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@vger.kernel.org Reported-by: Philip Langdale philipl@overt.org Signed-off-by: Ulf Hansson ulf.hansson@linaro.org --- 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);
/*