[PATCH 3/3] mmc: sdhci-esdhc-imx: prevent stack from using higher speed modes

Stefan Agner
2018-06-28T08:13:31Z

If pinctrl configurations for higher speed modes are missing, the
stack currently uses the no 1.8V quirk. This comes close to what
we need but not exactly: E.g. if a eMMC chip uses 1.8V signaling
(by specifying a 1.8V only vqmmc-supply) while not providing any
100MHz/200MHz pinctrl configurations then the SDHCI_QUIRK2_NO_1_8_V
leads the stack to print signaling voltage switch failed errors
continuously:
mmc1: Switching to 3.3V signalling voltage failed

Presumably because the stack tries to use 3.3V signaling:

# cat /sys/kernel/debug/mmc1/ios
...
timing spec: 8 (mmc DDR52)
signal voltage: 0 (3.30 V)
...

With using SDHCI_QUIRK2_NO_UHS_HS200_HS400 we prevent the stack
from choosing any modes require speeds higher than 52MHz while
still allowing to select modes using 1.8V at lower speeds (e.g.
DDR52):

# cat /sys/kernel/debug/mmc1/ios
...
timing spec: 8 (mmc DDR52)
signal voltage: 1 (1.80 V)
...

Signed-off-by: Stefan Agner <stefan@agner.ch>
---
drivers/mmc/host/sdhci-esdhc-imx.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
index 20a420b765b3..4a1c33018072 100644
--- a/drivers/mmc/host/sdhci-esdhc-imx.c
+++ b/drivers/mmc/host/sdhci-esdhc-imx.c
@@ -1165,10 +1165,10 @@ sdhci_esdhc_imx_probe_dt(struct platform_device *pdev,
* fall back to not supporting uhs by specifying no
* 1.8v quirk
*/
- host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
+ host->quirks2 |= SDHCI_QUIRK2_NO_UHS_HS200_HS400;
}
} else {
- host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
+ host->quirks2 |= SDHCI_QUIRK2_NO_UHS_HS200_HS400;
}

/* call to generic mmc_of_parse to support additional capabilities */
--
2.18.0