linux-kernel - Re: [PATCH v2] mmc: host: Wait for Vdd to settle on card power off

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Message-ID: <5081fa69-32cb-4fd4-bad5-5f33032efc39@intel.com>
Date: Thu, 20 Mar 2025 09:25:49 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: Erick Shepherd <erick.shepherd@...com>, <linux-mmc@...r.kernel.org>
CC: <ulf.hansson@...aro.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] mmc: host: Wait for Vdd to settle on card power off

On 14/03/25 21:50, Erick Shepherd wrote:
> 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 wait to 15 ms so that voltage has time to drain down
> to 0.5V and cards can power off correctly. Issues with voltage drain
> time were only observed on Apollo Lake and Bay Trail host controllers
> so this fix is limited to those devices.
> 
> Signed-off-by: Erick Shepherd <erick.shepherd@...com>

Can we leave a blank line after the block.  It was that way before.

With that, you can add:

Acked-by: Adrian Hunter <adrian.hunter@...el.com>

> ---
>  drivers/mmc/host/sdhci-pci-core.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
> index 1f0bd723f011..b1f7c11ea61e 100644
> --- 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;
> -
> +	}

Blank line here

>  	/*
>  	 * Bus power might not enable after D3 -> D0 transition due to the
>  	 * present state not yet having propagated. Retry for up to 2ms.