[PATCH 1/2] mmc: sdhci-pci: Fix S0i3 for Intel BYT-based controllers

[Adrian Hunter <adrian.hunter@intel.com>]

Tuning can leave the IP in an active state (Buffer Read Enable bit set)
which prevents the entry to low power states (i.e. S0i3). Data reset will
clear it.

Generally tuning is followed by a data transfer which will anyway sort out
the state, so it is rare that S0i3 is actually prevented.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: stable@vger.kernel.org
---
 drivers/mmc/host/sdhci-pci-core.c | 35 +++++++++++++++++++++++++++++++----
 1 file changed, 31 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
index 5296b749d661..ba725580e944 100644
--- a/drivers/mmc/host/sdhci-pci-core.c
+++ b/drivers/mmc/host/sdhci-pci-core.c
@@ -661,9 +661,36 @@ static void byt_read_dsm(struct sdhci_pci_slot *slot)
 	slot->chip->rpm_retune = intel_host->d3_retune;
 }
 
-static int byt_emmc_probe_slot(struct sdhci_pci_slot *slot)
+static int intel_execute_tuning(struct mmc_host *mmc, u32 opcode)
+{
+	int err = sdhci_execute_tuning(mmc, opcode);
+	struct sdhci_host *host = mmc_priv(mmc);
+
+	if (err)
+		return err;
+
+	/*
+	 * Tuning can leave the IP in an active state (Buffer Read Enable bit
+	 * set) which prevents the entry to low power states (i.e. S0i3). Data
+	 * reset will clear it.
+	 */
+	sdhci_reset(host, SDHCI_RESET_DATA);
+
+	return 0;
+}
+
+static void byt_probe_slot(struct sdhci_pci_slot *slot)
 {
+	struct mmc_host_ops *ops = &slot->host->mmc_host_ops;
+
 	byt_read_dsm(slot);
+
+	ops->execute_tuning = intel_execute_tuning;
+}
+
+static int byt_emmc_probe_slot(struct sdhci_pci_slot *slot)
+{
+	byt_probe_slot(slot);
 	slot->host->mmc->caps |= MMC_CAP_8_BIT_DATA | MMC_CAP_NONREMOVABLE |
 				 MMC_CAP_HW_RESET | MMC_CAP_1_8V_DDR |
 				 MMC_CAP_CMD_DURING_TFR |
@@ -786,7 +813,7 @@ static int ni_byt_sdio_probe_slot(struct sdhci_pci_slot *slot)
 {
 	int err;
 
-	byt_read_dsm(slot);
+	byt_probe_slot(slot);
 
 	err = ni_set_max_freq(slot);
 	if (err)
@@ -799,7 +826,7 @@ static int ni_byt_sdio_probe_slot(struct sdhci_pci_slot *slot)
 
 static int byt_sdio_probe_slot(struct sdhci_pci_slot *slot)
 {
-	byt_read_dsm(slot);
+	byt_probe_slot(slot);
 	slot->host->mmc->caps |= MMC_CAP_POWER_OFF_CARD | MMC_CAP_NONREMOVABLE |
 				 MMC_CAP_WAIT_WHILE_BUSY;
 	return 0;
@@ -807,7 +834,7 @@ static int byt_sdio_probe_slot(struct sdhci_pci_slot *slot)
 
 static int byt_sd_probe_slot(struct sdhci_pci_slot *slot)
 {
-	byt_read_dsm(slot);
+	byt_probe_slot(slot);
 	slot->host->mmc->caps |= MMC_CAP_WAIT_WHILE_BUSY |
 				 MMC_CAP_AGGRESSIVE_PM | MMC_CAP_CD_WAKE;
 	slot->cd_idx = 0;
-- 
1.9.1