On Sun, 17 Feb 2019 at 23:14, Jonas Karlman <jonas@xxxxxxxxx> wrote: > > 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. Is the problem limited to a "warm manual re-boot" or does it exists for an emergency reboot as well!? > > Set initial signal voltage in mmc_power_off() to allow re-boot to function. I think this sounds like a reasonable way forward, to improve the situation. > > 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@xxxxxxxxx> > --- > drivers/mmc/core/core.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c > index 5bd58b95d318..69d7021916ae 100644 > --- a/drivers/mmc/core/core.c > +++ b/drivers/mmc/core/core.c > @@ -1684,6 +1684,14 @@ void mmc_power_off(struct mmc_host *host) > if (host->ios.power_mode == MMC_POWER_OFF) > return; > > + mmc_set_initial_signal_voltage(host); I would rather try to move this below mmc_set_initial_state() a few lines below in mmc_power_off(). To me, it seems safer to do the regular power off thingy first. Additionally, I would drop the added delay below, as there is already a delay after calling mmc_set_initial_state() and I think/hope that should be sufficient. > + > + /* > + * This delay should be sufficient to allow the power supply > + * to reach the minimum voltage. > + */ > + mmc_delay(host->ios.power_delay_ms); > + > mmc_pwrseq_power_off(host); > > host->ios.clock = 0; > -- > 2.17.1 > Kind regards Uffe
