[PATCH v3 2/2] mmc: litex_mmc: Set mandatory idle clocks before CMD0

Inochi Amaoto
2026-04-26T11:20:27Z

The litex_mmc driver assumes the card is already probed in the BIOS
and skip the phy initialization. This will cause the command fail
like the following when the old card is unplugged and then insert
a new card:

[ 62.923593] litex-mmc f0004000.mmc: Command (cmd 8) error, status -110
[ 62.949717] litex-mmc f0004000.mmc: Command (cmd 55) error, status -110
[ 62.976606] litex-mmc f0004000.mmc: Command (cmd 55) error, status -110
[ 63.002516] litex-mmc f0004000.mmc: Command (cmd 55) error, status -110
[ 63.028442] litex-mmc f0004000.mmc: Command (cmd 55) error, status -110

Add required clock settings and initialization for the CMD 0, so it can
probe the new card.

Fixes: 92e099104729 ("mmc: Add driver for LiteX's LiteSDCard interface")
Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
---
drivers/mmc/host/litex_mmc.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/drivers/mmc/host/litex_mmc.c b/drivers/mmc/host/litex_mmc.c
index a8d9c0ece16a..c984398d0803 100644
--- a/drivers/mmc/host/litex_mmc.c
+++ b/drivers/mmc/host/litex_mmc.c
@@ -68,6 +68,9 @@
#define SD_SLEEP_US 5
#define SD_TIMEOUT_US 20000

+#define SD_INIT_DELAY_US 1000
+#define SD_INIT_CLK_HZ 400000
+
#define SDIRQ_CARD_DETECT 1
#define SDIRQ_SD_TO_MEM_DONE 2
#define SDIRQ_MEM_TO_SD_DONE 4
@@ -142,6 +145,12 @@ static int litex_mmc_send_cmd(struct litex_mmc_host *host,
int ret;
u8 evt;

+ if (cmd == MMC_GO_IDLE_STATE) {
+ litex_mmc_setclk(host, SD_INIT_CLK_HZ);
+ litex_write8(host->sdphy + LITEX_PHY_INITIALIZE, 1);
+ fsleep(SD_INIT_DELAY_US);
+ }
+
litex_write32(host->sdcore + LITEX_CORE_CMDARG, arg);
litex_write32(host->sdcore + LITEX_CORE_CMDCMD,
cmd << 8 | transfer << 5 | response_len);
--
2.54.0