[U-Boot] [PATCH] mmc: fsl_esdhc: increase data transaction timeout to 500ms

[Yangbo Lu]

The MMC spec says "It is strongly recommended for hosts to implement
more than 500ms timeout value even if the card indicates the 250ms
maximum busy length."  Even the previous value of 300ms is known to
be insufficient for some cards. So, increase the timeout to 500ms.

Signed-off-by: Yangbo Lu <yangbo.lu at nxp.com>
---
 drivers/mmc/fsl_esdhc.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/fsl_esdhc.c b/drivers/mmc/fsl_esdhc.c
index c5054d6..12820cf 100644
--- a/drivers/mmc/fsl_esdhc.c
+++ b/drivers/mmc/fsl_esdhc.c
@@ -252,8 +252,15 @@ static int esdhc_setup_data(struct mmc *mmc, struct mmc_data *data)
 	 * Rounding up to next power of 2
 	 * => timeout + 13 = log2(mmc->clock/4) + 1
 	 * => timeout + 13 = fls(mmc->clock/4)
+	 *
+	 * However, the MMC spec "It is strongly recommended for hosts to
+	 * implement more than 500ms timeout value even if the card
+	 * indicates the 250ms maximum busy length."  Even the previous
+	 * value of 300ms is known to be insufficient for some cards.
+	 * So, we use
+	 * => timeout + 13 = fls(mmc->clock/2)
 	 */
-	timeout = fls(mmc->clock/4);
+	timeout = fls(mmc->clock/2);
 	timeout -= 13;
 
 	if (timeout > 14)
-- 
2.1.0.27.g96db324