[PATCH] Revert "mmc: fsl_esdhc_imx: remove the 1ms delay before sending command"

[Fabio Estevam]

Removing the 1ms delay before sending command causes a regression
on imx8mq-evk where the SD card cannot be accessed.
 
Since this 1ms delay has been present since the driver introduction
in 2008, keep it to avoid regressions.

This reverts commit 9098682200e6cca4b776638a51200dafa16f50fb.

Reported-by: Ye Li <ye.li at nxp.com>
Signed-off-by: Fabio Estevam <festevam at gmail.com>
---
 drivers/mmc/fsl_esdhc_imx.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/mmc/fsl_esdhc_imx.c b/drivers/mmc/fsl_esdhc_imx.c
index e0e132698e30..a0a5c8960563 100644
--- a/drivers/mmc/fsl_esdhc_imx.c
+++ b/drivers/mmc/fsl_esdhc_imx.c
@@ -463,6 +463,13 @@ static int esdhc_send_cmd_common(struct fsl_esdhc_priv *priv, struct mmc *mmc,
 	while (esdhc_read32(&regs->prsstat) & PRSSTAT_DLA)
 		;
 
+	/* Wait at least 8 SD clock cycles before the next command */
+	/*
+	 * Note: This is way more than 8 cycles, but 1ms seems to
+	 * resolve timing issues with some cards
+	 */
+	udelay(1000);
+
 	/* Set up for a data transfer if we have one */
 	if (data) {
 		err = esdhc_setup_data(priv, mmc, data);
-- 
2.25.1