On Tue, 27 Aug 2019 10:10:43 +0200 Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: > The OCR register defines the supported range of VDD voltages for SD > cards. However, it has turned out that some SD cards reports an > invalid voltage range, for example having bit7 set. > > When a host supports MMC_CAP2_FULL_PWR_CYCLE and some of the voltages > from the invalid VDD range, this triggers the core to run a power > cycle of the card to try to initialize it at the lowest common > supported voltage. Obviously this fails, since the card can't support > it. > > Let's fix this problem, by clearing invalid bits from the read OCR > register for SD cards, before proceeding with the VDD voltage > negotiation. > > Cc: stable@xxxxxxxxxxxxxxx > Reported-by: Philip Langdale <philipl@xxxxxxxxx> > Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> > --- > drivers/mmc/core/sd.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c > index d681e8aaca83..fe914ff5f5d6 100644 > --- a/drivers/mmc/core/sd.c > +++ b/drivers/mmc/core/sd.c > @@ -1292,6 +1292,12 @@ int mmc_attach_sd(struct mmc_host *host) > goto err; > } > > + /* > + * Some SD cards claims an out of spec VDD voltage range. > Let's treat > + * these bits as being in-valid and especially also bit7. > + */ > + ocr &= ~0x7FFF; > + > rocr = mmc_select_voltage(host, ocr); > > /* Looks right. Tried it out and worked as expected. Reviewed-by: Philip Langdale <philipl@xxxxxxxxx> --phil
