On Thu, Jun 20, 2019 at 03:07:21PM +0530, Faiz Abbas wrote:
If UHS speed modes are enabled, a compatible SD card switches down to 1.8V during enumeration. If after this a software reboot/crash takes place and on-chip ROM tries to enumerate the SD card, the difference in IO voltages (host @ 3.3V and card @ 1.8V) may end up damaging the card.
The fix for this is to have support for power cycling the card in hardware (with a PORz/soft-reset line causing a power cycle of the card). Because the beaglebone X15 (rev A,B and C), am57xx-evms and am57xx-idks don't have this capability, disable voltage switching for these boards.
The major effect of this is that the maximum supported speed mode is now high speed(50 MHz) down from SDR104(200 MHz).
Signed-off-by: Faiz Abbas faiz_abbas@ti.com
Applied to u-boot/master, thanks!