sdhci: avoid changing voltage needlessly

Because of granularity issues, sometimes we told the hardware to change
to the voltage we were already at. Rework the logic so this doesn't
happen.

Signed-off-by: Pierre Ossman <pierre@ossman.eu>

2 files changed, 29 insertions, 26 deletions

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 9234be2226e7..1432a35690dd 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1005,12 +1005,34 @@ static void sdhci_set_power(struct sdhci_host *host, unsigned short power)
 {
         u8 pwr;
 
-        if (host->power == power)
+        if (power == (unsigned short)-1)
+                pwr = 0;
+        else {
+                switch (1 << power) {
+                case MMC_VDD_165_195:
+                        pwr = SDHCI_POWER_180;
+                        break;
+                case MMC_VDD_29_30:
+                case MMC_VDD_30_31:
+                        pwr = SDHCI_POWER_300;
+                        break;
+                case MMC_VDD_32_33:
+                case MMC_VDD_33_34:
+                        pwr = SDHCI_POWER_330;
+                        break;
+                default:
+                        BUG();
+                }
+        }
+
+        if (host->pwr == pwr)
                 return;
 
-        if (power == (unsigned short)-1) {
+        host->pwr = pwr;
+
+        if (pwr == 0) {
                 sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
-                goto out;
+                return;
         }
 
         /*
@@ -1020,35 +1042,16 @@ static void sdhci_set_power(struct sdhci_host *host, unsigned short power)
         if (!(host->quirks & SDHCI_QUIRK_SINGLE_POWER_WRITE))
                 sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
 
-        pwr = SDHCI_POWER_ON;
-
-        switch (1 << power) {
-        case MMC_VDD_165_195:
-                pwr |= SDHCI_POWER_180;
-                break;
-        case MMC_VDD_29_30:
-        case MMC_VDD_30_31:
-                pwr |= SDHCI_POWER_300;
-                break;
-        case MMC_VDD_32_33:
-        case MMC_VDD_33_34:
-                pwr |= SDHCI_POWER_330;
-                break;
-        default:
-                BUG();
-        }
-
         /*
          * At least the Marvell CaFe chip gets confused if we set the voltage
          * and set turn on power at the same time, so set the voltage first.
          */
         if ((host->quirks & SDHCI_QUIRK_NO_SIMULT_VDD_AND_POWER))
-                sdhci_writeb(host, pwr & ~SDHCI_POWER_ON, SDHCI_POWER_CONTROL);
+                sdhci_writeb(host, pwr, SDHCI_POWER_CONTROL);
 
-        sdhci_writeb(host, pwr, SDHCI_POWER_CONTROL);
+        pwr |= SDHCI_POWER_ON;
 
-out:
-        host->power = power;
+        sdhci_writeb(host, pwr, SDHCI_POWER_CONTROL);
 }
 
 /*****************************************************************************\
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 65c6f996bbd3..2de08349c3ca 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -255,7 +255,7 @@ struct sdhci_host {
         unsigned int            timeout_clk;    /* Timeout freq (KHz) */
 
         unsigned int            clock;          /* Current clock (MHz) */
-        unsigned short          power;          /* Current voltage */
+        u8                      pwr;            /* Current voltage */
 
         struct mmc_request      *mrq;           /* Current request */
         struct mmc_command      *cmd;           /* Current command */