mmc: sdio: fix runtime PM anomalies by introducing MMC_CAP_POWER_OFF_CARD

Some board/card/host configurations are not capable of powering off the
card after boot.

To support such configurations, and to allow smoother transition to
runtime PM behavior, MMC_CAP_POWER_OFF_CARD is added, so hosts need to
explicitly indicate whether it's OK to power off their cards after boot.

SDIO core will enable runtime PM for a card only if that cap is set.
As a result, the card will be powered down after boot, and will only
be powered up again when a driver is loaded (and then it's up to the
driver to decide whether power will be kept or not).

This will prevent sdio_bus_probe() failures with setups that do not
support powering off the card.

Reported-and-tested-by: Daniel Drake <dsd@laptop.org>
Reported-and-tested-by: Arnd Hannemann <arnd@arndnet.de>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

2 files changed, 45 insertions, 25 deletions

diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
index 42a949b723b8..efef5f94ac42 100644
--- a/drivers/mmc/core/sdio.c
+++ b/drivers/mmc/core/sdio.c
@@ -547,9 +547,11 @@ static void mmc_sdio_detect(struct mmc_host *host)
         BUG_ON(!host->card);
 
         /* Make sure card is powered before detecting it */
-        err = pm_runtime_get_sync(&host->card->dev);
-        if (err < 0)
-                goto out;
+        if (host->caps & MMC_CAP_POWER_OFF_CARD) {
+                err = pm_runtime_get_sync(&host->card->dev);
+                if (err < 0)
+                        goto out;
+        }
 
         mmc_claim_host(host);
 
@@ -571,7 +573,8 @@ static void mmc_sdio_detect(struct mmc_host *host)
          * is about to show up at this point, the _sync variant is
          * desirable anyway.
          */
-        pm_runtime_put_sync(&host->card->dev);
+        if (host->caps & MMC_CAP_POWER_OFF_CARD)
+                pm_runtime_put_sync(&host->card->dev);
 
 out:
         if (err) {
@@ -728,16 +731,21 @@ int mmc_attach_sdio(struct mmc_host *host, u32 ocr)
         card = host->card;
 
         /*
-         * Let runtime PM core know our card is active
+         * Enable runtime PM only if supported by host+card+board
          */
-        err = pm_runtime_set_active(&card->dev);
-        if (err)
-                goto remove;
+        if (host->caps & MMC_CAP_POWER_OFF_CARD) {
+                /*
+                 * Let runtime PM core know our card is active
+                 */
+                err = pm_runtime_set_active(&card->dev);
+                if (err)
+                        goto remove;
 
-        /*
-         * Enable runtime PM for this card
-         */
-        pm_runtime_enable(&card->dev);
+                /*
+                 * Enable runtime PM for this card
+                 */
+                pm_runtime_enable(&card->dev);
+        }
 
         /*
          * The number of functions on the card is encoded inside
@@ -755,9 +763,10 @@ int mmc_attach_sdio(struct mmc_host *host, u32 ocr)
                         goto remove;
 
                 /*
-                 * Enable Runtime PM for this func
+                 * Enable Runtime PM for this func (if supported)
                  */
-                pm_runtime_enable(&card->sdio_func[i]->dev);
+                if (host->caps & MMC_CAP_POWER_OFF_CARD)
+                        pm_runtime_enable(&card->sdio_func[i]->dev);
         }
 
         mmc_release_host(host);
diff --git a/drivers/mmc/core/sdio_bus.c b/drivers/mmc/core/sdio_bus.c
index 2716c7ab6bbf..203da443e339 100644
--- a/drivers/mmc/core/sdio_bus.c
+++ b/drivers/mmc/core/sdio_bus.c
@@ -17,6 +17,7 @@
 #include <linux/pm_runtime.h>
 
 #include <linux/mmc/card.h>
+#include <linux/mmc/host.h>
 #include <linux/mmc/sdio_func.h>
 
 #include "sdio_cis.h"
@@ -132,9 +133,11 @@ static int sdio_bus_probe(struct device *dev)
          * it should call pm_runtime_put_noidle() in its probe routine and
          * pm_runtime_get_noresume() in its remove routine.
          */
-        ret = pm_runtime_get_sync(dev);
-        if (ret < 0)
-                goto out;
+        if (func->card->host->caps & MMC_CAP_POWER_OFF_CARD) {
+                ret = pm_runtime_get_sync(dev);
+                if (ret < 0)
+                        goto out;
+        }
 
         /* Set the default block size so the driver is sure it's something
          * sensible. */
@@ -151,7 +154,8 @@ static int sdio_bus_probe(struct device *dev)
         return 0;
 
 disable_runtimepm:
-        pm_runtime_put_noidle(dev);
+        if (func->card->host->caps & MMC_CAP_POWER_OFF_CARD)
+                pm_runtime_put_noidle(dev);
 out:
         return ret;
 }
@@ -160,12 +164,14 @@ static int sdio_bus_remove(struct device *dev)
 {
         struct sdio_driver *drv = to_sdio_driver(dev->driver);
         struct sdio_func *func = dev_to_sdio_func(dev);
-        int ret;
+        int ret = 0;
 
         /* Make sure card is powered before invoking ->remove() */
-        ret = pm_runtime_get_sync(dev);
-        if (ret < 0)
-                goto out;
+        if (func->card->host->caps & MMC_CAP_POWER_OFF_CARD) {
+                ret = pm_runtime_get_sync(dev);
+                if (ret < 0)
+                        goto out;
+        }
 
         drv->remove(func);
 
@@ -178,10 +184,12 @@ static int sdio_bus_remove(struct device *dev)
         }
 
         /* First, undo the increment made directly above */
-        pm_runtime_put_noidle(dev);
+        if (func->card->host->caps & MMC_CAP_POWER_OFF_CARD)
+                pm_runtime_put_noidle(dev);
 
         /* Then undo the runtime PM settings in sdio_bus_probe() */
-        pm_runtime_put_noidle(dev);
+        if (func->card->host->caps & MMC_CAP_POWER_OFF_CARD)
+                pm_runtime_put_noidle(dev);
 
 out:
         return ret;
@@ -191,6 +199,8 @@ out:
 
 static int sdio_bus_pm_prepare(struct device *dev)
 {
+        struct sdio_func *func = dev_to_sdio_func(dev);
+
         /*
          * Resume an SDIO device which was suspended at run time at this
          * point, in order to allow standard SDIO suspend/resume paths
@@ -212,7 +222,8 @@ static int sdio_bus_pm_prepare(struct device *dev)
          * since there is little point in failing system suspend if a
          * device can't be resumed.
          */
-        pm_runtime_resume(dev);
+        if (func->card->host->caps & MMC_CAP_POWER_OFF_CARD)
+                pm_runtime_resume(dev);
 
         return 0;
 }