mmc: core: enable CMD19 tuning for DDR50 mode

As SD Specifications Part1 Physical Layer Specification Version
3.01 says, CMD19 tuning is available for unlocked cards in transfer
state of 1.8V signaling mode. The small difference between v3.00
and 3.01 spec means that CMD19 tuning is also available for DDR50
mode.

Signed-off-by: Weijun Yang <york.yang@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index e28ebf3c1c4bc683955ae3d3898fa33f40c88da8..e124db0fc1780b2b2225c8f7a3f2f7d34cf35afd 100644 (file)
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -626,9 +626,25 @@ static int mmc_sd_init_uhs_card(struct mmc_card *card)
         * SDR104 mode SD-cards. Note that tuning is mandatory for SDR104.
         */
        if (!mmc_host_is_spi(card->host) &&
-           (card->sd_bus_speed == UHS_SDR50_BUS_SPEED ||
-            card->sd_bus_speed == UHS_SDR104_BUS_SPEED))
+               (card->sd_bus_speed == UHS_SDR50_BUS_SPEED ||
+                card->sd_bus_speed == UHS_DDR50_BUS_SPEED ||
+                card->sd_bus_speed == UHS_SDR104_BUS_SPEED)) {
                err = mmc_execute_tuning(card);
+
+               /*
+                * As SD Specifications Part1 Physical Layer Specification
+                * Version 3.01 says, CMD19 tuning is available for unlocked
+                * cards in transfer state of 1.8V signaling mode. The small
+                * difference between v3.00 and 3.01 spec means that CMD19
+                * tuning is also available for DDR50 mode.
+                */
+               if (err && card->sd_bus_speed == UHS_DDR50_BUS_SPEED) {
+                       pr_warn("%s: ddr50 tuning failed\n",
+                               mmc_hostname(card->host));
+                       err = 0;
+               }
+       }
+
 out:
        kfree(status);