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authorRajat Jain <rajatja@google.com>2018-10-29 15:17:01 -0700
committerUlf Hansson <ulf.hansson@linaro.org>2018-11-19 12:01:18 +0100
commitcdcefe6bd9df754f528ffc339d3cc143cea4ddf6 (patch)
treecec9cbae6b6b1cd083560b0b2b8f2dd61a381de5 /drivers/mmc
parentccda4af0f4b92f7b4c308d3acc262f4a7e3affad (diff)
mmc: sdhci-pci: Try "cd" for card-detect lookup before using NULL
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: The mmc core provides the mmc_gpiod_request_cd() API to let host drivers request the gpio descriptor for the "card 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-gpios"/"cd-gpio") in _DSD (which internally points 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 (for index based lookup) and _DSD entries (for string based 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-gpios") * 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" appears to be fairly consistent across other users of this API (other MMC host controller drivers). Link: https://lkml.org/lkml/2018/9/25/1113 Signed-off-by: Rajat Jain <rajatja@google.com> Acked-by: Adrian Hunter <adrian.hunter@intel.com> Fixes: f10e4bf6632b ("gpio: acpi: Even more tighten up ACPI GPIO lookups") Cc: stable@vger.kernel.org Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Diffstat (limited to 'drivers/mmc')
-rw-r--r--drivers/mmc/host/sdhci-pci-core.c7
1 files changed, 6 insertions, 1 deletions
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;