Re: [Intel-gfx] [PATCH 3/3] drm/i915/uncore: optimize CONFIG_DRM_I915_DEBUG_MMIO=n more

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 06/07/2023 13:06, Jani Nikula wrote:
> On Thu, 06 Jul 2023, Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com> wrote:
>> On 04/07/2023 10:48, Jani Nikula wrote:
>>> While the default for the mmio_debug parameter depends on
>>> CONFIG_DRM_I915_DEBUG_MMIO, we look it up and include all the code for
>>> unclaimed reg debugging even when CONFIG_DRM_I915_DEBUG_MMIO=n. Fix it.
>>>
>>> Cc: Lee Shawn C <shawn.c.lee@intel.com>
>>> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
>>> ---
>>>    drivers/gpu/drm/i915/intel_uncore.c | 3 ++-
>>>    1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
>>> index dfefad5a5fec..da2edde4b6f6 100644
>>> --- a/drivers/gpu/drm/i915/intel_uncore.c
>>> +++ b/drivers/gpu/drm/i915/intel_uncore.c
>>> @@ -1929,7 +1929,8 @@ static inline bool __must_check
>>>    unclaimed_reg_debug_header(struct intel_uncore *uncore,
>>>    			   const i915_reg_t reg, const bool read)
>>>    {
>>> -	if (likely(!uncore->i915->params.mmio_debug) || !uncore->debug)
>>> +	if (!IS_ENABLED(CONFIG_DRM_I915_DEBUG_MMIO) ||
>>> +	    likely(!uncore->i915->params.mmio_debug) || !uncore->debug)
>>>    		return false;
>>
>> But now it would not be possible to enable mmio_debug, if Kconfig
>> _default_ is 'n'. What am I missing?
> 
> You're not missing anything, I am. *facepalm*
> 
> The question is, are the first two acceptable without the third?

What are 1st, 2nd and 3rd in your counting?

This area is confusing me a little bit.

If I look at unclaimed_reg_debug it appears unclaimed register debug 
depends on mmio_debug.

But if I look at the message output by 
intel_uncore_arm_unclaimed_mmio_detection it appears that on detecting 
an unclaimed register we suggest to enable mmio_debug.

Isn't that a contradiction?

Regards,

Tvrtko