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

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Message-ID: <20250313033552.1505631-1-erick.shepherd@ni.com>
Date: Wed, 12 Mar 2025 22:35:52 -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

> 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

I talked to one of our digital hardware engineers who worked on this
issue. He believes that the issue is likely affecting more than just 
Apollo Lake devices and recommended keeping the delay for all of our
devices. Could something like this work?

--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2176,6 +2176,9 @@ EXPORT_SYMBOL_GPL(sdhci_set_power_noreg);
 void sdhci_set_power(struct sdhci_host *host, unsigned char mode,
 		     unsigned short vdd)
 {
+	if (mode == MMC_POWER_OFF)
+		usleep_range(15000, 17500);
+
 	if (IS_ERR(host->mmc->supply.vmmc))
 		sdhci_set_power_noreg(host, mode, vdd);
 	else
  
Regards,
Erick