diff --git a/target/linux/rockchip/patches-5.4/108-rfc-mmc-core-set-initial-signal-voltage-on-power-off.patch b/target/linux/rockchip/patches-5.4/108-rfc-mmc-core-set-initial-signal-voltage-on-power-off.patch new file mode 100644 index 00000000000000..6597ee4776bf54 --- /dev/null +++ b/target/linux/rockchip/patches-5.4/108-rfc-mmc-core-set-initial-signal-voltage-on-power-off.patch @@ -0,0 +1,35 @@ +From 0d329112c709d6cfedf0fffb19f0cc6b19043f6b Mon Sep 17 00:00:00 2001 +From: Jonas Karlman +Date: Wed, 20 Feb 2019 07:38:34 +0000 +Subject: [PATCH] mmc: core: set initial signal voltage on power off + +Some boards have SD card connectors where the power rail cannot be switched +off by the driver. If the card has not been power cycled, it may still be +using 1.8V signaling after a warm re-boot. Bootroms expecting 3.3V signaling +will fail to boot from a UHS card that continue to use 1.8V signaling. + +Set initial signal voltage in mmc_power_off() to allow re-boot to function. + +This fixes re-boot with UHS cards on Asus Tinker Board (Rockchip RK3288), +same issue have been seen on some Rockchip RK3399 boards. + +I am sending this as a RFC because I have no insights into SD/MMC subsystem, +this change fix a re-boot issue on my boards and does not break emmc/sdio. +Is this an acceptable workaround? Any advice is appreciated. + +Signed-off-by: Jonas Karlman +--- + drivers/mmc/core/core.c | 2 ++ + 1 file changed, 2 insertions(+) + +--- a/drivers/mmc/core/core.c ++++ b/drivers/mmc/core/core.c +@@ -1368,6 +1368,8 @@ void mmc_power_off(struct mmc_host *host + + mmc_pwrseq_power_off(host); + ++ mmc_set_initial_signal_voltage(host); ++ + host->ios.clock = 0; + host->ios.vdd = 0; +