rockchip: set initial signal voltage on power off

target/linux/rockchip/patches-5.19/0107-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 <jonas@kwiboo.se>
+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 <jonas@kwiboo.se>
+---
+ drivers/mmc/core/core.c | 2 ++
+ 1 file changed, 2 insertions(+)
+
+--- a/drivers/mmc/core/core.c
++++ b/drivers/mmc/core/core.c
+@@ -1358,6 +1358,8 @@ 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;
+