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@xxxxxxxxxxxxxxx>
> Signed-off-by: Brian Norris <briannorris@xxxxxxxxxxxx>
> Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> Link: https://lore.kernel.org/r/20220914014010.2076169-1-briannorris@xxxxxxxxxxxx
> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
> ---
> Should also apply cleanly to 4.14.y and newer.
All now queued up.
greg k-h
