Re: [PATCH 2/2] mmc: sdhci: Defer probe if regulator_get fails

From: Lucas Stach <dev@lynxeye.de>
To: Pavan Kunapuli <pkunapuli@nvidia.com>
Cc: linux@arm.linux.org.uk, swarren@wwwdotorg.org,
	linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-tegra@vger.kernel.org, cjb@laptop.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 2/2] mmc: sdhci: Defer probe if regulator_get fails
Date: Tue, 23 Oct 2012 09:57:27 +0200	[thread overview]
Message-ID: <1350979047.20572.6.camel@tellur> (raw)
In-Reply-To: <1350976740-19284-3-git-send-email-pkunapuli@nvidia.com>

Am Dienstag, den 23.10.2012, 12:49 +0530 schrieb Pavan Kunapuli:
> vmmc and vqmmc regulators control the voltage to
> the host and device. Defer the probe if either of
> them is not registered.
> 
Does this work with boards where we don't have any MMC supplies? Or are
we just deferring the probe indefinitely there?

For boards that power MMC unconditionally, are we supposed to add dummy
regulators to make them work with this patchset?

> Signed-off-by: Pavan Kunapuli <pkunapuli@nvidia.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;
>  }
>  