Re: [PATCH v4 7/7] drm/tegra: Add support for 8-bit CPU interface

[Mikko Perttunen]

On Friday, October 23, 2026 11:14 PM Svyatoslav Ryhel wrote:
> пт, 23 жовт. 2026 р. о 11:26 Svyatoslav Ryhel <clamor95@xxxxxxxxx> пише:
> >
> > пт, 23 жовт. 2026 р. о 10:53 Mikko Perttunen <mperttunen@xxxxxxxxxx> пише:
> > >
> ...
> > > > +MODULE_ALIAS("platform:tegra-dbi");
> > > > +MODULE_AUTHOR("Svyatoslav Ryhel <clamor95@xxxxxxxxx>");
> > > > +MODULE_DESCRIPTION("Nvidia Tegra20/30 MIPI-DBI Type B driver");
> > > > +MODULE_LICENSE("GPL");
> > >
> > > No separate platform driver or device. If a separate struct device is
> > > needed for some technical purpose, we need to create a minimal separate
> > > virtual device, but unless there is a strong reason to have that we
> > > should be fine with just the dc device.
> > >
> > > Thank you
> > > Mikko
> > >
> >
> > ATM, I use bridge framework to describe interface and I am attaching
> > it to RGB since it basically uses RGB to transfer video data. It works
> > pretty nice so far.
> >
> > You propose to replicate how RGB works just for DBI?
> >
> 
> One of the reasons I used separate pdev was to be able get mipi_dbi
> from it using dev_get_drvdata() from patent (dbi bridge in this case).
> DBI framework seems to not have a way to pass it in any other way,
> unless you know smth I don't.

Right, I think using a bridge is fine; passing the mipi_dbi interface is 
properly done in other ways. The direct parent devdata link is a bit of 
a "poor man's bus", and sometimes it breaks down, such as here.

MIPI DBI is comparable to MIPI DSI -- both have a hardware channel that 
sends both pixel data and commands. I think we should follow DSI's 
example and have a DBI bus and devices while keeping it as simple as 
possible.

The DC driver would register a DBI host and the panel would bind as a 
DBI device. The DC driver can then supply the mipi_dbi object in a field 
of the mipi_dbi_device.

This is a bit more complicated than a parent devdata pointer but much 
cleaner, and follows the existing DSI pattern.