Re: [PATCH 2/2] drm/i915: Simplify i915_reg_read_ioctl

[Joonas Lahtinen <joonas.lahtinen@linux.intel.com>]

On Fri, 2017-09-08 at 15:24 +0300, Ville Syrjälä wrote:
> On Fri, Sep 08, 2017 at 12:29:35PM +0300, Joonas Lahtinen wrote:
> > @@ -1292,72 +1292,71 @@ void intel_uncore_fini(struct drm_i915_private *dev_priv)
> >  	intel_uncore_forcewake_reset(dev_priv, false);
> >  }
> >  
> > -#define GEN_RANGE(l, h) GENMASK((h) - 1, (l) - 1)
> > -
> > -static const struct register_whitelist {
> > -	i915_reg_t offset_ldw, offset_udw;
> > -	uint32_t size;
> > -	/* supported gens, 0x10 for 4, 0x30 for 4 and 5, etc. */
> > -	uint32_t gen_bitmask;
> > -} whitelist[] = {
> > -	{ .offset_ldw = RING_TIMESTAMP(RENDER_RING_BASE),
> > -	  .offset_udw = RING_TIMESTAMP_UDW(RENDER_RING_BASE),
> > -	  .size = 8, .gen_bitmask = GEN_RANGE(4, 10) },
> > -};
> > +static const struct reg_whitelist {
> > +	i915_reg_t offset_ldw;
> > +	i915_reg_t offset_udw;
> > +	unsigned long gen_mask;
> 
> 'long' seems like a bad type for something like this. Changes size on 32
> vs 64 bit. Also we could make do with 16 bits for now, though with
> the single whitelist entry this only has a small impact.

It's actually the type GCC wants because GENMASK is used internally to
produce the mask, otherwise it complained. We should likely use
unsigned long in dev_priv too, with a BUILD_BUG_ON(max_gen >
BITS_PER_LONG) check.

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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