linux-kernel - [PATCH 2/3] mmc: sdhci: sdhci-pci-o2micro: Check if controller supports 8-bit width

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Message-Id: <20190610185354.35310-2-rrangel@chromium.org>
Date:   Mon, 10 Jun 2019 12:53:52 -0600
From:   Raul E Rangel <rrangel@...omium.org>
To:     linux-mmc@...r.kernel.org
Cc:     ernest.zhang@...hubtech.com, djkurtz@...omium.org,
        Raul E Rangel <rrangel@...omium.org>,
        linux-kernel@...r.kernel.org,
        Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>
Subject: [PATCH 2/3] mmc: sdhci: sdhci-pci-o2micro: Check if controller supports 8-bit width

The O2 controller supports 8-bit EMMC access. mmc_select_bus_width()
will be used to determine if the MMC supports 8-bit or 4-bit access.

Signed-off-by: Raul E Rangel <rrangel@...omium.org>
---
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 | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci-pci-o2micro.c b/drivers/mmc/host/sdhci-pci-o2micro.c
index dd21315922c87..07bb91cbdf1f8 100644
--- a/drivers/mmc/host/sdhci-pci-o2micro.c
+++ b/drivers/mmc/host/sdhci-pci-o2micro.c
@@ -395,11 +395,16 @@ 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);
+	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.rc2.383.gf4fbbf30c2-goog