Skip to content
Commit 3ba555d8 authored by Brian Norris's avatar Brian Norris Committed by Greg Kroah-Hartman
Browse files

mmc: core: Terminate infinite loop in SD-UHS voltage switch

[ Upstream commit e9233917 ]

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 0797e5f1
("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: f2119df6

 ("mmc: sd: add support for signal voltage switch procedure")
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarBrian Norris <briannorris@chromium.org>
Reviewed-by: default avatarGuenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220914014010.2076169-1-briannorris@chromium.org
Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 06846583
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment