1 files changed, 20 insertions, 4 deletions

diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index 5afac2081185..41bfb5dfe6ff 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -15,6 +15,7 @@
 #include <linux/mmc/host.h>
 #include <linux/mmc/card.h>
 #include <linux/mmc/mmc.h>
+#include <linux/mmc/sd.h>
 
 #include "core.h"
 #include "sysfs.h"
@@ -192,6 +193,16 @@ static int mmc_read_switch(struct mmc_card *card)
         int err;
         u8 *status;
 
+        if (card->scr.sda_vsn < SCR_SPEC_VER_1)
+                return MMC_ERR_NONE;
+
+        if (!(card->csd.cmdclass & CCC_SWITCH)) {
+                printk(KERN_WARNING "%s: card lacks mandatory switch "
+                        "function, performance might suffer.\n",
+                        mmc_hostname(card->host));
+                return MMC_ERR_NONE;
+        }
+
         err = MMC_ERR_FAILED;
 
         status = kmalloc(64, GFP_KERNEL);
@@ -204,10 +215,9 @@ static int mmc_read_switch(struct mmc_card *card)
 
         err = mmc_sd_switch(card, 0, 0, 1, status);
         if (err != MMC_ERR_NONE) {
-                /*
-                 * Card not supporting high-speed will ignore the
-                 * command.
-                 */
+                printk(KERN_WARNING "%s: problem reading switch "
+                        "capabilities, performance might suffer.\n",
+                        mmc_hostname(card->host));
                 err = MMC_ERR_NONE;
                 goto out;
         }
@@ -229,6 +239,12 @@ static int mmc_switch_hs(struct mmc_card *card)
         int err;
         u8 *status;
 
+        if (card->scr.sda_vsn < SCR_SPEC_VER_1)
+                return MMC_ERR_NONE;
+
+        if (!(card->csd.cmdclass & CCC_SWITCH))
+                return MMC_ERR_NONE;
+
         if (!(card->host->caps & MMC_CAP_SD_HIGHSPEED))
                 return MMC_ERR_NONE;