linux-kernel - Re: sdhci driver card-detect is broken because gpiolib can't fallback to

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Message-ID: <20180926074756.GD2664@lahna.fi.intel.com>
Date:   Wed, 26 Sep 2018 10:47:56 +0300
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Rajat Jain <rajatja@...gle.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Dmitry Torokhov <dtor@...gle.com>, linux-gpio@...r.kernel.org,
        linux-acpi@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        linux-mmc@...r.kernel.org, Rajat Jain <rajatxjain@...il.com>
Subject: Re: sdhci driver card-detect is broken because gpiolib can't
 fallback to _CRS?

Hi,

On Tue, Sep 25, 2018 at 01:54:57PM -0700, Rajat Jain wrote:
> * Use con_id=NULL if it is dealing with a legacy BIOS (i.e. no _DSD
> properties in the ACPI).
> * Use con_id=<actual string> if it is dealing with a modern BIOS (i.e.
> which provides _DSD for the <string> property)

Or you can use con_id=<actual string> everywhere and supply
acpi_dev_add_driver_gpios() where needed to cover cases where BIOS does
not provide _DSD. See also Documentation/acpi/gpio-properties.txt for
more information.

In case of SDHCI I think the correct way is to stick using _CRS lookup
only because there typically is just one GpioInt() and I have not seen a
single BIOS yet where they implement _DSD for this besides yours. If
there is not way to change the BIOS implementation then I guess we just
need to amend the driver to call acpi_dev_add_driver_gpios().