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Subject[PATCH v2] mmc: host: sdhci-sprd: Fix the incorrect soft reset operation when runtime resuming
Date
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 do 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 add one condition to validate
the MMC_CAP_AGGRESSIVE_PM to decide if we can do software reset for all or
just reset command and data lines.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
Changes from v1:
- Add a specific reset operation instead of changing the core to avoid
affecting other hardware.
---
drivers/mmc/host/sdhci-sprd.c | 38 +++++++++++++++++++++++++++++++++++++-
1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci-sprd.c b/drivers/mmc/host/sdhci-sprd.c
index 603a5d9..174b566 100644
--- a/drivers/mmc/host/sdhci-sprd.c
+++ b/drivers/mmc/host/sdhci-sprd.c
@@ -373,6 +373,42 @@ 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;
+ ktime_t timeout;
+
+ /*
+ * 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->caps & MMC_CAP_AGGRESSIVE_PM))
+ mask = SDHCI_RESET_CMD | SDHCI_RESET_DATA;
+
+ sdhci_writeb(host, mask, SDHCI_SOFTWARE_RESET);
+
+ /* Wait max 100 ms */
+ timeout = ktime_add_ms(ktime_get(), 100);
+
+ /* hw clears the bit when it's done */
+ while (1) {
+ bool timedout = ktime_after(ktime_get(), timeout);
+
+ if (!(sdhci_readb(host, SDHCI_SOFTWARE_RESET) & mask))
+ break;
+ if (timedout) {
+ pr_err("%s: Reset 0x%x never completed.\n",
+ mmc_hostname(host->mmc), (int)mask);
+ sdhci_dumpregs(host);
+ return;
+ }
+ udelay(10);
+ }
+}
+
static struct sdhci_ops sdhci_sprd_ops = {
.read_l = sdhci_sprd_readl,
.write_l = sdhci_sprd_writel,
@@ -381,7 +417,7 @@ 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
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