[PATCH v2] radeon: Use mdelay() instead of msleep() when we can't sleep in atom_op_delay().

[Daniel Vetter]

On Wed, Jan 04, 2012 at 01:28:28PM +0000, Alan Cox wrote:
> > unnusual contexts). I'm not sure whether your proposed instrumentation is
> > really worth it though - in i915-land we don't bother with this. But maybe
> 
> In i915 land it's specific code paths so effectively it is marked up. We
> don't do it for every random delay in all the connectors and other bits.
> The bits of code believing they are safe use sleeping locks and we'll get
> spewage if that breaks. Ditto at this point I hope gma500 although I
> would not be surpised to find ones I still need to fix from being mdelay.

The atomic context check is in the _wait_for macro in intel_drv.h which is
used all over the place. Like in the wait_for_vblank function. So I don't
think you can use i915.ko as a shiny beacon of how to do it ;-)

> > with the firmware provided and randomly b0rked atombios tables it might
> > make sense to add the WARN_ON_ONCE you've proposed in the other mail
> 
> I think we need it because it can be added by firmware, it could be
> silently done and the atombios paths cover so many different things
> beyond modesetting using that exact same function we need the mark up.
> 
> If some vendor puts a 100ms delay in a connector related hotplug check we
> are going to have a horrible time debugging 'bugzilla #zillion, 'poor
> performance in OpenGL game with Radeon foozillion'

Well, hotplug is alreay a giant pain because of the single lock to rule
them all design of the current kms code: Long delays already stall
everything else (well, cursor updates and pageflips) and we have tons of
bugreports that complain about it. In a sense your example undermines my
point that we have lower hanger fruit to fix all over the place already ...

But as I've said I like the WARN_ON you want to add, but otoh hand think
it shouldn't be used to stall the small&hackish fix of adding the relevant
in_atomic checks.
-Daniel
-- 
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48