/host/davinci_mmc.c
> > index 8e36317..fcff397 100644
> > --- a/drivers/mmc/host/davinci_mmc.c
> > +++ b/drivers/mmc/host/davinci_mmc.c
> > @@ -1187,7 +1187,7 @@ static int mmc_davinci_parse_pdata(struct mmc_host *mmc)
> >                  mmc->caps |= pdata->caps;
> >
> >          /* Register a cd gpio, if there is not one, enable polling */
> > -       ret = mmc_gpiod_request_cd(mmc, "cd", 0, false, 0, NULL);
> > +       ret = mmc_gpiod_request_cd(mmc, "cd", 0, false, 0, NULL, 200);
> >          if (ret == -EPROBE_DEFER)
> >                  return ret;
> >          else if (ret)
> > diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
> > index 70b0df8..0771c4f 100644
> > --- a/drivers/mmc/host/mmci.c
> > +++ b/drivers/mmc/host/mmci.c
> > @@ -1827,7 +1827,7 @@ static int mmci_probe(struct amba_device *dev,
> >           * silently of these do not exist and proceed to try platform data
> >           */
> >          if (!np) {
> > -               ret = mmc_gpiod_request_cd(mmc, "cd", 0, false, 0, NULL);
> > +               ret = mmc_gpiod_request_cd(mmc, "cd", 0, false, 0, NULL, 200);
> >                  if (ret < 0) {
> >                          if (ret == -EPROBE_DEFER)
> >                                  goto clk_disable;
> > diff --git a/drivers/mmc/host/sdhci-acpi.c b/drivers/mmc/host/sdhci-acpi.c
> > index 32321bd..4157a29 100644
> > --- a/drivers/mmc/host/sdhci-acpi.c
> > +++ b/drivers/mmc/host/sdhci-acpi.c
> > @@ -718,7 +718,7 @@ static int sdhci_acpi_probe(struct platform_device *pdev)
> >          if (sdhci_acpi_flag(c, SDHCI_ACPI_SD_CD)) {
> >                  bool v = sdhci_acpi_flag(c, SDHCI_ACPI_SD_CD_OVERRIDE_LEVEL);
> >
> > -               err = mmc_gpiod_request_cd(host->mmc, NULL, 0, v, 0, NULL);
> > +               err = mmc_gpiod_request_cd(host->mmc, NULL, 0, v, 0, NULL, 200);
> >                  if (err) {
> >                          if (err == -EPROBE_DEFER)
> >                                  goto err_free;
> > diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
> > index 787434e..7842a67 100644
> > --- a/drivers/mmc/host/sdhci-pci-core.c
> > +++ b/drivers/mmc/host/sdhci-pci-core.c
> > @@ -1715,7 +1715,8 @@ static struct sdhci_pci_slot *sdhci_pci_probe_slot(
> >
> >          if (slot->cd_idx >= 0) {
> >                  ret = mmc_gpiod_request_cd(host->mmc, NULL, slot->cd_idx,
> > -                                          slot->cd_override_level, 0, NULL);
> > +                                          slot->cd_override_level, 0, NULL,
> > +                                          200);
> >                  if (ret == -EPROBE_DEFER)
> >                          goto remove;
> >
> > diff --git a/include/linux/mmc/slot-gpio.h b/include/linux/mmc/slot-gpio.h
> > index 06607c5..b13f3a9 100644
> > --- a/include/linux/mmc/slot-gpio.h
> > +++ b/include/linux/mmc/slot-gpio.h
> > @@ -25,7 +25,8 @@ int mmc_gpio_request_cd(struct mmc_host *host, unsigned int gpio,
> >
> >   int mmc_gpiod_request_cd(struct mmc_host *host, const char *con_id,
> >                           unsigned int idx, bool override_active_level,
> > -                        unsigned int debounce, bool *gpio_invert);
> > +                        unsigned int debounce, bool *gpio_invert,
> > +                        u32 cd_delay);
> >   int mmc_gpiod_request_ro(struct mmc_host *host, const char *con_id,
> >                           unsigned int idx, bool override_active_level,
> >                           unsigned int debounce, bool *gpio_invert);
> > --
> > 1.9.1
> >
> >
> > --
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