mmc: don't call switch on old cards
Make sure we don't call the switch function on cards too old to
support it. They should just ignore it, but some have been reported
to lock up instead.
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index 5afac20..41bfb5df 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 @@
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 @@
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 @@
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;