[Intel-gfx] [PATCH 06/29] drm/i915: add support for SBI ops

[Eugeni Dodonov]

On Fri, Apr 13, 2012 at 17:26, Chris Wilson <chris at chris-wilson.co.uk>wrote:

> On Fri, 13 Apr 2012 17:08:42 -0300, Eugeni Dodonov <
> eugeni.dodonov at intel.com> wrote:
> > With Lynx Point, we need to use SBI to communicate with the display clock
> > control. This commit adds helper functions to access the registers via
> > SBI.
> >
> > v2: de-inline the function and address changes in bits names
> >
> > v3: protect operations with dpio_lock, increase timeout to 100 for
> > paranoia sake.
> >
> > v1 Reviewed-by: Rodrigo Vivi <rodrigo.vivi at gmail.com>
>
> Hmm, busy-waits upon a register change. Does it have to be atomic? Can
> it really be called in IRQ context? Can I have a sleepy version that
> won't cause audible stutters for the normal case? (Admittedly
> single-core processors are history...)
>

The original version wasn't atomic and wasn't called in IRQ context, but
Daniel suggested that I should be more paranoid about this so I followed
his idea :).

Anyway, both versions (this one and previous one) work; would both you and
Daniel be happy if I do another version of this keeping the dpio_lock
handling but dropping atomic bits?

-- 
Eugeni Dodonov
<http://eugeni.dodonov.net/>
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