On Tue, Jul 03, 2012 at 03:57:31PM -0300, Paulo Zanoni wrote:
> From: Paulo Zanoni <paulo.r.zanoni at intel.com>
>
> And rely on the fact that it's 0 to assume that machines without a PCH
> will have PCH_NONE as dev_priv->pch_type.
>
> Just today I finally realized that HAS_PCH_IBX is true for machines
> without a PCH. IMHO this is totally counter-intuitive and I don't
> think it's a good idea to assume that we're going to check for
> HAS_PCH_IBX only after we check for HAS_PCH_SPLIT.
>
> I believe that in the future we'll have more PCH types and checks
> like:
>
> if (HAS_PCH_IBX(dev) || HAS_PCH_CPT(dev))
>
> will become more and more common. There's a good chance that we may
> break non-PCH machines by adding these checks in code that runs on all
> machines. I also believe that the HAS_PCH_SPLIT check will become less
> common as we add more and more different PCH types.
>
> Also: are we sure we don't already have any bugs triggered by checking
> for HAS_PCH_IBX on non-PCH machines?
I think most of the HAS_PCH_xxx are implicitly guarded because we've split
up the pch modeset into it's own functions. I think there might only be a
few issues in the encoder functions maybe. Have your checked all the
HAS_PCH_IBX checks there? If you want, I can go through the code, too.
Otherwise I really like this.
-Daniel
>
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
> ---
> drivers/gpu/drm/i915/i915_drv.h | 1 +
> 1 file changed, 1 insertion(+)
>
> Another alternative would have been to change HAS_PCH_IBX to also
> check for HAS_PCH_SPLIT, but I'm not exactly in favor of adding more
> conditionals...
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index b7a1eaa..b12e79a 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -333,6 +333,7 @@ enum no_fbc_reason {
> };
>
> enum intel_pch {
> + PCH_NONE = 0, /* No PCH present */
> PCH_IBX, /* Ibexpeak PCH */
> PCH_CPT, /* Cougarpoint PCH */
> PCH_LPT, /* Lynxpoint PCH */
> --
> 1.7.10.2
>
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--
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48
