From: Raul E Rangel Subject: [PATCH v2 2/3] mmc: sdhci: sdhci-pci-o2micro: Check if controller supports 8-bit width Date: Mon, 17 Jun 2019 14:10:13 -0600 Message-ID: <20190617201014.84503-2-rrangel@chromium.org> References: <20190617201014.84503-1-rrangel@chromium.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190617201014.84503-1-rrangel@chromium.org> Sender: linux-kernel-owner@vger.kernel.org To: linux-mmc@vger.kernel.org Cc: ernest.zhang@bayhubtech.com, djkurtz@chromium.org, Raul E Rangel , linux-kernel@vger.kernel.org, Adrian Hunter , Ulf Hansson List-Id: linux-mmc@vger.kernel.org The O2 controller supports 8-bit EMMC access. JESD84-B51 section A.6.3.a defines the bus testing procedure that `mmc_select_bus_width()` implements. This is used to determine the actual bus width of the eMMC. Signed-off-by: Raul E Rangel --- I tested this on an AMD chromebook. $ cat /sys/kernel/debug/mmc1/ios clock: 200000000 Hz actual clock: 200000000 Hz vdd: 21 (3.3 ~ 3.4 V) bus mode: 2 (push-pull) chip select: 0 (don't care) power mode: 2 (on) bus width: 3 (8 bits) timing spec: 9 (mmc HS200) signal voltage: 1 (1.80 V) driver type: 0 (driver type B) Before this patch only 4 bit was negotiated. drivers/mmc/host/sdhci-pci-o2micro.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/mmc/host/sdhci-pci-o2micro.c b/drivers/mmc/host/sdhci-pci-o2micro.c index dd21315922c87..9dc4548271b4b 100644 --- a/drivers/mmc/host/sdhci-pci-o2micro.c +++ b/drivers/mmc/host/sdhci-pci-o2micro.c @@ -395,11 +395,21 @@ int sdhci_pci_o2_probe_slot(struct sdhci_pci_slot *slot) { struct sdhci_pci_chip *chip; struct sdhci_host *host; - u32 reg; + u32 reg, caps; int ret; chip = slot->chip; host = slot->host; + + caps = sdhci_readl(host, SDHCI_CAPABILITIES); + + /* + * mmc_select_bus_width() will test the bus to determine the actual bus + * width. + */ + if (caps & SDHCI_CAN_DO_8BIT) + host->mmc->caps |= MMC_CAP_8_BIT_DATA; + switch (chip->pdev->device) { case PCI_DEVICE_ID_O2_SDS0: case PCI_DEVICE_ID_O2_SEABIRD0: -- 2.22.0.410.gd8fdbe21b5-goog