On Thu, Jan 03, 2019 at 09:19:24PM +0100, Marek Vasut wrote:
The mmc_select_mode_and_width() function can be called while the card is in HS200/HS400 mode and can be used to downgrade the card to lower mode, e.g. HS. This is used for example by mmc_boot_part_access_chk() which cannot access the card in HS200/HS400 mode and which is in turn called by saveenv if env is in the MMC.
In such case, forcing the card clock to legacy frequency cannot work. Instead, the card must be switched to HS mode first, from which it can then be reprogrammed as needed.
However, this procedure needs additional code changes, since the current implementation checks whether the card correctly switched to HS mode in mmc_set_card_speed(). The check only expects that the card will be going to HS mode from lower modes, not from higher modes, hence add a parameter which indicates that the HS200/HS400 to HS downgrade is happening. This makes the code send the switch command first, reconfigure the controller next and finally perform the EXT_CSD readback check. The last two steps cannot be done in reverse order as the card is already in HS mode when the clock are being switched on the controller side.
Signed-off-by: Marek Vasut marek.vasut+renesas@gmail.com Cc: Jaehoon Chung jh80.chung@samsung.com
Applied to u-boot/master, thanks!