linux-kernel - Re: [PATCH V3] mmc: sdhci-msm: Ensure SD card power isn't ON when card removed

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Message-ID: <c7lpaij5f5monr7zfeqitncwnau22iollid2gs7okyorlegtmg@jlq65x7ipp25>
Date: Tue, 1 Jul 2025 13:27:42 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Sarthak Garg <quic_sartgarg@...cinc.com>
Cc: Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>, linux-arm-msm@...r.kernel.org,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        quic_cang@...cinc.com, quic_nguyenb@...cinc.com,
        quic_rampraka@...cinc.com, quic_pragalla@...cinc.com,
        quic_sayalil@...cinc.com, quic_nitirawa@...cinc.com,
        quic_bhaskarv@...cinc.com, kernel@....qualcomm.com
Subject: Re: [PATCH V3] mmc: sdhci-msm: Ensure SD card power isn't ON when
 card removed

On Tue, Jul 01, 2025 at 03:36:59PM +0530, Sarthak Garg wrote:
> Many mobile phones feature multi-card tray designs, where the same
> tray is used for both SD and SIM cards. If the SD card is placed
> at the outermost location in the tray, the SIM card may come in
> contact with SD card power-supply while removing the tray, possibly
> resulting in SIM damage.
> 
> To prevent that, make sure the SD card is really inserted by reading
> the Card Detect pin state. If it's not, turn off the power in
> sdhci_msm_check_power_status() and also set the BUS_FAIL power state
> on the controller as part of pwr_irq handling for BUS_ON request.
> 
> Signed-off-by: Sarthak Garg <quic_sartgarg@...cinc.com>
> Acked-by: Adrian Hunter <adrian.hunter@...el.com>

Should this be handled by the MMC core instead?

> ---
>  Changes from v2:
>  As per Konrad Dybcio's comment :
>  - Updated commit text
>  - Removed READ_ONCE as mmc->ops will be present always
>  - Passed the parameter directly to msm_host_writel
>  As per Adrian Hunter's comment :
>  - Removed get_cd function as not much use now
> 
>  Changes from v1:
>  As per Adrian Hunter's comment :
>  - Removed unrelated changes
>  - Created a separate function get_cd for cleaner code
>  - Used READ_ONCE when getting mmc->ops to handle card removal cases
>  - Reordered if check conditions
> ---
>  drivers/mmc/host/sdhci-msm.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
> index bf91cb96a0ea..f99fb3b096d6 100644
> --- a/drivers/mmc/host/sdhci-msm.c
> +++ b/drivers/mmc/host/sdhci-msm.c
> @@ -1579,6 +1579,7 @@ static void sdhci_msm_check_power_status(struct sdhci_host *host, u32 req_type)
>  {
>  	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>  	struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
> +	struct mmc_host *mmc = host->mmc;
>  	bool done = false;
>  	u32 val = SWITCHABLE_SIGNALING_VOLTAGE;
>  	const struct sdhci_msm_offset *msm_offset =
> @@ -1636,6 +1637,12 @@ static void sdhci_msm_check_power_status(struct sdhci_host *host, u32 req_type)
>  				 "%s: pwr_irq for req: (%d) timed out\n",
>  				 mmc_hostname(host->mmc), req_type);
>  	}
> +
> +	if ((req_type & REQ_BUS_ON) && mmc->card && !mmc->ops->get_cd(mmc)) {
> +		sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
> +		host->pwr = 0;
> +	}
> +
>  	pr_debug("%s: %s: request %d done\n", mmc_hostname(host->mmc),
>  			__func__, req_type);
>  }
> @@ -1694,6 +1701,13 @@ static void sdhci_msm_handle_pwr_irq(struct sdhci_host *host, int irq)
>  		udelay(10);
>  	}
>  
> +	if ((irq_status & CORE_PWRCTL_BUS_ON) && mmc->card &&
> +	    !mmc->ops->get_cd(mmc)) {
> +		msm_host_writel(msm_host, CORE_PWRCTL_BUS_FAIL, host,
> +				msm_offset->core_pwrctl_ctl);
> +		return;
> +	}
> +
>  	/* Handle BUS ON/OFF*/
>  	if (irq_status & CORE_PWRCTL_BUS_ON) {
>  		pwr_state = REQ_BUS_ON;
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry