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From:   Jani Nikula <jani.nikula@linux.intel.com>
To:     Sam Ravnborg <sam@ravnborg.org>,
        Javier Martinez Canillas <javierm@redhat.com>
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        Dave Airlie <airlied@redhat.com>,
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Subject: Re: [PATCH v2 1/2] drm: Add a drm_drv_enabled() to check if drivers should be enabled
In-Reply-To: <YYQ0doL/F3ULjXyr@ravnborg.org>
Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
References: <20211104160707.1407052-1-javierm@redhat.com> <20211104160707.1407052-2-javierm@redhat.com> <YYQaYsCr+piMlRpS@ravnborg.org> <87r1bvajna.fsf@intel.com> <eddff405-18f5-31cf-9981-27343384e12c@redhat.com> <YYQ0doL/F3ULjXyr@ravnborg.org>
Date:   Thu, 04 Nov 2021 21:54:32 +0200
Message-ID: <87lf23ae87.fsf@intel.com>
MIME-Version: 1.0
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On Thu, 04 Nov 2021, Sam Ravnborg <sam@ravnborg.org> wrote:
> Hi Javier,
>
>> 
>> >>>  
>> >>> -	if (vgacon_text_force() && i915_modparams.modeset == -1)
>> >>> +	ret = drm_drv_enabled(&driver);
>> >>
>> >> You pass the local driver variable here - which looks wrong as this is
>> >> not the same as the driver variable declared in another file.
>> >
>> 
>> Yes, Jani mentioned it already. I got confused and thought that the driver
>> variable was also defined in the same compilation unit...
>> 
>> Maybe I could squash the following change?
>> 
>> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
>> index b18a250e5d2e..b8f399b76363 100644
>> --- a/drivers/gpu/drm/i915/i915_drv.c
>> +++ b/drivers/gpu/drm/i915/i915_drv.c
>> @@ -89,7 +89,7 @@
>>  #include "intel_region_ttm.h"
>>  #include "vlv_suspend.h"
>>  
>> -static const struct drm_driver driver;
>> +const struct drm_driver driver;
> No, variables with such a generic name will clash.
>
> Just add a
> const drm_driver * i915_drm_driver(void)
> {
> 	return &driver;
> }
>
> And then use this function to access the drm_driver variable.

Agreed on the general principle of exposing interfaces over data.

But... why? I'm still at a loss what problem this solves. We pass
&driver to exactly one place, devm_drm_dev_alloc(), and it's neatly
hidden away.


BR,
Jani.


-- 
Jani Nikula, Intel Open Source Graphics Center