MMC: Fix handling of low-voltage cards

Fix handling of low voltage MMC cards.

The latest MMC and SD specs both agree that support for
low-voltage operations is indicated by bit 7 in the OCR.
The MMC spec states that the low voltage range is
1.65-1.95V while the SD spec leaves the actual voltage
range undefined - meaning that there is still no such
thing as a low voltage SD card.

However, an old Sandisk spec implied that bits 7.0
represented voltages below 2.0V in 1V or 0.5V increments,
and the code was accordingly written with that expectation.

This confusion meant that host drivers attempting to support
the typical low voltage (1.8V) would set the wrong bits in
the host OCR mask (usually bits 5 and/or 6) resulting in the
the low voltage mode never being used.

This change corrects the low voltage range and adds sanity
checks on the reserved bits (0-6) and for SD cards that
claim to support low-voltage operations.

Signed-off-by: Philip Langdale <philipl@overt.org>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

1 files changed, 1 insertions, 8 deletions

diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 5a66d8a2bf1..b1350dfd3e9 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -65,14 +65,7 @@ struct mmc_host {
         unsigned int            f_max;
         u32                     ocr_avail;
 
-#define MMC_VDD_145_150         0x00000001      /* VDD voltage 1.45 - 1.50 */
-#define MMC_VDD_150_155         0x00000002      /* VDD voltage 1.50 - 1.55 */
-#define MMC_VDD_155_160         0x00000004      /* VDD voltage 1.55 - 1.60 */
-#define MMC_VDD_160_165         0x00000008      /* VDD voltage 1.60 - 1.65 */
-#define MMC_VDD_165_170         0x00000010      /* VDD voltage 1.65 - 1.70 */
-#define MMC_VDD_17_18           0x00000020      /* VDD voltage 1.7 - 1.8 */
-#define MMC_VDD_18_19           0x00000040      /* VDD voltage 1.8 - 1.9 */
-#define MMC_VDD_19_20           0x00000080      /* VDD voltage 1.9 - 2.0 */
+#define MMC_VDD_165_195         0x00000080      /* VDD voltage 1.65 - 1.95 */
 #define MMC_VDD_20_21           0x00000100      /* VDD voltage 2.0 ~ 2.1 */
 #define MMC_VDD_21_22           0x00000200      /* VDD voltage 2.1 ~ 2.2 */
 #define MMC_VDD_22_23           0x00000400      /* VDD voltage 2.2 ~ 2.3 */