From: Rajat Jain <rajatja@google.com>
To: Adrian Hunter <adrian.hunter@intel.com>,
Ulf Hansson <ulf.hansson@linaro.org>,
linux-mmc@vger.kernel.org,
Linus Walleij <linus.walleij@linaro.org>
Cc: Rajat Jain <rajatja@google.com>,
rajatxjain@gmail.com, linux-kernel@vger.kernel.org,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Dmitry Torokhov <dtor@google.com>,
linux-gpio@vger.kernel.org, linux-acpi@vger.kernel.org
Subject: [PATCH] mmc: sdhci-pci: Try "cd" for card-detect lookup before using NULL
Date: Thu, 18 Oct 2018 14:51:01 -0700 [thread overview]
Message-ID: <20181018215101.169847-1-rajatja@google.com> (raw)
In-Reply-To: <CACRpkdY7eaYk81CU8gmHKfWB82_qNJur=c=7SCRuW+BNeL=Oiw@mail.gmail.com>
Problem:
The card detect IRQ does not work with modern BIOS (that want
to use DSD to provide the card detect GPIO to the driver).
Details:
(Discussion: https://lkml.org/lkml/2018/9/25/1113)
The mmc core provides the mmc_gpiod_request_cd() API to let host drivers
request the gpio descriptor for the "card detect" (or carrier detect?) pin.
This pin is specified in the ACPI for the SDHC device:
* Either as a resource using _CRS. This is a method used by legacy BIOS.
(The driver needs to tell which resource index).
* Or as a named property ("cd-gpio") in DSD (which may internally point
to an entry in _CRS). This way, the driver can lookup using a string.
This is what modern BIOS prefer to use.
This API finally results in a call to the following code:
struct gpio_desc *acpi_find_gpio(..., const char *con_id,...)
{
...
/* Lookup gpio (using "<con_id>-gpio") in the _DSD */
...
if (!acpi_can_fallback_to_crs(adev, con_id))
return ERR_PTR(-ENOENT);
...
/* Falling back to _CRS is allowed, Lookup gpio in the _CRS */
...
}
Note that this means that if the ACPI has _DSD properties, the kernel
will never use _CRS for the lookup (Because acpi_can_fallback_to_crs()
will always be false for any device hat has _DSD entries).
The SDHCI driver is thus currently broken on a modern BIOS (even if
BIOS provides both _CRS and DSD entries, either of which could be used for
a successful lookup). Ironically, none of these will be used for the
lookup currently because:
* Since the con_id is NULL, acpi_find_gpio() does not find a matching
entry in DSDT. (The DSDT entry has the property name = "cd-gpio")
* Because ACPI contains DSDT entries, thus acpi_can_fallback_to_crs()
returns false (because device properties have been populated from
DSD), thus the _CRS is never used for the lookup.
Fix:
Try "cd" for lookup in the _DSD before falling back to using NULL so
as to try looking up in the _CRS.
I've tested this patch successfully with both Legacy BIOS (that
provide only _CRS method) as well as modern BIOS (that provide both
_CRS and DSD). Also the use of "cd" also appears to be farly consistent
across other users of this API (other MMC host controller drivers).
Signed-off-by: Rajat Jain <rajatja@google.com>
---
drivers/mmc/host/sdhci-pci-core.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
index 7bfd366d970d..e53333c695b3 100644
--- a/drivers/mmc/host/sdhci-pci-core.c
+++ b/drivers/mmc/host/sdhci-pci-core.c
@@ -1762,8 +1762,13 @@ static struct sdhci_pci_slot *sdhci_pci_probe_slot(
device_init_wakeup(&pdev->dev, true);
if (slot->cd_idx >= 0) {
- ret = mmc_gpiod_request_cd(host->mmc, NULL, slot->cd_idx,
+ ret = mmc_gpiod_request_cd(host->mmc, "cd", slot->cd_idx,
slot->cd_override_level, 0, NULL);
+ if (ret && ret != -EPROBE_DEFER)
+ ret = mmc_gpiod_request_cd(host->mmc, NULL,
+ slot->cd_idx,
+ slot->cd_override_level,
+ 0, NULL);
if (ret == -EPROBE_DEFER)
goto remove;
--
2.19.1.568.g152ad8e336-goog
next prev parent reply other threads:[~2018-10-18 21:51 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-25 20:54 sdhci driver card-detect is broken because gpiolib can't fallback to _CRS? Rajat Jain
2018-09-26 7:47 ` Mika Westerberg
2018-09-26 8:42 ` Andy Shevchenko
2018-09-26 19:25 ` Rajat Jain
2018-09-27 7:26 ` Andy Shevchenko
2018-09-27 17:56 ` Rajat Jain
2018-09-28 8:42 ` Linus Walleij
2018-09-28 12:34 ` Rajat Jain
2018-09-28 13:13 ` Linus Walleij
2018-10-18 21:51 ` Rajat Jain [this message]
2018-10-19 9:13 ` [PATCH] mmc: sdhci-pci: Try "cd" for card-detect lookup before using NULL Andy Shevchenko
2018-10-22 23:34 ` Rajat Jain
2018-10-24 10:02 ` Andy Shevchenko
2018-10-24 18:03 ` Dmitry Torokhov
2018-10-29 15:23 ` Andy Shevchenko
2018-10-29 17:22 ` Rajat Jain
2018-10-29 17:43 ` Andy Shevchenko
2018-10-29 19:43 ` Rajat Jain
2018-10-29 22:17 ` [PATCH v2] " Rajat Jain
2018-10-30 7:53 ` Adrian Hunter
2018-11-12 11:05 ` Ulf Hansson
2018-11-12 11:25 ` Andy Shevchenko
2018-11-13 1:26 ` Rajat Jain
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