[Nouveau] [RFC] Remove AGP support from Radeon/Nouveau/TTM

[Thomas Zimmermann]

Hi Alex

Am 12.05.20 um 20:32 schrieb Alex Deucher:
> On Tue, May 12, 2020 at 2:29 PM Thomas Zimmermann <tzimmermann at suse.de> wrote:
>>
>> Hi
>>
>> Am 11.05.20 um 19:17 schrieb Christian König:
>>> Hi guys,
>>>
>>> Well let's face it AGP is a total headache to maintain and dead for at least 10+ years.
>>>
>>> We have a lot of x86 specific stuff in the architecture independent graphics memory management to get the caching right, abusing the DMA API on multiple occasions, need to distinct between AGP and driver specific page tables etc etc...
>>>
>>> So the idea here is to just go ahead and remove the support from Radeon and Nouveau and then drop the necessary code from TTM.
>>>
>>> For Radeon this means that we just switch over to the driver specific page tables and everything should more or less continue to work.
>>>
>>> For Nouveau I'm not 100% sure, but from the code it of hand looks like we can do it similar to Radeon.
>>>
>>> Please comment what you think about this.
>>
>> There's some AGP support code in the DRM core. Can some of that declared
>> as legacy?
>>
>> Specifically, what about these AGP-related ioctl calls? Can they be
>> declared as legacy? It would appear to me that KMS-based drivers don't
>> have to manage AGP by themselves. (?)
> 
> The old drm core AGP code is mainly (only?) for the non-KMS drivers.
> E.g., mach64, r128, sis, savage, etc.

Exactly my point. There's one drm_agp_init() call left in radeon. The
rest of the AGP code is apparently for legacy non-KMS drivers. Should
the related ioctl calls be declared as legacy (i.e., listed with
DRM_LEGACY_IOCTL_DEF instead of DRM_IOCTL_DEF)? If so, much of the AGP
core code could probably be moved behind CONFIG_DRM_LEGACY as well.

Best regards
Thomas

> 
> Alex
> 
>>
>> Best regards
>> Thomas
>>
>>>
>>> Regards,
>>> Christian.
>>>
>>>
>>> _______________________________________________
>>> Nouveau mailing list
>>> Nouveau at lists.freedesktop.org
>>> https://lists.freedesktop.org/mailman/listinfo/nouveau
>>>
>>
>> --
>> Thomas Zimmermann
>> Graphics Driver Developer
>> SUSE Software Solutions Germany GmbH
>> Maxfeldstr. 5, 90409 Nürnberg, Germany
>> (HRB 36809, AG Nürnberg)
>> Geschäftsführer: Felix Imendörffer
>>
>> _______________________________________________
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>> amd-gfx at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/amd-gfx

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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