Thread (24 messages) 24 messages, 7 authors, 2019-09-27

Re: [PATCH v5 0/4] Raspberry Pi 4 DMA addressing support

From: Stefan Wahren <wahrenst@gmx.net>
Date: 2019-09-16 19:20:10
Also in: lkml

Hi Matthias,

[drop uninvolved receiver]

Am 13.09.19 um 12:39 schrieb Matthias Brugger:
quoted
quoted
quoted
quoted
 If you talk about the
downstream kernel, I suppose you mean we should change this in the FW DT blob
and in the downstream kernel. That would work for me.

Did I understand you correctly?
Yes

So i suggest to add the upstream compatibles into the repo mentioned above.

Sorry, but in case you decided as a U-Boot developer to be compatible
with a unreviewed DT, we also need to make U-Boot compatible with
upstream and downstream DT blobs.
Well RPi3 is working with the DT blob provided by the FW, as I mentioned earlier
if we can use this DTB we can work towards one binary that can boot both RPi3
and RPi4. On the other hand we can rely on the FW to detect the amount of memory
our RPi4 has.

That said, I agree that we should make sure that U-Boot can boot with both DTBs,
the upstream one and the downstream. Now the question is how to get to this. I'm
a bit puzzled that by talking about "unreviewed DT" you insinuate that bcm2711
compatible is already reviewed and can't be changed. From what I can see none of
these compatibles got merged for now, so we are still at time to change them.
Stephen Boyd was okay with clk changes except of a small nit. So i fixed
this is as he suggested in a separate series. Unfortunately this hasn't
be applied yet [1].

The i2c, pinctrl and the sdhci changes has been applied yet.

In my opinion it isn't the job of the mainline kernel to adapt to a
vendor device tree. It's the vendor device tree which needs to be fixed.
I agree with that. But if we can make this easier by choosing a compatible which
fits downstream without violating upstream and it makes sense with the naming
scheme of the RPi, I think that's a good argument.
i spend a lot of my spare time to prepare these patch series in order to
get a clean solution.

Either mixing bcm2711/bcm2838 or changing everything to bcm2838 in the
upstream tree has the following drawbacks:

- additional review time and delay of the Raspberry Pi 4 support
- harder to understand for developer/reviewer without RPi knowledge

Btw currently u-boot only uses bcm2711, so it would be nice to keep that.

So my suggestion is to add bcm2711 compatibles in the downstream tree.

Best regards
Stefan
quoted
Sorry, but this is my holiday. I will back after the weekend.
Sure, enjoy. I'll be on travel for the next two weeks but will try to keep up
with emails.

Regards,
Matthias
quoted
Best regards
Stefan

[1] - https://www.spinics.net/lists/linux-clk/msg40534.html
quoted
Apart from the point Florian made, to stay consistent with the RPi SoC naming,
it will save us work, both in the kernel and in U-Boot, as we would need to add
both compatibles to the code-base.

Regards,
Matthias
quoted
quoted
quoted
quoted
Regards,
Matthias
quoted
Regards,
Matthias
quoted
Are there any config.txt tweaks necessary?
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help