commit 61d7437ed1390 ("mmc: sdhci-acpi: Fix HS400 tuning for AMDI0040")
broke resume for HS400. When the system suspends the eMMC controller is
powered down. So on resume we need to reinitialize the controller.
amd_sdhci_host was not getting cleared, so the DLL was never re-enabled
on resume. This results in HS400 being non-functional.

This change clears the tuned_clock flag, clears the dll_enabled flag and
disables the DLL on reset.

Fixes: 61d7437ed1390 ("mmc: sdhci-acpi: Fix HS400 tuning for AMDI0040")

Signed-off-by: Raul E Rangel <rran...@chromium.org>
---
- Performed 100+ suspend/resume cycles without issue.
- Also verified tuning continues to work.

 drivers/mmc/host/sdhci-acpi.c | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/drivers/mmc/host/sdhci-acpi.c b/drivers/mmc/host/sdhci-acpi.c
index 962f074ca1742..284cba11e2795 100644
--- a/drivers/mmc/host/sdhci-acpi.c
+++ b/drivers/mmc/host/sdhci-acpi.c
@@ -551,12 +551,18 @@ static int amd_select_drive_strength(struct mmc_card 
*card,
        return MMC_SET_DRIVER_TYPE_A;
 }
 
-static void sdhci_acpi_amd_hs400_dll(struct sdhci_host *host)
+static void sdhci_acpi_amd_hs400_dll(struct sdhci_host *host, bool enable)
 {
+       struct sdhci_acpi_host *acpi_host = sdhci_priv(host);
+       struct amd_sdhci_host *amd_host = sdhci_acpi_priv(acpi_host);
+
        /* AMD Platform requires dll setting */
        sdhci_writel(host, 0x40003210, SDHCI_AMD_RESET_DLL_REGISTER);
        usleep_range(10, 20);
-       sdhci_writel(host, 0x40033210, SDHCI_AMD_RESET_DLL_REGISTER);
+       if (enable)
+               sdhci_writel(host, 0x40033210, SDHCI_AMD_RESET_DLL_REGISTER);
+
+       amd_host->dll_enabled = enable;
 }
 
 /*
@@ -596,10 +602,8 @@ static void amd_set_ios(struct mmc_host *mmc, struct 
mmc_ios *ios)
 
                /* DLL is only required for HS400 */
                if (host->timing == MMC_TIMING_MMC_HS400 &&
-                   !amd_host->dll_enabled) {
-                       sdhci_acpi_amd_hs400_dll(host);
-                       amd_host->dll_enabled = true;
-               }
+                   !amd_host->dll_enabled)
+                       sdhci_acpi_amd_hs400_dll(host, true);
        }
 }
 
@@ -620,10 +624,23 @@ static int amd_sdhci_execute_tuning(struct mmc_host *mmc, 
u32 opcode)
        return err;
 }
 
+static void amd_sdhci_reset(struct sdhci_host *host, u8 mask)
+{
+       struct sdhci_acpi_host *acpi_host = sdhci_priv(host);
+       struct amd_sdhci_host *amd_host = sdhci_acpi_priv(acpi_host);
+
+       if (mask & SDHCI_RESET_ALL) {
+               amd_host->tuned_clock = false;
+               sdhci_acpi_amd_hs400_dll(host, false);
+       }
+
+       sdhci_reset(host, mask);
+}
+
 static const struct sdhci_ops sdhci_acpi_ops_amd = {
        .set_clock      = sdhci_set_clock,
        .set_bus_width  = sdhci_set_bus_width,
-       .reset          = sdhci_reset,
+       .reset          = amd_sdhci_reset,
        .set_uhs_signaling = sdhci_set_uhs_signaling,
 };
 
-- 
2.28.0.402.g5ffc5be6b7-goog

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