Nouveau - May 2020 - [RFC] Remove AGP support from Radeon/Nouveau/TTM

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 K?nig:
> > 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.

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 N?rnberg, Germany
> (HRB 36809, AG N?rnberg)
> Gesch?ftsf?hrer: Felix Imend?rffer
>
> _______________________________________________
> amd-gfx mailing list
> amd-gfx at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/amd-gfx

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 K?nig:
>>> 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 N?rnberg, Germany
>> (HRB 36809, AG N?rnberg)
>> Gesch?ftsf?hrer: Felix Imend?rffer
>>
>> _______________________________________________
>> amd-gfx mailing list
>> 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 N?rnberg, Germany
(HRB 36809, AG N?rnberg)
Gesch?ftsf?hrer: Felix Imend?rffer

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On Tue, May 12, 2020 at 3:10 PM Thomas Zimmermann <tzimmermann at suse.de>
wrote:
>
> 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 K?nig:
> >>> 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.
Ah, I forgot about drm_agp_init().  I was just thinking the other AGP
stuff.  Yeah, I think we could make it legacy.

Alex

>
> 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 N?rnberg, Germany
> >> (HRB 36809, AG N?rnberg)
> >> Gesch?ftsf?hrer: Felix Imend?rffer
> >>
> >> _______________________________________________
> >> amd-gfx mailing list
> >> 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 N?rnberg, Germany
> (HRB 36809, AG N?rnberg)
> Gesch?ftsf?hrer: Felix Imend?rffer
>