[RFC PATCH 2/2] mmc: Allow tuning to be skipped during card init

[Erick Shepherd <erick.shepherd@ni.com>]

Add a new field to the mmc_host struct to track when the card should
skip the initial tuning and use it to conditionally stop tuning in the
mmc_sd_init_uhs_card function. Currently the new field only gets set
when a DDR50 card fails to tune, which indicates the card does not
support tuning.

Signed-off-by: Erick Shepherd <erick.shepherd@ni.com>
---
 drivers/mmc/core/sd.c    | 4 +++-
 include/linux/mmc/host.h | 1 +
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index cc757b850e79..353715fd8f53 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -663,7 +663,8 @@ static int mmc_sd_init_uhs_card(struct mmc_card *card)
 	if (!mmc_host_is_spi(card->host) &&
 		(card->host->ios.timing == MMC_TIMING_UHS_SDR50 ||
 		 card->host->ios.timing == MMC_TIMING_UHS_DDR50 ||
-		 card->host->ios.timing == MMC_TIMING_UHS_SDR104)) {
+		 card->host->ios.timing == MMC_TIMING_UHS_SDR104) &&
+		!card->host->skip_init_tune) {
 		err = mmc_execute_tuning(card);
 
 		/*
@@ -676,6 +677,7 @@ static int mmc_sd_init_uhs_card(struct mmc_card *card)
 		if (err && card->host->ios.timing == MMC_TIMING_UHS_DDR50) {
 			pr_warn("%s: ddr50 tuning failed\n",
 				mmc_hostname(card->host));
+			card->host->skip_init_tune = 1;
 			err = 0;
 		}
 	}
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 68f09a955a90..91c4db6837c9 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -486,6 +486,7 @@ struct mmc_host {
 	unsigned int		use_spi_crc:1;
 	unsigned int		claimed:1;	/* host exclusively claimed */
 	unsigned int		doing_init_tune:1; /* initial tuning in progress */
+	unsigned int		skip_init_tune:1;	/* skip the initial tuning */
 	unsigned int		can_retune:1;	/* re-tuning can be used */
 	unsigned int		doing_retune:1;	/* re-tuning in progress */
 	unsigned int		retune_now:1;	/* do re-tuning at next req */
-- 
2.43.0