linux-kernel - [PATCH] mmc: sdhci-of-arasan: Ensure CD logic stabilization before power-up

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Message-ID: <20250721095357.3783222-1-sai.krishna.potthuri@amd.com>
Date: Mon, 21 Jul 2025 15:23:57 +0530
From: Sai Krishna Potthuri <sai.krishna.potthuri@....com>
To: Adrian Hunter <adrian.hunter@...el.com>, Michal Simek
	<michal.simek@....com>, Ulf Hansson <ulf.hansson@...aro.org>
CC: <linux-mmc@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <git@....com>, <saikrishna12468@...il.com>,
	Sai Krishna Potthuri <sai.krishna.potthuri@....com>
Subject: [PATCH] mmc: sdhci-of-arasan: Ensure CD logic stabilization before power-up

During SD suspend/resume without a full card rescan (when using
non-removable SD cards for rootfs), the SD card initialization may fail
after resume. This occurs because, after a host controller reset, the
card detect logic may take time to stabilize due to debounce logic.
Without waiting for stabilization, the host may attempt powering up the
card prematurely, leading to command timeouts during resume flow.
Add sdhci_arasan_set_power_and_bus_voltage() to wait for the card detect
stable bit before power up the card. Since the stabilization time
is not fixed, a maximum timeout of one second is used to ensure
sufficient wait time for the card detect signal to stabilize.

Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@....com>
---
 drivers/mmc/host/sdhci-of-arasan.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/sdhci-of-arasan.c b/drivers/mmc/host/sdhci-of-arasan.c
index 42878474e56e..3ce55009ba4a 100644
--- a/drivers/mmc/host/sdhci-of-arasan.c
+++ b/drivers/mmc/host/sdhci-of-arasan.c
@@ -99,6 +99,9 @@
 #define HIWORD_UPDATE(val, mask, shift) \
 		((val) << (shift) | (mask) << ((shift) + 16))
 
+#define CD_STABLE_TIMEOUT_US		1000000
+#define CD_STABLE_MAX_SLEEP_US		10
+
 /**
  * struct sdhci_arasan_soc_ctl_field - Field used in sdhci_arasan_soc_ctl_map
  *
@@ -514,6 +517,23 @@ static int sdhci_arasan_voltage_switch(struct mmc_host *mmc,
 	return -EINVAL;
 }
 
+static void sdhci_arasan_set_power_and_bus_voltage(struct sdhci_host *host, unsigned char mode,
+						   unsigned short vdd)
+{
+	u32 reg;
+
+	/*
+	 * Ensure that the card detect logic has stabilized before powering up, this is
+	 * necessary after a host controller reset.
+	 */
+	if (mode == MMC_POWER_UP) {
+		readl_poll_timeout(host->ioaddr + SDHCI_PRESENT_STATE, reg, reg & SDHCI_CD_STABLE,
+				   CD_STABLE_MAX_SLEEP_US, CD_STABLE_TIMEOUT_US);
+	}
+
+	sdhci_set_power_and_bus_voltage(host, mode, vdd);
+}
+
 static const struct sdhci_ops sdhci_arasan_ops = {
 	.set_clock = sdhci_arasan_set_clock,
 	.get_max_clock = sdhci_pltfm_clk_get_max_clock,
@@ -521,7 +541,7 @@ static const struct sdhci_ops sdhci_arasan_ops = {
 	.set_bus_width = sdhci_set_bus_width,
 	.reset = sdhci_arasan_reset,
 	.set_uhs_signaling = sdhci_set_uhs_signaling,
-	.set_power = sdhci_set_power_and_bus_voltage,
+	.set_power = sdhci_arasan_set_power_and_bus_voltage,
 	.hw_reset = sdhci_arasan_hw_reset,
 };
 
@@ -570,7 +590,7 @@ static const struct sdhci_ops sdhci_arasan_cqe_ops = {
 	.set_bus_width = sdhci_set_bus_width,
 	.reset = sdhci_arasan_reset,
 	.set_uhs_signaling = sdhci_set_uhs_signaling,
-	.set_power = sdhci_set_power_and_bus_voltage,
+	.set_power = sdhci_arasan_set_power_and_bus_voltage,
 	.irq = sdhci_arasan_cqhci_irq,
 };
 
-- 
2.25.1