2 files changed, 43 insertions, 0 deletions

diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index fc65475a26ee..b461b290ce25 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -925,6 +925,13 @@ static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
 
                 /* Card is an ultra-high-speed card */
                 mmc_sd_card_set_uhs(card);
+
+                /*
+                 * Since initialization is now complete, enable preset
+                 * value registers for UHS-I cards.
+                 */
+                if (host->ops->enable_preset_value)
+                        host->ops->enable_preset_value(host, true);
         } else {
                 /*
                  * Attempt to change to high-speed (if supported)
@@ -1095,6 +1102,10 @@ int mmc_attach_sd(struct mmc_host *host)
         if (err)
                 return err;
 
+        /* Disable preset value enable if already set since last time */
+        if (host->ops->enable_preset_value)
+                host->ops->enable_preset_value(host, false);
+
         err = mmc_send_app_op_cond(host, 0, &ocr);
         if (err)
                 return err;
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 8a56eacea34d..a1ab22415883 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1649,6 +1649,37 @@ out:
         return err;
 }
 
+static void sdhci_enable_preset_value(struct mmc_host *mmc, bool enable)
+{
+        struct sdhci_host *host;
+        u16 ctrl;
+        unsigned long flags;
+
+        host = mmc_priv(mmc);
+
+        /* Host Controller v3.00 defines preset value registers */
+        if (host->version < SDHCI_SPEC_300)
+                return;
+
+        spin_lock_irqsave(&host->lock, flags);
+
+        ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
+
+        /*
+         * We only enable or disable Preset Value if they are not already
+         * enabled or disabled respectively. Otherwise, we bail out.
+         */
+        if (enable && !(ctrl & SDHCI_CTRL_PRESET_VAL_ENABLE)) {
+                ctrl |= SDHCI_CTRL_PRESET_VAL_ENABLE;
+                sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
+        } else if (!enable && (ctrl & SDHCI_CTRL_PRESET_VAL_ENABLE)) {
+                ctrl &= ~SDHCI_CTRL_PRESET_VAL_ENABLE;
+                sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
+        }
+
+        spin_unlock_irqrestore(&host->lock, flags);
+}
+
 static const struct mmc_host_ops sdhci_ops = {
         .request        = sdhci_request,
         .set_ios        = sdhci_set_ios,
@@ -1656,6 +1687,7 @@ static const struct mmc_host_ops sdhci_ops = {
         .enable_sdio_irq = sdhci_enable_sdio_irq,
         .start_signal_voltage_switch    = sdhci_start_signal_voltage_switch,
         .execute_tuning                 = sdhci_execute_tuning,
+        .enable_preset_value            = sdhci_enable_preset_value,
 };
 
 /*****************************************************************************\