Re: Include ASPEED ast-drm 1.15.1 video driver in kernel tree

[Jocelyn Falempe <jfalempe@redhat.com>]

On 13/02/2025 10:27, Nicolas Baranger wrote:
> Dear Thomas
> 
> Thanks for answer and help.
> 
> Yes, due to .date total removal in linux 6.14 (https://github.com/ 
> torvalds/linux/commit/cb2e1c2136f71618142557ceca3a8802e87a44cd <https:// 
> github.com/torvalds/linux/commit/ 
> cb2e1c2136f71618142557ceca3a8802e87a44cd>) the last DKMS sources are :
> https://xba.soartist.net/ast-drm_nba_20250211/nba-dkms/ 
> nba_last_src_20250212/src/ <https://xba.soartist.net/ast- 
> drm_nba_20250211/nba-dkms/nba_last_src_20250212/src/>
> 
> You can also find this sources in directory drivers/gpu/drm/ast_new of 
> the tarball https://xba.soartist.net/ast-drm_nba_20250211/nba-kernel/ 
> linux-6.14.0.1-ast1.15.1-rc2_nba0_20250212.tar.gz <https:// 
> xba.soartist.net/ast-drm_nba_20250211/nba-kernel/linux-6.14.0.1- 
> ast1.15.1-rc2_nba0_20250212.tar.gz>
> 
> I'm surprised by the fact the in-kernel driver 0.1.0 is more advanced 
> than Aspeed version 1.15.1 because on my system it has very poor 
> rendering and is very slow, twinkle is high and had poor colors.
> The screen flickering is high and it's like if I was using a very old 
> cathode ray tube monitor (In fact I'm using a SAMSUNG LCD monitor which 
> is perfectly functionnal and which display a nice and eyes confortable 
> picture when using ast 1.15.1 driver or the video output of the Nvidia 
> GPU ).
> 
> 
> My testing system is a test Xeon server with an AST2400 BMC with its AST 
> VGA card as the main video output (to be able to have a screen on the 
> BMC KVM) +a discrete NVIDIA GPU I'm using for GPGPU and 3D rendering 
> with Nvidia prime render offload.
> What I constat with embed kernel driver 0.1.0 is that the Xeon processor 
> is doing the video job for example when watching a video, and it's not 
> the case with version 1.15.1 even when displaying on the AST VGA card a 
> vulkan rotating cube (compute by nvidia GPU with nvidia prime but 
> display by the AST VGA card of the AST2400).
> Note that with in-kernel version 0.1.0 it's nearly impossible to make 
> round the vulkan cube at more than half a round by  second where it's 
> working (very) fine for a 32MB video memory card with version 1.15.1 as 
> you can see in the video present in the online directory
> 
> I'm not developer or kernel developer so be sure that I wouldn't have 
> done all this work if the in-kernel ast version 0.1.0 was usable out-of- 
> the-box
> 
> Sure you can give me a patch I will test on this server (building 
> mainline+ast_new yesterday tooks 19 minutes on this server)
> 
> PS:
> here is a 'git diff linux-6.14.0.1-ast-rc2/drivers/gpu/drm/ast 
> linux-6.14.0.1-ast-rc2/drivers/gpu/drm/ast_new'
> https://xba.soartist.net/ast-drm_nba_20250211/nba-dump/ast- 
> fullpatch.patch <https://xba.soartist.net/ast-drm_nba_20250211/nba-dump/ 
> ast-fullpatch.patch>
> Diff is about 250+ kb so the 2 drivers seems to have nothing to do with 
> each others...
> 
> Thanks again for help
> 
> Kind regards
> Nicolas
> 
> 
> Le 2025-02-13 08:57, Thomas Zimmermann a écrit :
> 
>> Hi Nicolas
>>
>> Am 12.02.25 um 19:58 schrieb Nicolas Baranger:
>>> Dear maintener
>>
>> That's mostly me and Jocelyn.
>>
>>>
>>> I did include ast-drm driver version 1.15.1 (in replacement of 
>>> version 0.1.0) on the new mainline kernel too (6.14.0-rc2) and I 
>>> issue a new dkms patch
>>>
>>> Last DKMS patch had been sucessfully tested on mainline.
>>> And last ast.ko version 1.15.1 included in linux tree had also been 
>>> sucessfully tested
>>>
>>> Online directory is updated with :
>>> - new DKMS patch
>>> - new DKMS srouces
>>> - new DKMS debian package
>>> - new tarball of mainline included ast_new ported in kernel tree
>>> - new kernel debian package (mainline with ast_new)
>>>
>>>
>>> NB: online directory is here: https://xba.soartist.net/ast- 
>>> drm_nba_20250211/ <https://xba.soartist.net/ast-drm_nba_20250211/>
>>>
>>> Please let me know what I should do to see this change in linux-next
>>
>> I'm having a little trouble with figuring out which of the many driver 
>> sources is the relevant one. Am I correct to assume it's the one at
>>
>> https://xba.soartist.net/ast-drm_nba_20250211/nba-dkms/ 
>> nba_last_src_20250212/src/ <https://xba.soartist.net/ast- 
>> drm_nba_20250211/nba-dkms/nba_last_src_20250212/src/>
>>
>>
>> About that driver: Although the official driver reports an ancient 
>> version number, it is an up-to-date driver. It is actually more up-to- 
>> date than Aspeed's package. Both drivers share source code and a few 
>> years ago there was an effort to bring the kernel's driver up to the 
>> same feature set. Since then, the kernel's driver has been updated, 
>> reworked and improved.
>>
>> About the performance: From what I can tell, the only significant 
>> difference in these drivers is memory management. Your ast_new driver 
>> uses an older algorithm that we replaced quite a few releases ago. The 
>> old version was unreliable on systems with little video memory, so we 
>> had to replace it.  I don't know why the new code should be slower though.

