Re: [PATCH 1/2] drm/i915: Introduce INTEL_GEN_RANGE macro

From: Jani Nikula <jani.nikula@linux.intel.com>
To: Dave Gordon <david.s.gordon@intel.com>,
	Chris Wilson <chris@chris-wilson.co.uk>,
	Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
	Intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 1/2] drm/i915: Introduce INTEL_GEN_RANGE macro
Date: Mon, 09 May 2016 17:40:39 +0300	[thread overview]
Message-ID: <87oa8fi9aw.fsf@intel.com> (raw)
In-Reply-To: <57309E01.8070007@intel.com>

On Mon, 09 May 2016, Dave Gordon <david.s.gordon@intel.com> wrote:
> On 09/05/16 13:32, Jani Nikula wrote:
>> On Fri, 06 May 2016, Dave Gordon <david.s.gordon@intel.com> wrote:
>>> On 06/05/16 15:33, Chris Wilson wrote:
>>>> On Fri, May 06, 2016 at 03:16:25PM +0100, Tvrtko Ursulin wrote:
>>>>> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>>>>>
>>>>> To be used for more efficient Gen range checking.
>>>>>
>>>>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>>>>> ---
>>>>>    drivers/gpu/drm/i915/i915_drv.h         |  1 +
>>>>>    drivers/gpu/drm/i915/intel_fbc.c        |  2 +-
>>>>>    drivers/gpu/drm/i915/intel_ringbuffer.c | 12 ++++++------
>>>>>    3 files changed, 8 insertions(+), 7 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
>>>>> index 15fcbcece13c..935e381407ba 100644
>>>>> --- a/drivers/gpu/drm/i915/i915_drv.h
>>>>> +++ b/drivers/gpu/drm/i915/i915_drv.h
>>>>> @@ -2518,6 +2518,7 @@ struct drm_i915_cmd_table {
>>>>>    })
>>>>>    #define INTEL_INFO(p) 	(&__I915__(p)->info)
>>>>>    #define INTEL_GEN(p)	(INTEL_INFO(p)->gen)
>>>>> +#define INTEL_GEN_RANGE(p, s, e) (INTEL_INFO(p)->gen_mask & GENMASK(e, s))
>>>>>    #define INTEL_DEVID(p)	(INTEL_INFO(p)->device_id)
>>>>>    #define INTEL_REVID(p)	(__I915__(p)->dev->pdev->revision)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
>>>>> index d5a7cfec589b..2c3681757aba 100644
>>>>> --- a/drivers/gpu/drm/i915/intel_fbc.c
>>>>> +++ b/drivers/gpu/drm/i915/intel_fbc.c
>>>>> @@ -740,7 +740,7 @@ static void intel_fbc_update_state_cache(struct intel_crtc *crtc)
>>>>>
>>>>>    	/* FIXME: We lack the proper locking here, so only run this on the
>>>>>    	 * platforms that need. */
>>>>> -	if (INTEL_INFO(dev_priv)->gen >= 5 && INTEL_INFO(dev_priv)->gen < 7)
>>>>> +	if (INTEL_GEN_RANGE(dev_priv, 5, 6))
>>>>>    		cache->fb.ilk_ggtt_offset = i915_gem_obj_ggtt_offset(obj);
>>>>>    	cache->fb.pixel_format = fb->pixel_format;
>>>>>    	cache->fb.stride = fb->pitches[0];
>>>>> @@ -1241,12 +1241,12 @@ static int init_render_ring(struct intel_engine_cs *engine)
>>>>>    			   _MASKED_BIT_ENABLE(GFX_TLB_INVALIDATE_EXPLICIT));
>>>>>
>>>>>    	/* WaBCSVCSTlbInvalidationMode:ivb,vlv,hsw */
>>>>> -	if (IS_GEN7(dev))
>>>>> +	if (IS_GEN7(dev_priv))
>>>>>    		I915_WRITE(GFX_MODE_GEN7,
>>>>>    			   _MASKED_BIT_ENABLE(GFX_TLB_INVALIDATE_EXPLICIT) |
>>>>>    			   _MASKED_BIT_ENABLE(GFX_REPLAY_MODE));
>>>>>
>>>>> -	if (IS_GEN6(dev)) {
>>>>> +	if (IS_GEN6(dev_priv)) {
>>>>
>>>> This chunk shouldn't be in this patch.
>>>>
>>>> Couldn't improve upon INTEL_GEN_RANGE.
>>>>
>>>> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
>>>> -Chris
>>>
>>> INTEL_GEN_IN_RANGE() ?
>>>
>>> Perhaps emphasises that we're using INclusive ranges?
>>
>> Or just IS_GEN(p, since, until) similar to IS_SKL_REVID() and
>> IS_BXT_REVID(). Might as well make this shorter to write.
>>
>> BR,
>> Jani.
>
> We need a notation that will look good (and be efficient) for "before 
> GEN x" and "from GEN y on" (or "up to and including GEN p" and "after 
> GEN q") -- these make up the vast majority of tests on the GEN number.
>
> Also, we need real clarity on inclusion/exclusion. since..until notation 
> is perhaps ambiguous - in particular, is "until" included? English usage 
> is not clear here, it's often but not always exclusive!

If you want real clarity, you'll ditch this patch and use

	if (INTEL_GEN(p) >= 5 && INTEL_GEN(p) <= 7)
        	etc...

and be done with it. There's too much churn going on with all the
related macros anyway, so I'm not at all convinced about the patches
anyway.

J.

>
> .Dave.
>

-- 
Jani Nikula, Intel Open Source Technology Center
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