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

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Message-ID: <a7d1bf5d-6101-4282-92a8-11f9f3569d8b@intel.com>
Date: Wed, 12 Mar 2025 14:44:04 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: Erick Shepherd <erick.shepherd@...com>
CC: <brad.mouring@...com>, <gratian.crisan@...rson.com>,
	<kyle.roeschley@...com>, <linux-kernel@...r.kernel.org>,
	<linux-mmc@...r.kernel.org>, <ulf.hansson@...aro.org>
Subject: Re: [PATCH] mmc: core: Wait for Vdd to settle on card power off

On 7/03/25 23:16, Erick Shepherd wrote:
>> It probably should be dealt with in the ->set_power() callback.
>> Is it one of the PCI devices in sdhci-pci-core.c?
> 
> Sure, I can move the delay to sdhci_set_power(). It looks like that
> gets called right before the if-statement in the change I proposed
> so the behavior should be the same, unless host->ops->set_power is set.
> 
> I believe we saw this failure on devices using the Intel Atom E3930
> and E3940, which are Apollo Lake. It looks like there is an entry in
> sdhci-pci-core.c. Does that change what we should do?

What about something like this?

diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
index 1f0bd723f011..0789df732e93 100644
--- a/drivers/mmc/host/sdhci-pci-core.c
+++ b/drivers/mmc/host/sdhci-pci-core.c
@@ -610,8 +610,11 @@ static void sdhci_intel_set_power(struct sdhci_host *host, unsigned char mode,
 
 	sdhci_set_power(host, mode, vdd);
 
-	if (mode == MMC_POWER_OFF)
+	if (mode == MMC_POWER_OFF) {
+		if (slot->chip->pdev->device == PCI_DEVICE_ID_INTEL_APL_SD)
+			usleep_range(15000, 17500);
 		return;
+	}
 
 	/*
 	 * Bus power might not enable after D3 -> D0 transition due to the