mmc: mmci: stm32: clear DLYB_CR after sending tuning command

During test campaign, and especially after several unbind/bind sequences,
it has been seen that the SD-card on SDMMC1 thread could freeze.
The freeze always appear on a CMD23 following a CMD19.
Checking SDMMC internal registers shows that the tuning command (CMD19)
has failed.
The freeze is then due to the delay block involved in the tuning sequence.
To correct this, clear the delay block register DLYB_CR register after
the tuning commands.

Signed-off-by: Christophe Kerello <[email protected]>
Signed-off-by: Yann Gautier <[email protected]>
Reviewed-by: Linus Walleij <[email protected]>
Fixes: 1103f80 ("mmc: mmci_sdmmc: Add execute tuning with delay block")
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Ulf Hansson <[email protected]>

drivers/mmc/host/mmci_stm32_sdmmc.c

@@ -441,6 +441,8 @@ static int sdmmc_dlyb_phase_tuning(struct mmci_host *host, u32 opcode)
 		return -EINVAL;
 	}
 
+	writel_relaxed(0, dlyb->base + DLYB_CR);
+
 	phase = end_of_len - max_len / 2;
 	sdmmc_dlyb_set_cfgr(dlyb, dlyb->unit, phase, false);