Re: [PATCH] mmc: sdhci-pci-gli: Disable LPM during initialization

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There's something happening in this driver that doesn't
make much sense to me.

According to the pm runtime docs [1] the initial runtime pm
status of all devices is 'suspended'. Which I presume, means:
if the driver doesn't use any of the pm_runtime_*() functions
to tell the core "actually, I am active after probe", then the
device remains suspended until explicitly going active, at which
point the runtime_resume() callback is invoked.

That's the theory. In practice, what do I see on a device
containing this bridge?
Intel SoC <-> PCIe bus <-> gl9763e bridge <-> eMMC bus <-> eMMC drive

at probe() (does not exist in this driver so I stubbed it):
[ 0.601542] runtime pm is enabled = 1 (disable_depth == 0)
[ 0.601552] runtime pm is active = 2 (usage_count)

at probe_slot():
[ 0.602024] runtime pm is enabled = 1
[ 0.602027] runtime pm is active = 2

At add_host():
[ 0.602804] runtime pm is enabled = 1
[ 0.602809] runtime pm is active = 3

It looks like:
- nowhere does the gl9763e driver inform runtime pm it's active
- the device is active in probe(), probe_slot() and add_host()
- the runtime_resume() callback did not get called before
probe(), probe_slot(), or add_host().

Why is the runtime_resume() callback not invoked?
Does the driver have a runtime_pm misconfiguration issue here?

Perhaps Rafael could clarify?


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