linux-kernel - [PATCH v4] mmc: host: sdhci-sprd: Fix the incorrect soft reset operation when runtime resuming

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Date:   Wed, 17 Jul 2019 10:28:52 +0800
From:   Baolin Wang <baolin.wang@...aro.org>
To:     adrian.hunter@...el.com, ulf.hansson@...aro.org,
        zhang.lyra@...il.com, orsonzhai@...il.com
Cc:     baolin.wang@...aro.org, vincent.guittot@...aro.org,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v4] mmc: host: sdhci-sprd: Fix the incorrect soft reset operation when runtime resuming

In sdhci_runtime_resume_host() function, we will always do software reset
for all, which will cause Spreadtrum host controller work abnormally after
resuming.

Thus for Spreadtrum platform that will not power down the SD/eMMC card during
runtime suspend, we should not do software reset for all. To fix this
issue, adding a specific reset operation that adds one condition to validate
the power mode to decide if we can do software reset for all or just reset
command and data lines.

Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
---
Changess from v3:
 - Use ios.power_mode to validate if the card is power down or not.

Changes from v2:
 - Simplify the sdhci_sprd_reset() by issuing sdhci_reset().

Changes from v1:
 - Add a specific reset operation instead of changing the core to avoid
 affecting other hardware.
---
 drivers/mmc/host/sdhci-sprd.c |   19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci-sprd.c b/drivers/mmc/host/sdhci-sprd.c
index 603a5d9..94f9726 100644
--- a/drivers/mmc/host/sdhci-sprd.c
+++ b/drivers/mmc/host/sdhci-sprd.c
@@ -373,6 +373,23 @@ static unsigned int sdhci_sprd_get_max_timeout_count(struct sdhci_host *host)
 	return 1 << 31;
 }
 
+static void sdhci_sprd_reset(struct sdhci_host *host, u8 mask)
+{
+	struct mmc_host *mmc = host->mmc;
+
+	/*
+	 * When try to reset controller after runtime suspend, we should not
+	 * reset for all if the SD/eMMC card is not power down, just reset
+	 * command and data lines instead. Otherwise will meet some strange
+	 * behaviors for Spreadtrum host controller.
+	 */
+	if (host->runtime_suspended && (mask & SDHCI_RESET_ALL) &&
+	    mmc->ios.power_mode == MMC_POWER_ON)
+		mask = SDHCI_RESET_CMD | SDHCI_RESET_DATA;
+
+	sdhci_reset(host, mask);
+}
+
 static struct sdhci_ops sdhci_sprd_ops = {
 	.read_l = sdhci_sprd_readl,
 	.write_l = sdhci_sprd_writel,
@@ -381,7 +398,7 @@ static unsigned int sdhci_sprd_get_max_timeout_count(struct sdhci_host *host)
 	.get_max_clock = sdhci_sprd_get_max_clock,
 	.get_min_clock = sdhci_sprd_get_min_clock,
 	.set_bus_width = sdhci_set_bus_width,
-	.reset = sdhci_reset,
+	.reset = sdhci_sprd_reset,
 	.set_uhs_signaling = sdhci_sprd_set_uhs_signaling,
 	.hw_reset = sdhci_sprd_hw_reset,
 	.get_max_timeout_count = sdhci_sprd_get_max_timeout_count,
-- 
1.7.9.5