[PATCH 2/2] mmc: xenon: add timeout for PHY init complete

[Elad Nachman <enachman@xxxxxxxxxxx>]

From: Elad Nachman <enachman@xxxxxxxxxxx>

AC5X spec says PHY init complete bit must be polled until zero.
We see cases in which timeout can take longer than the standard
calculation on AC5X, which is expected following the spec comment above.
According to the spec, we must wait as long as it takes for that bit to
toggle on AC5X.
Cap that with 100 delay loops so we won't get stuck forever.

Signed-off-by: Elad Nachman <enachman@xxxxxxxxxxx>
---
 drivers/mmc/host/sdhci-xenon-phy.c | 31 ++++++++++++++++++++++++------
 1 file changed, 25 insertions(+), 6 deletions(-)

diff --git a/drivers/mmc/host/sdhci-xenon-phy.c b/drivers/mmc/host/sdhci-xenon-phy.c
index 4e99197b62c3..f551a9e31772 100644
--- a/drivers/mmc/host/sdhci-xenon-phy.c
+++ b/drivers/mmc/host/sdhci-xenon-phy.c
@@ -109,6 +109,8 @@
 #define XENON_EMMC_PHY_LOGIC_TIMING_ADJUST	(XENON_EMMC_PHY_REG_BASE + 0x18)
 #define XENON_LOGIC_TIMING_VALUE		0x00AA8977
 
+#define XENON_MAX_PHY_TIMEOUT_LOOPS		100
+
 /*
  * List offset of PHY registers and some special register values
  * in eMMC PHY 5.0 or eMMC PHY 5.1
@@ -244,7 +246,7 @@ static int xenon_check_stability_internal_clk(struct sdhci_host *host)
  */
 static int xenon_emmc_phy_init(struct sdhci_host *host)
 {
-	u32 reg;
+	u32 reg, retry;
 	u32 wait, clock;
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct xenon_priv *priv = sdhci_pltfm_priv(pltfm_host);
@@ -282,14 +284,31 @@ static int xenon_emmc_phy_init(struct sdhci_host *host)
 	/* get the wait time */
 	wait /= clock;
 	wait++;
-	/* wait for host eMMC PHY init completes */
-	udelay(wait);
 
-	reg = sdhci_readl(host, phy_regs->timing_adj);
-	reg &= XENON_PHY_INITIALIZAION;
+	/*
+	 * AC5X spec says bit must be polled until zero.
+	 * We see cases in which timeout can take longer
+	 * than the standard calculation on AC5X, which is
+	 * expected following the spec comment above.
+	 * According to the spec, we must wait as long as
+	 * it takes for that bit to toggle on AC5X.
+	 * Cap that with 100 delay loops so we won't get
+	 * stuck here forever:
+	 */
+
+	retry = XENON_MAX_PHY_TIMEOUT_LOOPS;
+
+	do {
+		/* wait for host eMMC PHY init completes */
+		udelay(wait);
+
+		reg = sdhci_readl(host, phy_regs->timing_adj);
+		reg &= XENON_PHY_INITIALIZAION;
+	} while (reg && retry--);
+
 	if (reg) {
 		dev_err(mmc_dev(host->mmc), "eMMC PHY init cannot complete after %d us\n",
-			wait);
+			wait * XENON_MAX_PHY_TIMEOUT_LOOPS);
 		return -ETIMEDOUT;
 	}
 
-- 
2.25.1