linux-kernel - Re: [PATCH 1/3] mmc: sdhci: let GPIO based card detection have higher precedence

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Date:	Fri, 26 Jun 2015 14:09:35 +0300
From:	Adrian Hunter <adrian.hunter@...el.com>
To:	"Ivan T. Ivanov" <ivan.ivanov@...aro.org>
CC:	Ulf Hansson <ulf.hansson@...aro.org>,
	Tim Kryger <tim.kryger@...il.com>,
	Aisheng Dong <b29396@...escale.com>, linux-mmc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 1/3] mmc: sdhci: let GPIO based card detection have higher
 precedence

On 26/06/15 14:00, Ivan T. Ivanov wrote:
> 
> On Fri, 2015-06-26 at 13:19 +0300, Adrian Hunter wrote:
>> On 26/06/15 13:00, Ivan T. Ivanov wrote:
>>> Controller could have BROKEN_CARD_DETECTION quirk set, but drivers
>>> could use GPIO to detect card present state. Let, when defined, GPIO
>>> take precedence, so drivers could properly detect card state and not
>>> use polling.
>>>
>>> Signed-off-by: Ivan T. Ivanov ivanov@...aro.org>
>>> ---
>>>  drivers/mmc/host/sdhci.c | 11 +++++++----
>>>  1 file changed, 7 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>>> index bc14452..8bafb9f 100644
>>> --- a/drivers/mmc/host/sdhci.c
>>> +++ b/drivers/mmc/host/sdhci.c
>>> @@ -1601,15 +1601,18 @@ static int sdhci_do_get_cd(struct sdhci_host *host)
>>>         if (host->flags & SDHCI_DEVICE_DEAD)
>>>                 return 0;
>>>
>>> +       /*
>>> +               * Try slot gpio detect, if defined it take precedence
>>> +               * over build in controller functionality
>>> +               */
>>> +       if (!IS_ERR_VALUE(gpio_cd))
>>> +               return !!gpio_cd;
>>> +
>>
>> You've also put it above the MMC_CAP_NONREMOVABLE check which doesn't seem
>> right.
>>
> 
> Probably, but what are the chances that this is valid GIO for non-removable cards.
> I could rework it if you insist.

It is nicer not to have to think "what are the chances", and nicer that the
logic is strictly correct, so yes please.

> 
> Thank you,
> Ivan
> 
>>>         /* If polling/nonremovable, assume that the card is always present. */
>>>         if ((host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION) ||
>>>                                         (host->mmc->caps & MMC_CAP_NONREMOVABLE))
>>>                 return 1;
>>>
>>> -       /* Try slot gpio detect */
>>> -       if (!IS_ERR_VALUE(gpio_cd))
>>> -               return !!gpio_cd;
>>> -
>>>         /* Host native card detect */
>>>         return !!(sdhci_readl(host, SDHCI_PRESENT_STATE) & SDHCI_CARD_PRESENT);
>>>  }
>>> --
>>> 1.9.1
>>>
>>>
>>>
>>
>>
> 
> 

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