mmc: core: add the capability for broken voltage
Jaehoon Chung [Mon, 16 Jan 2012 08:49:01 +0000 (17:49 +0900)]
There is an understood mismatch between the voltage the host controller is
set to and the voltage supplied to the card by a fixed voltage regulator.
Teaching the driver to accept the mismatch is overly complicated.  Instead
just accept the regulator's voltage.

This patch adds MMC_CAP2_BROKEN_VOLTAGE.

If the voltage didn't satisfy between min_uV and max_uV, try to change
the voltage in core.c.  When changing the voltage, maybe use
regulator_set_voltage().

In regulator_set_voltage(), check the below condition.

/* sanity check */
if (!rdev->desc->ops->set_voltage &&
    !rdev->desc->ops->set_voltage_sel) {
ret = -EINVAL;
goto out;
}

If some board should use the fixed-regulator, always return -EINVAL.
Then, eMMC didn't initialize always.

So if use a fixed-regulator, we need to add the MMC_CAP2_BROKEN_VOLTAGE.

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/core/core.c
include/linux/mmc/host.h

index b3063b7..1866155 100644 (file)
@@ -1131,6 +1131,10 @@ int mmc_regulator_set_ocr(struct mmc_host *mmc,
                 * might not allow this operation
                 */
                voltage = regulator_get_voltage(supply);
+
+               if (mmc->caps2 & MMC_CAP2_BROKEN_VOLTAGE)
+                       min_uV = max_uV = voltage;
+
                if (voltage < 0)
                        result = voltage;
                else if (voltage < min_uV || voltage > max_uV)
index 73e5ee8..ee2b036 100644 (file)
@@ -257,6 +257,7 @@ struct mmc_host {
 #define MMC_CAP2_HS200_1_2V_SDR        (1 << 6)        /* can support */
 #define MMC_CAP2_HS200         (MMC_CAP2_HS200_1_8V_SDR | \
                                 MMC_CAP2_HS200_1_2V_SDR)
+#define MMC_CAP2_BROKEN_VOLTAGE        (1 << 7)        /* Use the broken voltage */
 
        mmc_pm_flag_t           pm_caps;        /* supported pm features */
        unsigned int        power_notify_type;