[PATCH 8/9] mmc: core: Allow CMD13 polling when switch to HS400 mode

[Ulf Hansson <ulf.hansson@linaro.org>]

In cases when the mmc host doesn't support HW busy detection, polling for
busy by using CMD13 is beneficial. The reasons have already been explained
in earlier change logs.

Moreover, when polling with CMD13 during bus timing changes, we should
retry instead of fail when we get CRC errors.

Switching from HS200 to HS400 and reverse includes several steps, where
each step changes the bus speed timing. Let's improve the behaviour during
these sequences, by allowing CMD13 polling for each of the step. Let's also
make sure the CMD13 polling becomes retried, while receiving a CRC error.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
 drivers/mmc/core/mmc.c | 87 +++++++++++++++-----------------------------------
 1 file changed, 26 insertions(+), 61 deletions(-)

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 0b26383..24b9e72 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1094,8 +1094,7 @@ static int mmc_select_hs_ddr(struct mmc_card *card)
 static int mmc_select_hs400(struct mmc_card *card)
 {
 	struct mmc_host *host = card->host;
-	unsigned int max_dtr;
-	int err = 0;
+	int err;
 	u8 val;
 
 	/*
@@ -1105,34 +1104,26 @@ static int mmc_select_hs400(struct mmc_card *card)
 	      host->ios.bus_width == MMC_BUS_WIDTH_8))
 		return 0;
 
-	/* Switch card to HS mode */
-	val = EXT_CSD_TIMING_HS;
-	err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
-			   EXT_CSD_HS_TIMING, val,
-			   card->ext_csd.generic_cmd6_time, 0,
-			   true, false, true);
+	/*
+	 * Switch card to HS mode.
+	 * First reduce to the HS frequency as CMD13 are sent to poll for busy
+	 * and/or to validate the switch status.
+	 */
+	mmc_set_clock(host, card->ext_csd.hs_max_dtr);
+	err = mmc_select_hs(card);
 	if (err) {
 		pr_err("%s: switch to high-speed from hs200 failed, err:%d\n",
 			mmc_hostname(host), err);
 		return err;
 	}
 
-	/* Set host controller to HS timing */
-	mmc_set_timing(card->host, MMC_TIMING_MMC_HS);
-
-	/* Reduce frequency to HS frequency */
-	max_dtr = card->ext_csd.hs_max_dtr;
-	mmc_set_clock(host, max_dtr);
-
-	err = mmc_switch_status(card);
-	if (err)
-		goto out_err;
-
-	/* Switch card to DDR */
-	err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
-			 EXT_CSD_BUS_WIDTH,
-			 EXT_CSD_DDR_BUS_WIDTH_8,
-			 card->ext_csd.generic_cmd6_time);
+	/* Switch card to HS DDR */
+	err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+			   EXT_CSD_BUS_WIDTH,
+			   EXT_CSD_DDR_BUS_WIDTH_8,
+			   card->ext_csd.generic_cmd6_time,
+			   MMC_TIMING_MMC_DDR52,
+			   true, true, true);
 	if (err) {
 		pr_err("%s: switch to bus width for hs400 failed, err:%d\n",
 			mmc_hostname(host), err);
@@ -1144,28 +1135,17 @@ static int mmc_select_hs400(struct mmc_card *card)
 	      card->drive_strength << EXT_CSD_DRV_STR_SHIFT;
 	err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
 			   EXT_CSD_HS_TIMING, val,
-			   card->ext_csd.generic_cmd6_time, 0,
-			   true, false, true);
+			   card->ext_csd.generic_cmd6_time,
+			   MMC_TIMING_MMC_HS400,
+			   true, true, true);
 	if (err) {
 		pr_err("%s: switch to hs400 failed, err:%d\n",
 			 mmc_hostname(host), err);
 		return err;
 	}
 
-	/* Set host controller to HS400 timing and frequency */
-	mmc_set_timing(host, MMC_TIMING_MMC_HS400);
 	mmc_set_bus_speed(card);
-
-	err = mmc_switch_status(card);
-	if (err)
-		goto out_err;
-
 	return 0;
-
-out_err:
-	pr_err("%s: %s failed, error %d\n", mmc_hostname(card->host),
-	       __func__, err);
-	return err;
 }
 
 int mmc_hs200_to_hs400(struct mmc_card *card)
@@ -1187,27 +1167,17 @@ int mmc_hs400_to_hs200(struct mmc_card *card)
 	/* Switch HS400 to HS DDR */
 	val = EXT_CSD_TIMING_HS;
 	err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_HS_TIMING,
-			   val, card->ext_csd.generic_cmd6_time, 0,
-			   true, false, true);
-	if (err)
-		goto out_err;
-
-	mmc_set_timing(host, MMC_TIMING_MMC_DDR52);
-
-	err = mmc_switch_status(card);
+			   val, card->ext_csd.generic_cmd6_time,
+			   MMC_TIMING_MMC_DDR52,
+			   true, true, true);
 	if (err)
 		goto out_err;
 
 	/* Switch HS DDR to HS */
 	err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_BUS_WIDTH,
 			   EXT_CSD_BUS_WIDTH_8, card->ext_csd.generic_cmd6_time,
-			   0, true, false, true);
-	if (err)
-		goto out_err;
-
-	mmc_set_timing(host, MMC_TIMING_MMC_HS);
-
-	err = mmc_switch_status(card);
+			   MMC_TIMING_MMC_HS,
+			   true, true, true);
 	if (err)
 		goto out_err;
 
@@ -1215,14 +1185,9 @@ int mmc_hs400_to_hs200(struct mmc_card *card)
 	val = EXT_CSD_TIMING_HS200 |
 	      card->drive_strength << EXT_CSD_DRV_STR_SHIFT;
 	err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_HS_TIMING,
-			   val, card->ext_csd.generic_cmd6_time, 0,
-			   true, false, true);
-	if (err)
-		goto out_err;
-
-	mmc_set_timing(host, MMC_TIMING_MMC_HS200);
-
-	err = mmc_switch_status(card);
+			   val, card->ext_csd.generic_cmd6_time,
+			   MMC_TIMING_MMC_HS200,
+			   true, true, true);
 	if (err)
 		goto out_err;
 
-- 
1.9.1