mmc: change mmc_gpio_get_cd to call non-sleep gpio

Given that mmc_gpio_get_cd can be called in softirq context (by sdhci_tasklet_card -> sdhci_card_event -> sdhci_do_get_cd -> mmc_gpio_get_cd ), it is necessary for it to use gpio_get_value instead of gpio_get_value_cansleep
Note that at present sdhci_card_event gets called both from mmc_gpio_cd_irqt and sdhci_tasklet_card, and from both it gets called immediately while the actual cd processing is debounced to 200ms later. I think that the better solution might be to move the sdhci_card_event callback into mmc_rescan and remove it from its 2 present locations. That way the cd related callbacks are aligned with the actual cd detection code. I can submit a follow-up patch with these mods if that sounds like a better way to solve this.

Signed-off-by Christian Daudt <[email protected]>

drivers/mmc/core/slot-gpio.c +1 -1

index 3242351..897b298 100644
@@ -87,7 +87,7 @@ int mmc_gpio_get_cd(struct mmc_host *host)
 	if (!ctx || !gpio_is_valid(ctx->cd_gpio))
 		return -ENOSYS;
 
-	return !gpio_get_value_cansleep(ctx->cd_gpio) ^
+	return !gpio_get_value(ctx->cd_gpio) ^
 		!!(host->caps2 & MMC_CAP2_CD_ACTIVE_HIGH);
 }
 EXPORT_SYMBOL(mmc_gpio_get_cd);

Signature · 7 lines

1.7.10.4


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Quoted 16 lines · Christian Daudt

Given that mmc_gpio_get_cd can be called in softirq context (by sdhci_tasklet_card -> sdhci_card_event -> sdhci_do_get_cd -> mmc_gpio_get_cd ), it is necessary for it to use gpio_get_value instead of gpio_get_value_cansleep
Note that at present sdhci_card_event gets called both from mmc_gpio_cd_irqt and sdhci_tasklet_card, and from both it gets called immediately while the actual cd processing is debounced to 200ms later. I think that the better solution might be to move the sdhci_card_event callback into mmc_rescan and remove it from its 2 present locations. That way the cd related callbacks are aligned with the actual cd detection code. I can submit a follow-up patch with these mods if that sounds like a better way to solve this.

Quoted 1 line

Signed-off-by Christian Daudt <[email protected]>

I don't think this is a right approach. It will Oops if the card-detect GPIO is provided by, e.g. an I2C GPIO controller. Instead the driver should be fixed to only call this function from a sleeping context.

Quoted 18 lines · Guennadi Liakhovetski

Quoted 16 lines · Christian Daudt

Given that mmc_gpio_get_cd can be called in softirq context (by sdhci_tasklet_card -> sdhci_card_event -> sdhci_do_get_cd -> mmc_gpio_get_cd ), it is necessary for it to use gpio_get_value instead of gpio_get_value_cansleep
Note that at present sdhci_card_event gets called both from mmc_gpio_cd_irqt and sdhci_tasklet_card, and from both it gets called immediately while the actual cd processing is debounced to 200ms later. I think that the better solution might be to move the sdhci_card_event callback into mmc_rescan and remove it from its 2 present locations. That way the cd related callbacks are aligned with the actual cd detection code. I can submit a follow-up patch with these mods if that sounds like a better way to solve this.

Quoted 4 lines

Quoted 1 line

Signed-off-by Christian Daudt <[email protected]>

I don't think this is a right approach. It will Oops if the card-detect GPIO is provided by, e.g. an I2C GPIO controller. Instead the driver should be fixed to only call this function from a sleeping context.

I don't think that card-detect would ever be tied to i2c but I might be wrong on that one... If there's agreement that moving sdhci_card_event into just being called from mmc_rescan is the better way to solve this, then I'll drop this patch and replace it with one that does just that.

Thanks,
csd