On Fri, Oct 07, 2022 at 11:36:47AM -0700, Brian Norris wrote:
commit e9233917a7e53980664efbc565888163c0a33c3f upstream.
This loop intends to retry a max of 10 times, with some implicit termination based on the SD_{R,}OCR_S18A bit. Unfortunately, the termination condition depends on the value reported by the SD card (*rocr), which may or may not correctly reflect what we asked it to do.
Needless to say, it's not wise to rely on the card doing what we expect; we should at least terminate the loop regardless. So, check both the input and output values, so we ensure we will terminate regardless of the SD card behavior.
Note that SDIO learned a similar retry loop in commit 0797e5f1453b ("mmc: core: Fixup signal voltage switch"), but that used the 'ocr' result, and so the current pre-terminating condition looks like:
rocr & ocr & R4_18V_PRESENT(i.e., it doesn't have the same bug.)
This addresses a number of crash reports seen on ChromeOS that look like the following:
... // lots of repeated: ... <4>[13142.846061] mmc1: Skipping voltage switch <4>[13143.406087] mmc1: Skipping voltage switch <4>[13143.964724] mmc1: Skipping voltage switch <4>[13144.526089] mmc1: Skipping voltage switch <4>[13145.086088] mmc1: Skipping voltage switch <4>[13145.645941] mmc1: Skipping voltage switch <3>[13146.153969] INFO: task halt:30352 blocked for more than 122 seconds. ...Fixes: f2119df6b764 ("mmc: sd: add support for signal voltage switch procedure") Cc: stable@vger.kernel.org Signed-off-by: Brian Norris briannorris@chromium.org Reviewed-by: Guenter Roeck linux@roeck-us.net Link: https://lore.kernel.org/r/20220914014010.2076169-1-briannorris@chromium.org Signed-off-by: Ulf Hansson ulf.hansson@linaro.org
Should also apply cleanly to 4.14.y and newer.
All now queued up.
greg k-h