[PATCH 0/3] NVIDIA Tegra210 NVJPG support

[Diogo Ivo]

Hi Mikko,

On 6/30/25 7:14 AM, Mikko Perttunen wrote:
> On 6/17/25 6:26 PM, Diogo Ivo wrote:
>>
>>
>> On 6/17/25 5:40 AM, Mikko Perttunen wrote:
>>>
>>>
>>> On 6/16/25 7:21 PM, Diogo Ivo wrote:
>>>>
>>>>
>>>> On 6/11/25 4:06 PM, Thierry Reding wrote:
>>>>> On Wed, Jun 11, 2025 at 01:05:40PM +0100, Diogo Ivo wrote:
>>>>>>
>>>>>>
>>>>>> On 6/10/25 10:52 AM, Mikko Perttunen wrote:
>>>>>>> On 6/10/25 6:05 PM, Thierry Reding wrote:
>>>>>>>> On Fri, Jun 06, 2025 at 11:45:33AM +0100, Diogo Ivo wrote:
>>>>>>>>> Hello,
>>>>>>>>>
>>>>>>>>> This series adds support for the NVJPG hardware accelerator 
>>>>>>>>> found in the
>>>>>>>>> Tegra210 SoC.
>>>>>>>>>
>>>>>>>>> The kernel driver is essentially a copy of the NVDEC driver as 
>>>>>>>>> both
>>>>>>>>> engines are Falcon-based.
>>>>>>>>>
>>>>>>>>> For the userspace part I have written a Mesa Gallium backend 
>>>>>>>>> [1] that,
>>>>>>>>> while still very much experimental, works in decoding images
>>>>>>>>> with VA- API.
>>>>>>>>>
>>>>>>>>> I have been using ffmpeg to call VA-API with the following 
>>>>>>>>> command:
>>>>>>>>>
>>>>>>>>> ffmpeg -v verbose -hwaccel vaapi -hwaccel_device
>>>>>>>>> /dev/dri/renderD129 -i <input.jpg> -pix_fmt bgra -f fbdev
>>>>>>>>> /dev/fb0
>>>>>>>>>
>>>>>>>>> which decodes <input.jpg> and shows the result in the framebuffer.
>>>>>>>>>
>>>>>>>>> The firmware for the engine can be obtained from a Linux for Tegra
>>>>>>>>> distribution.
>>>>>>>>
>>>>>>>> By the way, have you tried running this on anything newer than 
>>>>>>>> Tegra210?
>>>>>>>> Given your progress on this, we can probably start thinking about
>>>>>>>> submitting the binaries to linux-firmware.
>>>>>>>
>>>>>>> FWIW, the impression I have is that NVJPG is basically unchanged 
>>>>>>> all the
>>>>>>> way to Tegra234. So if we add stream ID support and the 
>>>>>>> firmwares, it'll
>>>>>>> probably just work. Tegra234 has the quirk that it has two 
>>>>>>> instances of
>>>>>>> NVJPG -- these have to be distinguished by their different class 
>>>>>>> IDs.
>>>>>>> But we should go ahead with the T210 support first.
>>>>>>
>>>>>> I have a question here, what exactly are the stream IDs? While 
>>>>>> working
>>>>>> on the driver this came up and I didn't manage to figure it out.
>>>>>
>>>>> Stream IDs are a way to identify memory transactions as belonging to a
>>>>> certain device. This comes into play when working with the IOMMU 
>>>>> (which
>>>>> is a Tegra SMMU on Tegra210 and earlier, and an ARM SMMU on Tegra) and
>>>>> is used to isolate DMA capable devices. Basically for every stream ID
>>>>> you get a separate I/O address space. NVJPG will have its own address
>>>>> space, and so will VIC. Each device can only access whatever has been
>>>>> mapped to it's I/O address space. That means NVJPG can't interfere 
>>>>> with
>>>>> VIC and vice-versa. And neither can any of these engines read from or
>>>>> write to random system memory if badly programmed.
>>>>
>>>> So if I understand this correctly a Stream ID corresponds to an IOMMU
>>>> domain right?
>>>
>>> Technically not necessarily, but in practice that's the case, as the 
>>> IOMMU driver creates IOMMU domains for each stream ID in the device 
>>> tree. They are similar to the SWGROUPs on Tegra210.
>>
>> Ok that makes sense, thank you for the clarification :)
>>
>>>> Ok, then in that case I'll keep the driver in its current state without
>>>> these implementations if that's ok. Connected with this I wanted to 
>>>> know
>>>> your thoughts on the best way to upstream this, is it better to wait 
>>>> for
>>>> testing on different platforms first and then if things work merge a
>>>> driver that works for all of them or go with Tegra210 first and then 
>>>> add
>>>> more platforms later on?
>>>
>>> Personally, I'd say to go for Tegra210 first.
>>
>> In that case I believe that in the v2 I sent out of the driver I 
>> addressed
>> both yours and Thierry's reviews and the driver should be in good 
>> condition
>> for Tegra210. What are the next steps in order to merge it?
> 
> I left one more comment on the v2 patch. With that fixed, if Thierry has 
> no further objections, hopefully he can merge.

I sent out v3 addressing this comment and picked up your Acked-by.

Thanks for the review!
Diogo

> Cheers,
> Mikko
> 
>>
>> Thanks,
>> Diogo
>>
>>> Cheers
>>> Mikko
>>
>