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 <rran...@chromium.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 | 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
