linux-kernel - [PATCH] mmc: core: Wait for Vdd to settle on card power off

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Message-ID: <20250211214611.469260-1-erick.shepherd@ni.com>
Date: Tue, 11 Feb 2025 15:46:11 -0600
From: Erick Shepherd <erick.shepherd@...com>
To: <linux-kernel@...r.kernel.org>
CC: <linux-mmc@...r.kernel.org>, <ulf.hansson@...aro.org>,
        <adrian.hunter@...el.com>, <gratian.crisan@...rson.com>,
        Erick Shepherd
	<erick.shepherd@...com>,
        Kyle Roeschley <kyle.roeschley@...com>,
        Brad Mouring
	<brad.mouring@...com>
Subject: [PATCH] mmc: core: Wait for Vdd to settle on card power off

The SD spec version 6.0 section 6.4.1.5 requires that Vdd must be
lowered to less than 0.5V for a minimum of 1 ms when powering off a
card. Increase our wait to 15 ms so that voltage has time to drain down
to 0.5V.

Signed-off-by: Kyle Roeschley <kyle.roeschley@...com>
Signed-off-by: Brad Mouring <brad.mouring@...com>
Signed-off-by: Erick Shepherd <erick.shepherd@...com>
---
 drivers/mmc/host/sdhci.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index f4a7733a8ad2..b15a1f107549 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2415,6 +2415,9 @@ void sdhci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 	else
 		sdhci_set_power(host, ios->power_mode, ios->vdd);
 
+	if (ios->power_mode == MMC_POWER_OFF)
+		mdelay(15);
+
 	if (host->ops->platform_send_init_74_clocks)
 		host->ops->platform_send_init_74_clocks(host, ios->power_mode);
 
-- 
2.43.0