linux-kernel - Re: [PATCH] sdhci: Forward EPROBE_DEFER on vmmc and vqmmc regulators

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Date:	Thu, 27 Mar 2014 18:47:54 +0100
From:	Mike Looijmans <mike.looijmans@...ic.nl>
To:	Georgi Djakov <gdjakov@...sol.com>, cjb@...top.org,
	linux-mmc@...r.kernel.org
CC:	linux-kernel@...r.kernel.org, git@...inx.com
Subject: Re: [PATCH] sdhci: Forward EPROBE_DEFER on vmmc and vqmmc regulators

On 26-3-2014 16:09, Georgi Djakov wrote:
> On 03/07/2014 04:18 PM, Mike Looijmans wrote:
>> If vmmc or vqmmc regulators are controlled by an I2C device, the
>> request for the regulator is likely to fail because the I2C bus has
>> not been probed yet. The sdhci then incorrectly assumes that the user
>> never wanted to use a regulator anyway and continues without ever
>> enabling or configuring the required regulator.
>>
>> To solve this, when a required voltage regulator returns
>> EPROBE_DEFER, signalling that the regulator exists but is not
>> available yet, forward this error to the probe method instead
>> of simply assuming that the user never wanted to use a regulator
>> anyway.
>>
>> Tested on a custom board that has an I2C regulator for one of the sdhcis
>> and no regulators at all for the other. This patch enables such a system
>> to work correctly.
>> ---
>>   drivers/mmc/host/sdhci.c |    8 ++++++--
>>   1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index 34aef81..43b90c1 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -2972,6 +2972,8 @@ int sdhci_add_host(struct sdhci_host *host)
>>       host->vqmmc = regulator_get_optional(mmc_dev(mmc), "vqmmc");
>>       if (IS_ERR_OR_NULL(host->vqmmc)) {
>>           if (PTR_ERR(host->vqmmc) < 0) {
>> +            if (PTR_ERR(host->vqmmc) == -EPROBE_DEFER)
>> +                return -EPROBE_DEFER;
>>               pr_info("%s: no vqmmc regulator found\n",
>>                   mmc_hostname(mmc));
>>               host->vqmmc = NULL;
>> @@ -3048,8 +3050,10 @@ int sdhci_add_host(struct sdhci_host *host)
>>       host->vmmc = regulator_get_optional(mmc_dev(mmc), "vmmc");
>>       if (IS_ERR_OR_NULL(host->vmmc)) {
>>           if (PTR_ERR(host->vmmc) < 0) {
>> -            pr_info("%s: no vmmc regulator found\n",
>> -                mmc_hostname(mmc));
>> +            if (PTR_ERR(host->vmmc) == -EPROBE_DEFER)
>> +                return -EPROBE_DEFER;
>> +            pr_info("%s: no vmmc regulator found (%d)\n",
>
> I suggest using %ld here. The rest looks fine to me! Thanks!

Does this mean you're waiting for a patch v2 that I should submit?

>
>> +                mmc_hostname(mmc), PTR_ERR(host->vmmc));
>>               host->vmmc = NULL;
>>           }
>>       }
>>
>
> BR,
> Georgi
>


-- 
Mike Looijmans
--
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