Re: [EXTERNAL] Re: wlcore getting stuck on hikey after the runtime PM autosuspend support change

[Tony Lindgren <tony@atomide.com>]

* Ricardo Salveti <rsalveti@rsalveti.net> [181214 12:42]:
> Hi,
> 
> On Thu, Dec 13, 2018 at 12:45 PM Tony Lindgren <tony@atomide.com> wrote:
> > * Ricardo Salveti <rsalveti@rsalveti.net> [181213 13:53]:
> > > I tried just increasing WL1271_PRE_POWER_ON_SLEEP from 20ms to 50ms
> > > (which gets used before calling wl12xx_sdio_power_on), and that was
> > > already enough to fix my issues on both hikey and beaglebone black
> > > wireless.
> >
> > OK good to hear that helps :)
> >
> > > Should we define another pre power on sleep specifically for the sdio
> > > case (and use directly in wl12xx_sdio_power_on)?
> >
> > I'd probably prefer to just increase WL1271_PRE_POWER_ON_SLEEP,
> > chances are the same delay is needed in all cases.
> 
> Investigating this issue a bit more, I noticed that the hang happens
> when PM decides to not suspend the device when doing an if down/up
> cycle.
> 
> Basically since commit 60f36637bbbd ("wlcore: sdio: allow pm to handle
> sdio power") PM is now handling the sdio power off/on process, and if
> wl12xx_sdio_power_on gets called right after wl12xx_sdio_power_off (if
> down/up), the device will not go to the required power off/on sequence
> (since PM will abort the suspend process), and the firmware loading
> process will fail. I would guess the problem only happens with
> autosuspend because of the extra delay it causes (pm_runtime_put
> always returns -EBUSY on wl12xx_sdio_power_off with autosuspend).

OK thanks for the update, that's interesting.

> Is there a way to force the suspend on wl12xx_sdio_power_off, or
> should we partially restore the old behavior?

Well usually we could do pm_runtime_put_sync_suspend() but
here it won't help as the pm_runtime_put() is already in
progress by the SDIO subsystem and that's why we get -EBUSY.

Does adding a little wait at the end of wl12xx_sdio_power_off()
before return? Maybe something like:

	/* Make sure the card gets powered off */
	while (error == -EBUSY && !pm_runtime_suspended(&card->dev) &&
		retries--) {
		msleep(100);
	}

Regards,

Tony