Re: [PATCH 3/4] arm64: dts: renesas: r8a7796: Add DU device to DT

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Magnus,

On Thursday 27 Oct 2016 16:25:35 Magnus Damm wrote:
> On Thu, Oct 27, 2016 at 4:13 PM, Simon Horman <horms@verge.net.au> wrote:
> > On Thu, Oct 27, 2016 at 03:52:44PM +0900, Magnus Damm wrote:
> >> On Thu, Oct 20, 2016 at 5:56 PM, Simon Horman <horms@verge.net.au> wrote:
> >>> On Tue, Oct 18, 2016 at 12:19:26PM +0300, Laurent Pinchart wrote:
> >>>> On Tuesday 18 Oct 2016 11:05:32 Geert Uytterhoeven wrote:
> >>>>> On Mon, Oct 17, 2016 at 11:34 PM, Laurent Pinchart wrote:
> >>>>>> Add the DU device to r8a7796.dtsi in a disabled state.
> >>>>>> 
> >>>>>> Signed-off-by: Laurent Pinchart
> >>>>>> <laurent.pinchart+renesas@ideasonboard.com>
> >>>>> 
> >>>>> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
> >>>> 
> >>>> Could you please pick patches 1/4 to 3/4 from this series and apply
> >>>> them to your tree ? For convenience I've pushed them to
> >>>> 
> >>>>       git://linuxtv.org/pinchartl/media.git drm/r8a7796/dt
> >>>> 
> >>>> along with patch "arm64: dts: renesas: r8a7795: Remove FCP
> >>>> SoC-specific compatible strings" that has been acked too. If you pull
> >>>> from that branch please make sure you skip the top-most patch "arm64:
> >>>> dts: renesas: r8a7796-salvator-x: Enable DU" for now.
> >>> 
> >>> Sure, done.
> >> 
> >> I think we should hold off with the upstreaming of the DU and VSP
> >> integration code for now. Sorry for noticing this late, but I thought
> >> we had already discussed the integration order and that merge of
> >> non-64-bit capable devices need to be put on hold.
> >> 
> >> In particular, not so much the DU device (this patch) but more the VSP
> >> instances. The reason for that is that VSP devices can only perform
> >> 32-bit bus mastering without IOMMU. I believe next step for all this
> >> would be to enable all on-board memory on r8a7796 Salvator-x, but I
> >> think Geert is working on that.
> > 
> > So you would like to see the following patches dropped?
> > 
> > ee73acb13978 arm64: dts: renesas: r8a7796: Add VSP instances
> > 0a6519d782fd arm64: dts: renesas: r8a7796: Add FCPF and FCPV instances
> 
> Yes, that would be great. Sorry for not noticing earlier.

I'm sorry, but I don't agree with that. First of all the FCP has no issue with 
>4GB memory as it doesn't perform DMA itself. Then, while the IPMMU is 
required to operate the VSP with >4GB memory, enabling the VSP instances won't 
break anything as unlike the DU the VSPs won't be used by standard kernel or 
userspace components.

-- 
Regards,

Laurent Pinchart