[PATCH] mmc: sdhci-pci: Fix initialization of some SD cards for Intel BYT-based controllers

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

Bus power may control card power, but the full reset done by SDHCI at
initialization still may not reset the power, whereas a direct write to
SDHCI_POWER_CONTROL can. That might be needed to initialize correctly, if
the card was left powered on previously.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: stable@vger.kernel.org
---
 drivers/mmc/host/sdhci-pci-core.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
index b3caa174effe..be19785227fe 100644
--- a/drivers/mmc/host/sdhci-pci-core.c
+++ b/drivers/mmc/host/sdhci-pci-core.c
@@ -516,6 +516,7 @@ struct intel_host {
 	int	drv_strength;
 	bool	d3_retune;
 	bool	rpm_retune_ok;
+	bool	needs_pwr_off;
 	u32	glk_rx_ctrl1;
 	u32	glk_tun_val;
 	u32	active_ltr;
@@ -643,9 +644,25 @@ static int bxt_get_cd(struct mmc_host *mmc)
 static void sdhci_intel_set_power(struct sdhci_host *host, unsigned char mode,
 				  unsigned short vdd)
 {
+	struct sdhci_pci_slot *slot = sdhci_priv(host);
+	struct intel_host *intel_host = sdhci_pci_priv(slot);
 	int cntr;
 	u8 reg;
 
+	/*
+	 * Bus power may control card power, but a full reset still may not
+	 * reset the power, whereas a direct write to SDHCI_POWER_CONTROL can.
+	 * That might be needed to initialize correctly, if the card was left
+	 * powered on previously.
+	 */
+	if (intel_host->needs_pwr_off) {
+		intel_host->needs_pwr_off = false;
+		if (mode != MMC_POWER_OFF) {
+			sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
+			usleep_range(10000, 12500);
+		}
+	}
+
 	sdhci_set_power(host, mode, vdd);
 
 	if (mode == MMC_POWER_OFF)
@@ -1135,6 +1152,14 @@ static int byt_sdio_probe_slot(struct sdhci_pci_slot *slot)
 	return 0;
 }
 
+static void byt_needs_pwr_off(struct sdhci_pci_slot *slot)
+{
+	struct intel_host *intel_host = sdhci_pci_priv(slot);
+	u8 reg = sdhci_readb(slot->host, SDHCI_POWER_CONTROL);
+
+	intel_host->needs_pwr_off = reg  & SDHCI_POWER_ON;
+}
+
 static int byt_sd_probe_slot(struct sdhci_pci_slot *slot)
 {
 	byt_probe_slot(slot);
@@ -1152,6 +1177,8 @@ static int byt_sd_probe_slot(struct sdhci_pci_slot *slot)
 	    slot->chip->pdev->subsystem_device == PCI_SUBDEVICE_ID_NI_78E3)
 		slot->host->mmc->caps2 |= MMC_CAP2_AVOID_3_3V;
 
+	byt_needs_pwr_off(slot);
+
 	return 0;
 }
 
-- 
2.17.1