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

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Message-ID: <20250313204439.1582652-1-erick.shepherd@ni.com>
Date: Thu, 13 Mar 2025 15:44:38 -0500
From: Erick Shepherd <erick.shepherd@...com>
To: <adrian.hunter@...el.com>
CC: <brad.mouring@...com>, <erick.shepherd@...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

> sdhci is used by a number of drivers (drivers/mmc/host/sdhci*)
> that typically use the regulator framework to meet voltage
> requirements. So that is not the right place to make changes.

> It would be best to put the affected PCI device IDs into
> sdhci_intel_set_power() as I showed.

I see, that makes sense. The majority of our devices are using either
Apollo Lake or Bay Trail host controllers. Would it be ok to expand
your solution to include both? I tested the following change on a few
of our devices and confirmed the delay is called. If this looks good I
can submit a V2 of this patch.

--- a/drivers/mmc/host/sdhci-pci-core.c
+++ b/drivers/mmc/host/sdhci-pci-core.c
@@ -610,9 +610,12 @@ 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 ||
+		    slot->chip->pdev->device == PCI_DEVICE_ID_INTEL_BYT_SD)
+			usleep_range(15000, 17500);
 		return;
-
+	}
 	/*
 	 * Bus power might not enable after D3 -> D0 transition due to the
 	 * present state not yet having propagated. Retry for up to 2ms.
-- 

Regards,
Erick