Regarding the performances of ast driver, I remember doing profiling 
some times ago, and when running glxgears (with llvmpipe), 65% of the 
CPU time was wasted in page fault 
(https://elixir.bootlin.com/linux/v6.13.2/source/drivers/gpu/drm/drm_gem_shmem_helper.c#L534)
But as this driver is mostly used for console/basic desktop usage, I 
didn't investigate more.

If I remember correctly, the switch to shmem, is because some devices 
have only 16MB of memory, and 1920x1200x32bits takes ~9MB, so it's not 
possible to have double buffering in this case. (And this is required by 
most desktop environment).

The switch to shmem was done with "f2fa5a99ca81c drm/ast: Convert ast to 
SHMEM", and introduced in v6.2. So maybe if you can try with a v6.1 
kernel, using the built-in ast driver and report if it has better 
performances.

Best regards,

-- 

Jocelyn

>>
>> If I give you a patch against a recent Linux kernel, are you capable 
>> of building the patched kernel and testing that change on your system?
>>
>> Best regards
>> Thomas
>>
>>
>>>
>>> Thanks for help
>>>
>>> Kind regards
>>> Nicolas Baranger
>>>
>>>
>>> Le 2025-02-11 19:15, Nicolas Baranger a écrit :
>>>
>>>> Dear maintener
>>>>
>>>> For my own usage, I did make work the ASPEED ast-drm 1.15.1 video 
>>>> driver on mainline kernel (6.13.0 + 6.13.1).
>>>>
>>>> ASPEED video driver is availiable here:
>>>> https://www.aspeedtech.com/file/support/Linux_DRM_1.15.1_4.tar.gz 
>>>> <https://www.aspeedtech.com/file/support/Linux_DRM_1.15.1_4.tar.gz>
>>>>
>>>> But it only work for LTS kernel
>>>> So I modify the DKMS package and I build a new Debian DKMS package 
>>>> with the adapted  source.
>>>> My patch can be find here :
>>>> https://xba.soartist.net/ast-drm_nba_20250211/nba-dkms/astdiff.patch 
>>>> <https://xba.soartist.net/ast-drm_nba_20250211/nba-dkms/astdiff.patch>
>>>> See the README:
>>>> https://xba.soartist.net/ast-drm_nba_20250211/nba-dkms/README 
>>>> <https://xba.soartist.net/ast-drm_nba_20250211/nba-dkms/README>
>>>>
>>>> Using this new 'ast 1.15.1' driver, performance are amazing compared 
>>>> to the 'ast' driver include in kernel tree, specially when using a 
>>>> discrete GPU and offloading VULKAN / 3D on it but using AST VGA card 
>>>> as the main video card and as the main and only video output (the 
>>>> discrete GPU is used only for offloading 3D or for cuda/opencl)
>>>>
>>>> So to make things easier, I include the new 'ast 1.15.1' driver in 
>>>> kernel tree as AST_NEW : linux-6.13.1-ast/drivers/gpu/drm/ast_new'
>>>> It's working fine as you can see on this video :
>>>> https://xba.soartist.net/ast-drm_nba_20250211/ 
>>>> vulcan_nvidia_prime_render_offload_on_ast_vga_card.webm <https:// 
>>>> xba.soartist.net/ast-drm_nba_20250211/ 
>>>> vulcan_nvidia_prime_render_offload_on_ast_vga_card.webm> I upload 
>>>> all the work I've done here :
>>>> https://xba.soartist.net/ast-drm_nba_20250211/ <https:// 
>>>> xba.soartist.net/ast-drm_nba_20250211/>
>>>>
>>>> See the global README :
>>>> https://xba.soartist.net/ast-drm_nba_20250211/README <https:// 
>>>> xba.soartist.net/ast-drm_nba_20250211/README>
>>>>
>>>> and the README in nba-kernel sub-directory :
>>>> https://xba.soartist.net/ast-drm_nba_20250211/nba-kernel/README 
>>>> <https://xba.soartist.net/ast-drm_nba_20250211/nba-kernel/README>
>>>>
>>>> I'm not a developer so please let me know if I made the things the 
>>>> right way and if this new 'ast 1.15.1' driver can be ported to 
>>>> linux-next or linux-? ?
>>>> If you need more explanations, do not hesitate to contact me, I 
>>>> would be happy to help
>>>>
>>>> Kind regards
>>>> Nicolas Baranger