According to Haibo Chen [1] - the current implementation mmc_wait_dat0, the second mmc_wait_dat0() in mmc_switch_voltage() always return timeout. This causes UHS cards to not properly initialize to their highest rate, and default back for high-speed mode.
When reviewing [1] and comparing it to the linux driver, it appears that this function can be accomplished by turning off the clock, and waiting for the clock-standby bit to become active.
[1] - https://lists.denx.de/pipermail/u-boot/2021-January/438644.html
Reported-by: Tim Harvey tharvey@gateworks.com Signed-off-by: Adam Ford aford173@gmail.com
diff --git a/drivers/mmc/fsl_esdhc_imx.c b/drivers/mmc/fsl_esdhc_imx.c index 4c06361bee..e5814232a2 100644 --- a/drivers/mmc/fsl_esdhc_imx.c +++ b/drivers/mmc/fsl_esdhc_imx.c @@ -1684,9 +1684,15 @@ static int fsl_esdhc_wait_dat0(struct udevice *dev, int state, struct fsl_esdhc_priv *priv = dev_get_priv(dev); struct fsl_esdhc *regs = priv->esdhc_regs;
+ /* + * Clear the clock-enable and wait for the bit indicating it + * is in standby. + */ + esdhc_clrbits32(®s->vendorspec, VENDORSPEC_CKEN); ret = readx_poll_timeout(esdhc_read32, ®s->prsstat, tmp, - !!(tmp & PRSSTAT_DAT0) == !!state, + (tmp & PRSSTAT_SDSTB), timeout_us); + return ret; }