On Sat, Jan 16, 2021 at 7:04 PM Marek Vasut <marex@xxxxxxx> wrote: > Add support for testing whether bus voltage level translator is present > and operational. This is useful on systems where the bus voltage level > translator is optional, as the translator can be auto-detected by the > driver and the feedback clock functionality can be disabled if it is > not present. > > This requires additional pinmux state, "init", where the CMD, CK, CKIN > lines are not configured, so they can be claimed as GPIOs early on in > probe(). The translator test sets CMD high to avoid interfering with a > card, and then verifies whether signal set on CK is detected on CKIN. > If the signal is detected, translator is present, otherwise the CKIN > feedback clock are disabled. > > Signed-off-by: Marek Vasut <marex@xxxxxxx> > Cc: Alexandre Torgue <alexandre.torgue@xxxxxx> > Cc: Linus Walleij <linus.walleij@xxxxxxxxxx> > Cc: Ludovic Barre <ludovic.barre@xxxxxx> > Cc: Ulf Hansson <ulf.hansson@xxxxxxxxxx> > Cc: linux-stm32@xxxxxxxxxxxxxxxxxxxxxxxxxxxx Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx> Yours, Linus Walleij
