src/patches/linux/aarch64/0005-mmc-core-set-initial-signal-voltage-on-power-off.patch

   1 From dfacc132a5be8eb643495f8ca693fd59368cc262 Mon Sep 17 00:00:00 2001
   2 From: Jonas Karlman <jonas@kwiboo.se>
   3 Date: Sun, 17 Feb 2019 22:14:38 +0000
   4 Subject: [PATCH 5/8] mmc: core: set initial signal voltage on power off
   5
   6 Some boards have SD card connectors where the power rail cannot be switched
   7 off by the driver. If the card has not been power cycled, it may still be
   8 using 1.8V signaling after a warm re-boot. Bootroms expecting 3.3V signaling
   9 will fail to boot from a UHS card that continue to use 1.8V signaling.
  10
  11 Set initial signal voltage in mmc_power_off() to allow re-boot to function.
  12
  13 This fixes re-boot with UHS cards on Asus Tinker Board (Rockchip RK3288),
  14 same issue have been seen on some Rockchip RK3399 boards.
  15
  16 I am sending this as a RFC because I have no insights into SD/MMC subsystem,
  17 this change fix a re-boot issue on my boards and does not break emmc/sdio.
  18 Is this an acceptable workaround? Any advice is appreciated.
  19
  20 Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
  21 ---
  22  drivers/mmc/core/core.c | 8 ++++++++
  23  1 file changed, 8 insertions(+)
  24
  25 diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
  26 index 3d3e0ca52614..33cb13b7bf88 100644
  27 --- a/drivers/mmc/core/core.c
  28 +++ b/drivers/mmc/core/core.c
  29 @@ -1363,6 +1363,14 @@ void mmc_power_off(struct mmc_host *host)
  30         if (host->ios.power_mode == MMC_POWER_OFF)
  31                 return;
  32
  33 +       mmc_set_initial_signal_voltage(host);
  34 +
  35 +       /*
  36 +        * This delay should be sufficient to allow the power supply
  37 +        * to reach the minimum voltage.
  38 +        */
  39 +       mmc_delay(host->ios.power_delay_ms);
  40 +
  41         mmc_pwrseq_power_off(host);
  42
  43         host->ios.clock = 0;
  44 --
  45 2.34.1
  46