[PATCH 07/11] drm/i915: Clarify irq_lock locking, irq handlers

[Chris Wilson]

On Tue, Sep 16, 2014 at 12:28:18PM +0200, Daniel Vetter wrote:
> On Tue, Sep 16, 2014 at 11:21:52AM +0100, Chris Wilson wrote:
> > On Mon, Sep 15, 2014 at 02:35:07PM +0200, Daniel Vetter wrote:
> > > irq handlers always run with interrupts locally disabled, so
> > > plain spinlocks is all we need. I've also reviewed again that they
> > > all follow the _irq_handler postfix convention.
> > 
> > Hmm, we still have the full irq dance inside the reg read/write macros,
> > which themselves should never be used from inside the irq handlers.
> > 
> > (Modulo the misgivings in execlists_irq_handler).
> 
> Hm, we still have the ACTHEAD hack to read somewhat coherent-ish seqnos.
> Dunno whether open-coding that would make sense really, and whether it's
> really beneficial to force register writes to never acquire forcewake from
> irq context. Definitely material for different patches though.

ATCHD inside the irq handler? I am pretty sure that even -nightly doesn't
have the irq-barrier inside the irq handler.  And yes, we do want to
avoid having a massive delay whilst we apply the forcewake workarounds
from inside irq handlers.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre