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SubjectRe: [RESEND PATCH V12 XDMA 1/2] dmaengine: xilinx: xdma: Add xilinx xdma driver
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On 2/21/23 13:46, Martin Tůma wrote:
> On 21. 02. 23 22:06, Geert Uytterhoeven wrote:
>> Hi Martin,
>>
>> On Tue, Feb 21, 2023 at 9:45 PM Martin Tůma <tumic@gpxsee.org> wrote:
>>> On 21. 02. 23 14:25, Geert Uytterhoeven wrote:
>>>> No platform dependencies at all, while this is a platform driver that
>>>> relies on some other not-yet-existing driver creating an "xdma"
>>>> platform device?
>>>
>>> There is at least one "already-existing" driver based on this driver
>>> that is waiting in the v4l2 queue for xdma - our MGB4 driver:
>>> https://patchwork.kernel.org/project/linux-media/patch/20230207150119.5542-2-tumic@gpxsee.org/
>>>
>>
>> Thanks for the link!
>>
>> As VIDEO_MGB4 selects XILINX_XDMA, perhaps XILINX_XDMA
>> can be made invisible, unless compile-testing?
>>
>>      config XILINX_XDMA
>>          tristate "Xilinx DMA/Bridge Subsystem DMA Engine" if
>> COMPILE_TEST
>>
>> Gr{oetje,eeting}s,
>>
>>                          Geert
>>
>
> Hi,
> I think that the XDMA driver will always be used by a superior PCIe
> card driver like in our case (mgb4) and using it separately makes no
> sense/is not possible, so disabling it until some of the superior
> drivers selects it makes sense for me. But what about out-of-the-tree
> modules based on xdma? Making the module "invisible" will make compile
> them much harder I guess? And there will be proprietary drivers based
> on xdma, see Xilinx XRT:
> https://github.com/houlz0507/XRT-1/tree/xdma_v4_usage
>
> The xdma authors from Xilinx will definitely give you a more
> authoritative answer. I'm just a "random" user of the xdma module.
> Originally our mgb4 driver was based on our own xdma sub-driver (in
> turn based on some old "test" driver from Xilinx) which I was glad we
> could abandon when this xdma driver has appeared. I helped the xdma
> module to become usable for PCIe cards like our v4l2 grabber, but the
> original intents of the xdma driver are unknown to me. If it is XRT,
> than Xilinx will probably like the module to stay visible.
>
> M.
>
There are PCIe devices which use the XDMA IP and would use this xdma
driver. Out of tree drivers for Xilinx/AMD Alveo devices can switch to
this in kernel xdma driver.


Thanks,

Lizhi

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