mmc: sdhci-msm: Optionally wait for signal level changes

Not all instances of the SDCC core supports changing signal voltage and
as such will not generate a power interrupt when the software attempts
to change the voltage. This results in probing the eMMC on some devices
to take over 2 minutes.

Check that the SWITCHABLE_SIGNALING_VOLTAGE bit in MCI_GENERICS is set
before waiting for the power interrupt.

Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Vijay Viswanath <vviswana@codeaurora.org>
Fixes: c0309b3803fe ("mmc: sdhci-msm: Add sdhci msm register write APIs which wait for pwr irq")
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Tested-by: Luca Weiss <luca@z3ntu.xyz>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
index 3fb7d2eec93f4d72d63dbc5983e47a2b8dbc710d..c283291db705238dab53ee0104808a198aa4288e 100644 (file)
--- a/drivers/mmc/host/sdhci-msm.c
+++ b/drivers/mmc/host/sdhci-msm.c
@@ -29,6 +29,9 @@
 #define CORE_VERSION_MAJOR_MASK                (0xf << CORE_VERSION_MAJOR_SHIFT)
 #define CORE_VERSION_MINOR_MASK                0xff
 
+#define CORE_MCI_GENERICS              0x70
+#define SWITCHABLE_SIGNALING_VOLTAGE   BIT(29)
+
 #define CORE_HC_MODE           0x78
 #define HC_MODE_EN             0x1
 #define CORE_POWER             0x0
@@ -1028,11 +1031,22 @@ static void sdhci_msm_check_power_status(struct sdhci_host *host, u32 req_type)
        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
        struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
        bool done = false;
+       u32 val;
 
        pr_debug("%s: %s: request %d curr_pwr_state %x curr_io_level %x\n",
                        mmc_hostname(host->mmc), __func__, req_type,
                        msm_host->curr_pwr_state, msm_host->curr_io_level);
 
+       /*
+        * The power interrupt will not be generated for signal voltage
+        * switches if SWITCHABLE_SIGNALING_VOLTAGE in MCI_GENERICS is not set.
+        */
+       val = readl(msm_host->core_mem + CORE_MCI_GENERICS);
+       if ((req_type & REQ_IO_HIGH || req_type & REQ_IO_LOW) &&
+           !(val & SWITCHABLE_SIGNALING_VOLTAGE)) {
+               return;
+       }
+
        /*
         * The IRQ for request type IO High/LOW will be generated when -
         * there is a state change in 1.8V enable bit (bit 3) of