linux-kernel - Re: [PATCH 2/2] mmc: sdhci: Defer probe if regulator

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Date:	Tue, 23 Oct 2012 19:10:49 +0900
From:	Jaehoon Chung <jh80.chung@...sung.com>
To:	Pavan Kunapuli <pkunapuli@...dia.com>
Cc:	swarren@...dotorg.org, linux@....linux.org.uk, cjb@...top.org,
	linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org
Subject: Re: [PATCH 2/2] mmc: sdhci: Defer probe if regulator_get fails

I didn't understand why defer the probe?
I think that some board can't control vqmmc or vmmc.

Best Regards,
Jaehoon Chung
On 10/23/2012 04:18 PM, Pavan Kunapuli wrote:
> vmmc and vqmmc regulators control the voltage to
> the host and device. Defer the probe if either of
> them is not registered.
> 
> Signed-off-by: Pavan Kunapuli <pkunapuli@...dia.com>
> ---
>  drivers/mmc/host/sdhci.c |   25 ++++++++++++++++++++++---
>  1 files changed, 22 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 7922adb..925c403 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -2844,11 +2844,17 @@ int sdhci_add_host(struct sdhci_host *host)
>  	    !(host->mmc->caps & MMC_CAP_NONREMOVABLE))
>  		mmc->caps |= MMC_CAP_NEEDS_POLL;
>  
> -	/* If vqmmc regulator and no 1.8V signalling, then there's no UHS */
> +	/*
> +	 * If vqmmc regulator and no 1.8V signalling, then there's no UHS.
> +	 * vqmmc regulator should be present. If it's not present,
> +	 * assume the regulator driver registration is not yet done and
> +	 * defer the probe.
> +	 */
>  	host->vqmmc = regulator_get(mmc_dev(mmc), "vqmmc");
>  	if (IS_ERR(host->vqmmc)) {
> -		pr_info("%s: no vqmmc regulator found\n", mmc_hostname(mmc));
> +		pr_err("%s: no vqmmc regulator found\n", mmc_hostname(mmc));
>  		host->vqmmc = NULL;
> +		return -EPROBE_DEFER;
>  	}
>  	else if (regulator_is_supported_voltage(host->vqmmc, 1800000, 1800000))
>  		regulator_enable(host->vqmmc);
> @@ -2903,10 +2909,17 @@ int sdhci_add_host(struct sdhci_host *host)
>  
>  	ocr_avail = 0;
>  
> +	/*
> +	 * vmmc regulator should be present. If it's not present,
> +	 * assume the regulator driver registration is not yet done
> +	 * and defer the probe.
> +	 */
>  	host->vmmc = regulator_get(mmc_dev(mmc), "vmmc");
>  	if (IS_ERR(host->vmmc)) {
> -		pr_info("%s: no vmmc regulator found\n", mmc_hostname(mmc));
> +		pr_err("%s: no vmmc regulator found\n", mmc_hostname(mmc));
>  		host->vmmc = NULL;
> +		ret = -EPROBE_DEFER;
> +		goto vmmc_err;
>  	} else
>  		regulator_enable(host->vmmc);
>  
> @@ -3121,7 +3134,13 @@ reset:
>  untasklet:
>  	tasklet_kill(&host->card_tasklet);
>  	tasklet_kill(&host->finish_tasklet);
> +vmmc_err:
> +	if (host->vqmmc) {
> +		if (regulator_is_enabled(host->vqmmc))
> +			regulator_disable(host->vqmmc);
>  
> +		regulator_put(host->vqmmc);
> +	}
>  	return ret;
>  }
>  
> 

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