[PATCH v3 6/7] mmc: sunxi: Add runtime_pm support

On Thu, Jun 14, 2018 at 7:12 AM Marc Zyngier [off-list ref] wrote:

Hi Maxime,

On 16/04/18 15:23, Maxime Ripard wrote:

quoted

So far, even if our card was not in use, we didn't shut down our MMC
controller, which meant that it was still active and clocking the bus.

While this obviously means that we could save some power there, it also
creates issues when it comes to EMC control since we'll have a perfect peak
at the card clock rate.

Let's implement runtime_pm with autosuspend so that we will shut down the
controller when it's not been in use for quite some time.

[...]

This patch has the unfortunate impact of killing my A20 system
(cubietruck), as of 9a8e1e8cc2c02c57c4e941651a8481a633506c91:

kernelCI also found failures on a few a10/a20 platfforms[1], and they
all fail to reach userspace, similar to what Marc reported.

I bisected on a sun7i-a20-bananapi and that pointed at this commit
also (in mainline as 9a8e1e8cc2c0 mmc: sunxi: Add runtime_pm support)

Kevin

[1] https://kernelci.org/boot/all/job/mainline/branch/master/kernel/v4.17-11928-g2837461dbe6f/
[2] $ git bisect log
git bisect start
# good: [5037be168f0e4ee910602935b1180291082d3aac] Merge branch
'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
git bisect good 5037be168f0e4ee910602935b1180291082d3aac
# bad: [f60342fac9fae20ada2cd5faadbc2a1337cae03f] Merge tag
'mmc-v4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc
git bisect bad f60342fac9fae20ada2cd5faadbc2a1337cae03f
# good: [fd59ccc53062964007beda8787ffd9cd93968d63] Merge tag
'fscrypt_for_linus' of
git://git.kernel.org/pub/scm/linux/kernel/git/tytso/fscrypt
git bisect good fd59ccc53062964007beda8787ffd9cd93968d63
# good: [2158091d9cda6f126f71973667e8a9fc1e795d03] Merge branch
'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
git bisect good 2158091d9cda6f126f71973667e8a9fc1e795d03
# bad: [bfd694d5e21c2f0d344db6afeaf993bb0f299545] mmc: core: Add
tunable delay before detecting card after card is inserted
git bisect bad bfd694d5e21c2f0d344db6afeaf993bb0f299545
# good: [743b819e4178935e3f098e5f13db301f532fa9e0] mmc: sunxi: Reorder
the headers
git bisect good 743b819e4178935e3f098e5f13db301f532fa9e0
# bad: [ebca50dfae525341c48c2f69798667352318549e] mmc:
renesas_sdhi_internal_dmac: remove superfluous WARN
git bisect bad ebca50dfae525341c48c2f69798667352318549e
# bad: [eef797ac13c08fae0f0ce7d2215d0951e884fa2d] mmc: sunxi: Drop the
init / reset of the controller from set_ios
git bisect bad eef797ac13c08fae0f0ce7d2215d0951e884fa2d
# good: [ad04d9555da02c719de25b7d1e81ea8d0d2c4838] mmc: sunxi: Move
clock configuration to a function
git bisect good ad04d9555da02c719de25b7d1e81ea8d0d2c4838
# bad: [9a8e1e8cc2c02c57c4e941651a8481a633506c91] mmc: sunxi: Add
runtime_pm support
git bisect bad 9a8e1e8cc2c02c57c4e941651a8481a633506c91
# good: [e27e1f3d04061ccc3735361554088cd7aa286e31] mmc: sunxi: Move
the card power configuration to a function
git bisect good e27e1f3d04061ccc3735361554088cd7aa286e31
# first bad commit: [9a8e1e8cc2c02c57c4e941651a8481a633506c91] mmc:
sunxi: Add runtime_pm support