[PATCH v1] mmc: sdhci-of-dwcmshc: th1520: Increase tuning loop count to 128

[Maksim Kiselev]

Fix SD card tuning error by increasing tuning loop count
from 40(MAX_TUNING_LOOP) to 128.

For some reason the tuning algorithm requires to move through all the taps
of delay line even if the THRESHOLD_MODE (bit 2 in AT_CTRL_R) is used
instead of the LARGEST_WIN_MODE.

Tested-by: Drew Fustini <drew@xxxxxxxx>
Tested-by: Xi Ruoyao <xry111@xxxxxxxxxxx>
Signed-off-by: Maksim Kiselev <bigunclemax@xxxxxxxxx>
---
Previous discussion was here:
https://lore.kernel.org/lkml/CALHCpMhc1F5Ue7U_gsDXREHUZRVQJNYRCJxYxoNqbN=-39jf7A@xxxxxxxxxxxxxx/

 drivers/mmc/host/sdhci-of-dwcmshc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
index 8d6cfb648096..1001b6ea1a89 100644
--- a/drivers/mmc/host/sdhci-of-dwcmshc.c
+++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
@@ -706,6 +706,7 @@ static int th1520_execute_tuning(struct sdhci_host *host, u32 opcode)
 
 	/* perform tuning */
 	sdhci_start_tuning(host);
+	host->tuning_loop_count = 128;
 	host->tuning_err = __sdhci_execute_tuning(host, opcode);
 	if (host->tuning_err) {
 		/* disable auto-tuning upon tuning error */
-- 
2.40.1