[U-Boot] [PATCH] mmc: fsl_esdhc: Avoid infinite loop in esdhc_send_cmd_common()

[Fabio Estevam]

The following hang is observed on a Hummingboard 2 MicroSOM
i2eX iMX6D - rev 1.3 with no eMMC populated on board:

U-Boot SPL 2018.11+gf6206f8587 (Nov 16 2018 - 00:56:34 +0000)
Trying to boot from MMC1

U-Boot 2018.11+gf6206f8587 (Nov 16 2018 - 00:56:34 +0000)

CPU:   Freescale i.MX6D rev1.5 996 MHz (running at 792 MHz)
CPU:   Extended Commercial temperature grade (-20C to 105C) at 33C
Reset cause: POR
Board: MX6 HummingBoard2
DRAM:  1 GiB
MMC:   FSL_SDHC: 0, FSL_SDHC: 1
Loading Environment from MMC... *** Warning - bad CRC, using default environment

No panel detected: default to HDMI
Display: HDMI (1024x768)
In:    serial
Out:   serial
Err:   serial
---> hangs

which is caused by the following infinite loop inside esdhc_send_cmd_common()

	while (!(esdhc_read32(&regs->irqstat) & flags))
		;

Instead of looping forever, provide an exit path so that a timeout
error can be propagated in the case irqstat does not report
any interrupts, which may happen when no eMMC is populated on
board.

Reported-by: Ricardo Salveti <rsalveti at rsalveti.net>
Signed-off-by: Fabio Estevam <festevam at gmail.com>
---
 drivers/mmc/fsl_esdhc.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/fsl_esdhc.c b/drivers/mmc/fsl_esdhc.c
index 3cdfa7f..7c17b79 100644
--- a/drivers/mmc/fsl_esdhc.c
+++ b/drivers/mmc/fsl_esdhc.c
@@ -396,6 +396,7 @@ static int esdhc_send_cmd_common(struct fsl_esdhc_priv *priv, struct mmc *mmc,
 	uint	irqstat;
 	u32	flags = IRQSTAT_CC | IRQSTAT_CTOE;
 	struct fsl_esdhc *regs = priv->esdhc_regs;
+	unsigned long start;
 
 #ifdef CONFIG_SYS_FSL_ERRATUM_ESDHC111
 	if (cmd->cmdidx == MMC_CMD_STOP_TRANSMISSION)
@@ -453,8 +454,11 @@ static int esdhc_send_cmd_common(struct fsl_esdhc_priv *priv, struct mmc *mmc,
 		flags = IRQSTAT_BRR;
 
 	/* Wait for the command to complete */
-	while (!(esdhc_read32(&regs->irqstat) & flags))
-		;
+	start = get_timer(0);
+	while (!(esdhc_read32(&regs->irqstat) & flags)) {
+		if (get_timer(start) > 1000)
+			return -ETIMEDOUT;
+	}
 
 	irqstat = esdhc_read32(&regs->irqstat);
 
-- 
2.7.4