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_SIGNAL_VOLTAGE bit in MCI_GENERICS is set
before waiting for the power interrupt.

Cc: Sahitya Tummala <stumm...@codeaurora.org>
Cc: Vijay Viswanath <vvisw...@codeaurora.org>
Fixes: c0309b3803fe ("mmc: sdhci-msm: Add sdhci msm register write APIs which 
wait for pwr irq")
Signed-off-by: Bjorn Andersson <bjorn.anders...@linaro.org>
---

The offending patch is part of your v4.15 pull request, so please pick
this up for the -rcs.

 drivers/mmc/host/sdhci-msm.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
index 3fb7d2eec93f..8f2dda73e6b4 100644
--- 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 SWICHABLE_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 SWICHABLE_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 & SWICHABLE_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
-- 
2.15.0

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