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Subject[PATCH 3/4] 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 <>
Signed-off-by: Yann Gautier <>
drivers/mmc/host/mmci_stm32_sdmmc.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/mmc/host/mmci_stm32_sdmmc.c b/drivers/mmc/host/mmci_stm32_sdmmc.c
index fdaa11f92fe6..a75d3dd34d18 100644
--- a/drivers/mmc/host/mmci_stm32_sdmmc.c
+++ b/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);

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