mmc: core: Don't do eMMC HW reset when resuming the eMMC card

In case if a pwrseq-emmc has been bound to the host, a call to
mmc_power_up() triggers an eMMC HW reset via the pwrseq_emmc's
->post_power_on() callback. This isn't really what we want, as
mmc_power_up() is called each time when resuming the card.

As a matter of fact, the current approach may also violate the eMMC spec,
as the involved delays managed in pwrseq_emmc assumes both VCC and VCCQ has
been turned on, which isn't the case for VCCQ, unless the regulator is
always on.

Fix this behaviour by aligning to the same procedure used when the mmc host
implements the ->hw_reset() callback and has the MMC_CAP_HW_RESET flag set.
In this way the eMMC HW reset is issued at card detection scan, to cope
with bogus bootloaders and in the error recovery path via the mmc specific
bus_ops->reset() callback.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>

drivers/mmc/core/core.c

@@ -2597,6 +2597,8 @@ EXPORT_SYMBOL(mmc_set_blockcount);
 
 static void mmc_hw_reset_for_init(struct mmc_host *host)
 {
+	mmc_pwrseq_reset(host);
+
 	if (!(host->caps & MMC_CAP_HW_RESET) || !host->ops->hw_reset)
 		return;
 	host->ops->hw_reset(host);

drivers/mmc/core/mmc.c

@@ -27,6 +27,7 @@
 #include "mmc_ops.h"
 #include "quirks.h"
 #include "sd_ops.h"
+#include "pwrseq.h"
 
 #define DEFAULT_CMD6_TIMEOUT_MS	500
 
@@ -2127,6 +2128,7 @@ static int mmc_reset(struct mmc_host *host)
 	} else {
 		/* Do a brute force power cycle */
 		mmc_power_cycle(host, card->ocr);
+		mmc_pwrseq_reset(host);
 	}
 	return mmc_init_card(host, card->ocr, card);
 }

drivers/mmc/core/pwrseq_emmc.c

@@ -56,7 +56,7 @@ static int mmc_pwrseq_emmc_reset_nb(struct notifier_block *this,
 }
 
 static const struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {
-	.post_power_on = mmc_pwrseq_emmc_reset,
+	.reset = mmc_pwrseq_emmc_reset,
 };
 
 static int mmc_pwrseq_emmc_probe(struct platform_device *pdev)