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

From: Philip Rakity
Date: Tue Oct 23 2012 - 09:22:05 EST



On 23 Oct 2012, at 09:19, Pavan Kunapuli <pkunapuli@xxxxxxxxxx> 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@xxxxxxxxxx>
> ---
> 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;

Some systems exist where vmmc regulator exists and vqmmc regulator does not. The vmmc regular is fixed at 3.3v.
Deferring the probe will cause issues.

> }
> 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;
> }
>
> --
> 1.7.1.1
>
> --
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