Re: [PATCH] mmc: tmio: Don't access hardware registers after stopping clocks

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Magnus,

On Tuesday 19 June 2012 15:53:30 Magnus Damm wrote:
> On Fri, Jun 15, 2012 at 4:09 PM, Guennadi Liakhovetski wrote:
> > On Fri, 15 Jun 2012, Magnus Damm wrote:
> > 
> > [snip]
> > 
> >> Guennadi, does this trigger on sh7372 as well? If not, why is that?
> > 
> > No. That message is produced by the sh_mobile_sdhi_wait_idle() function,
> > which is only used, if the TMIO_MMC_HAS_IDLE_WAIT flag is set, which is
> > not set on mackerel (or ap4evb).
> 
> Ok, thanks for checking this. It seems that we are "lucky" to find
> this breakage...
> 
> In the future, please take care to make sure this does not happen
> again. This goes without saying, but the driver should not access the
> hardware when it is Runtime PM suspended. I believe it should be
> possible to verify the code paths by manual code inspection. Also, to
> make the behavior more consistent you may want to make use of
> "pm_runtime_put_sync()" instead of "pm_runtime_put()".

For testing that's a good idea. That makes me wonder whether we should have a 
Kconfig option to turn all pm_runtime_put() into pm_runtime_put_sync() for 
stress-testing.

-- 
Regards,

Laurent Pinchart