[Intel-gfx] [PATCH 1/2] drm/i915: Introduce INTEL_GEN_MASK

[Tvrtko Ursulin]

On 08/09/2017 10:39, Jani Nikula wrote:
> On Fri, 08 Sep 2017, Joonas Lahtinen <joonas.lahtinen at linux.intel.com> wrote:
>> Split INTEL_GEN_MASK out of IS_GEN macro, and make it usable
>> within static declarations (unlike combound statements).
>>
>> Cc: Jani Nikula <jani.nikula at intel.com>
>> Cc: Chris Wilson <chris at chris-wilson.co.uk>
>> Signed-off-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
>> ---
>>   drivers/gpu/drm/i915/i915_drv.h | 22 ++++++++++------------
>>   1 file changed, 10 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
>> index 63ca2ffcafef..c3f9d7d7b146 100644
>> --- a/drivers/gpu/drm/i915/i915_drv.h
>> +++ b/drivers/gpu/drm/i915/i915_drv.h
>> @@ -2873,23 +2873,21 @@ intel_info(const struct drm_i915_private *dev_priv)
>>   #define INTEL_REVID(dev_priv)	((dev_priv)->drm.pdev->revision)
>>   
>>   #define GEN_FOREVER (0)
>> +
>> +#define INTEL_GEN_MASK(s, e) ( \
>> +        BUILD_BUG_ON_ZERO(!__builtin_constant_p(s)) + \
>> +        BUILD_BUG_ON_ZERO(!__builtin_constant_p(e)) + \
>> +        GENMASK((e) != GEN_FOREVER ? (e) - 1 : BITS_PER_LONG - 1, \
>> +	        (s) != GEN_FOREVER ? (s) - 1 : 0) \
> 
> Reviewed-by: Jani Nikula <jani.nikula at intel.com>
> 
> but I'd really like a patch on top to remove the -1 from here and
> info->gen_mask.

What is the objection on -1? It is hidden in the macros so you can only 
see it if looking at disassembly or even lower level.

We could even make it -2, but AFAIR Chris wanted to keep the option for 
supporting gen1 open. :)

Regards,

Tvrtko