linux-kernel - [PATCH] mmc: sdhci-esdhc-imx: wait for data transfer completion before reset

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Message-Id: <20251203095850.4019706-1-ziniu.wang_1@nxp.com>
Date: Wed,  3 Dec 2025 17:58:50 +0800
From: ziniu.wang_1@....com
To: adrian.hunter@...el.com,
	haibo.chen@....com,
	ulf.hansson@...aro.org
Cc: shawnguo@...nel.org,
	s.hauer@...gutronix.de,
	kernel@...gutronix.de,
	festevam@...il.com,
	linux-mmc@...r.kernel.org,
	s32@....com,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] mmc: sdhci-esdhc-imx: wait for data transfer completion before reset

From: Luke Wang <ziniu.wang_1@....com>

On IMX7ULP platforms, certain SD cards (e.g. Kingston Canvas Go! Plus)
cause system hangs and reboots during manual tuning. These cards exhibit
large gaps (~16us) between tuning command response and data transmission.
When CRC errors occur during tuning, the code assumes data errors even
tuning data hasn't been fully received and then reset host data circuit.

Per IMX7ULP reference manual, reset operations (RESET_DATA/ALL) need to
make sure no active data transfers. Previously, resetting while data was
in-flight caused unknown behavior. This patch adds polling for data
transfer completion before executing resets.

Signed-off-by: Luke Wang <ziniu.wang_1@....com>
---
 drivers/mmc/host/sdhci-esdhc-imx.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
index a7a5df673b0f..affde1936510 100644
--- a/drivers/mmc/host/sdhci-esdhc-imx.c
+++ b/drivers/mmc/host/sdhci-esdhc-imx.c
@@ -1453,6 +1453,21 @@ static void esdhc_set_uhs_signaling(struct sdhci_host *host, unsigned timing)
 
 static void esdhc_reset(struct sdhci_host *host, u8 mask)
 {
+	u32 present_state;
+	int ret;
+
+	/*
+	 * For data or full reset, ensure any active data transfer completes
+	 * before resetting to avoid system hang.
+	 */
+	if (mask & (SDHCI_RESET_DATA | SDHCI_RESET_ALL)) {
+		ret = readl_poll_timeout_atomic(host->ioaddr + ESDHC_PRSSTAT, present_state,
+						!(present_state & SDHCI_DATA_INHIBIT), 2, 100000);
+		if (ret == -ETIMEDOUT)
+			dev_warn(mmc_dev(host->mmc),
+				 "timeout waiting for data transfer completion\n");
+	}
+
 	sdhci_and_cqhci_reset(host, mask);
 
 	sdhci_writel(host, host->ier, SDHCI_INT_ENABLE);
-- 
2.34.1