[PATCH v2] mmc: host: sdhci-sprd: Fix the incorrect soft reset operation when runtime resuming

[Baolin Wang <baolin.wang@linaro.org>]

In sdhci_runtime_resume_host() function, we will always do software reset
for all, which will cause Spreadtrum host controller work abnormally after
resuming.

Thus for Spreadtrum platform that do not power down the SD/eMMC card during
runtime suspend, we should not do software reset for all. To fix this
issue, adding a specific reset operation that add one condition to validate
the MMC_CAP_AGGRESSIVE_PM to decide if we can do software reset for all or
just reset command and data lines.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
Changes from v1:
 - Add a specific reset operation instead of changing the core to avoid
 affecting other hardware.
---
 drivers/mmc/host/sdhci-sprd.c |   38 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci-sprd.c b/drivers/mmc/host/sdhci-sprd.c
index 603a5d9..174b566 100644
--- a/drivers/mmc/host/sdhci-sprd.c
+++ b/drivers/mmc/host/sdhci-sprd.c
@@ -373,6 +373,42 @@ static unsigned int sdhci_sprd_get_max_timeout_count(struct sdhci_host *host)
 	return 1 << 31;
 }
 
+static void sdhci_sprd_reset(struct sdhci_host *host, u8 mask)
+{
+	struct mmc_host *mmc = host->mmc;
+	ktime_t timeout;
+
+	/*
+	 * When try to reset controller after runtime suspend, we should not
+	 * reset for all if the SD/eMMC card is not power down, just reset
+	 * command and data lines instead. Otherwise will meet some strange
+	 * behaviors for Spreadtrum host controller.
+	 */
+	if (host->runtime_suspended && (mask & SDHCI_RESET_ALL) &&
+	    !(mmc->caps & MMC_CAP_AGGRESSIVE_PM))
+		mask = SDHCI_RESET_CMD | SDHCI_RESET_DATA;
+
+	sdhci_writeb(host, mask, SDHCI_SOFTWARE_RESET);
+
+	/* Wait max 100 ms */
+	timeout = ktime_add_ms(ktime_get(), 100);
+
+	/* hw clears the bit when it's done */
+	while (1) {
+		bool timedout = ktime_after(ktime_get(), timeout);
+
+		if (!(sdhci_readb(host, SDHCI_SOFTWARE_RESET) & mask))
+			break;
+		if (timedout) {
+			pr_err("%s: Reset 0x%x never completed.\n",
+				mmc_hostname(host->mmc), (int)mask);
+			sdhci_dumpregs(host);
+			return;
+		}
+		udelay(10);
+	}
+}
+
 static struct sdhci_ops sdhci_sprd_ops = {
 	.read_l = sdhci_sprd_readl,
 	.write_l = sdhci_sprd_writel,
@@ -381,7 +417,7 @@ static unsigned int sdhci_sprd_get_max_timeout_count(struct sdhci_host *host)
 	.get_max_clock = sdhci_sprd_get_max_clock,
 	.get_min_clock = sdhci_sprd_get_min_clock,
 	.set_bus_width = sdhci_set_bus_width,
-	.reset = sdhci_reset,
+	.reset = sdhci_sprd_reset,
 	.set_uhs_signaling = sdhci_sprd_set_uhs_signaling,
 	.hw_reset = sdhci_sprd_hw_reset,
 	.get_max_timeout_count = sdhci_sprd_get_max_timeout_count,
-- 
1.7.9.5