Re: [PATCH 2/4] dt-bindings: display: tegra: Add channel/syncpoint range properties

[Mikko Perttunen <mperttunen@nvidia.com>]

On Friday, June 26, 2026 7:26 PM Krzysztof Kozlowski wrote:
> On Thu, Jun 25, 2026 at 06:26:43PM +0900, Mikko Perttunen wrote:
> > On Thursday, June 25, 2026 5:36 PM Krzysztof Kozlowski wrote:
> > > On Mon, Jun 22, 2026 at 05:22:51PM +0900, Mikko Perttunen wrote:
> > > > Channels and syncpoints available may be limited when other system
> > > 
> > > What are channels and syncpoints?
> > 
> > Very host1x-specific hardware resources. Somewhat close to GPU channels
> > and semaphores / fences if you're familiar with those.
> > 
> > > 
> > > > components are using them. Add properties nvidia,channels and
> > > > nvidia,syncpoints to limit the range of usable channels and/or
> > > > syncpoints.
> > > 
> > > Why isn't this deducible from the compatible?
> > 
> > When Host1x is partitioned, the hypervisor (or other software entity
> > with access to the non-vm host1x register regions) can configure which
> > channels and syncpoints are available to each partition arbitrarily.
> 
> So you will have different boards for the same SoC with different
> values?
> 

Yes -- even the same board will have different values depending on the
use case of the system. The hypervisor or bootloader has to update the
properties according to the configuration it has programmed in the
hardware.

I will update the commit message with clarification.

> > 
> > How that partitioning was done is not discoverable through hardware
> > directly, so we need to pass that information through device tree.
> > 
> > > 
> > > Also, nvidia,channels is too broad/generic. This is not ADC, right? And
> > > channels is a common term in IIO. And in few other cases.
> > 
> > It's not ADC. Yes, it's a common term in a lot of contexts. I can call
> > it nvidia,host1x-channels if you prefer but that seems a bit redundant
> > given the context.
> 
> host1x is indeed poor, but maybe there is some way to be a bit more
> descriptive? message-channels?

I would prefer to keep these as is -- anyone working with host1x will
know what 'channels' and 'syncpoints' mean, and changing the name could
cause confusion since the name would not match other code or
documentation discussing these.

I can update the binding documentation with some more explanation about
what these properties mean.

Thank you
Mikko

> 
> Best regards,
> Krzysztof
>