From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rajat Jain Subject: [PATCH] mmc: sdhci-pci: Try "cd" for card-detect lookup before using NULL Date: Thu, 18 Oct 2018 14:51:01 -0700 Message-ID: <20181018215101.169847-1-rajatja@google.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Adrian Hunter , Ulf Hansson , linux-mmc@vger.kernel.org, Linus Walleij Cc: Rajat Jain , rajatxjain@gmail.com, linux-kernel@vger.kernel.org, Mika Westerberg , Andy Shevchenko , Dmitry Torokhov , linux-gpio@vger.kernel.org, linux-acpi@vger.kernel.org List-Id: linux-acpi@vger.kernel.org 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 "-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 --- 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