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 ab37a6d9d32a046d7318b3a89a6358c8456b5ef9..103be88956762ce1b2f591e48d2498332e1a9944 100644 (file)
--- a/drivers/mmc/core/Kconfig
+++ b/drivers/mmc/core/Kconfig
@@ -14,3 +14,11 @@ config MMC_UNSAFE_RESUME
          This option is usually just for embedded systems which use
          a MMC/SD card for rootfs. Most people should say N here.
 
+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 10b2a4d20f5a1a6b270592d6b048514126bda96a..2d089e672c6bd27061398088d34fb5f31c6c9f06 100644 (file)
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -336,7 +336,9 @@ static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
        int err;
        u32 cid[4];
        unsigned int max_dtr;
-
+#ifdef CONFIG_MMC_PARANOID_SD_INIT
+       int retries;
+#endif
        BUG_ON(!host);
        WARN_ON(!host->claimed);
 
@@ -439,11 +441,29 @@ static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
                err = mmc_decode_scr(card);
                if (err < 0)
                        goto free_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)
                        goto free_card;
        }