Re: [RESEND PATCH V12 XDMA 1/2] dmaengine: xilinx: xdma: Add xilinx xdma driver

[Lizhi Hou]

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@xxxxxxxxxx> 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@xxxxxxxxxx/ 
> >
> > 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