mmc: sd: Add new CONFIG_MMC_PARANOID_SD_INIT for enabling retries during SD detection

Signed-off-by: San Mehat <san@google.com>

diff --git a/drivers/mmc/core/Kconfig b/drivers/mmc/core/Kconfig
index ef10387..1972b00 100644 (file)
--- a/drivers/mmc/core/Kconfig
+++ b/drivers/mmc/core/Kconfig
@@ -27,3 +27,11 @@ config MMC_CLKGATE
          support handling this in order for it to be of any use.
 
          If unsure, say N.
+
+config MMC_PARANOID_SD_INIT
+       bool "Enable paranoid SD card initialization (EXPERIMENTAL)"
+       help
+         If you say Y here, the MMC layer will be extra paranoid
+         about re-trying SD init requests. This can be a useful
+         work-around for buggy controllers and hardware. Enable
+         if you are experiencing issues with SD detection.

diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index ff27741..fe75780 100644 (file)
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -684,6 +684,9 @@ struct device_type sd_type = {
 int mmc_sd_get_cid(struct mmc_host *host, u32 ocr, u32 *cid, u32 *rocr)
 {
        int err;
+#ifdef CONFIG_MMC_PARANOID_SD_INIT
+       int retries;
+#endif
 
        /*
         * Since we're changing the OCR value, we seem to
@@ -790,7 +793,26 @@ int mmc_sd_setup_card(struct mmc_host *host, struct mmc_card *card,
                /*
                 * Fetch switch information from card.
                 */
+#ifdef CONFIG_MMC_PARANOID_SD_INIT
+               for (retries = 1; retries <= 3; retries++) {
+                       err = mmc_read_switch(card);
+                       if (!err) {
+                               if (retries > 1) {
+                                       printk(KERN_WARNING
+                                              "%s: recovered\n", 
+                                              mmc_hostname(host));
+                               }
+                               break;
+                       } else {
+                               printk(KERN_WARNING
+                                      "%s: read switch failed (attempt %d)\n",
+                                      mmc_hostname(host), retries);
+                       }
+               }
+#else
                err = mmc_read_switch(card);
+#endif
+
                if (err)
                        return err;
        }