Re: [PATCH 00/14] Add initial support for the Rockchip RK3588 HDMI TX Controller

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Hi,

On 03/06/2024 15:03, Heiko Stuebner wrote:
Am Montag, 3. Juni 2024, 14:14:17 CEST schrieb Andy Yan:
Hi Neil:

On 6/3/24 16:55, Neil Armstrong wrote:
Hi Christian,

On 01/06/2024 15:12, Cristian Ciocaltea wrote:
The RK3588 SoC family integrates a Quad-Pixel (QP) variant of the
Synopsys DesignWare HDMI TX controller used in the previous SoCs.

It is HDMI 2.1 compliant and supports the following features, among
others:

.

..

* SCDC I2C DDC access
* TMDS Scrambler enabling 2160p@60Hz with RGB/YCbCr4:4:4
* YCbCr4:2:0 enabling 2160p@60Hz at lower HDMI link speeds
* Multi-stream audio
* Enhanced Audio Return Channel (EARC)
-> Those features were already supported by the HDMI 2.0a compliant HW, just
list the _new_ features for HDMI 2.1

I did a quick review of your patchset and I don't understand why you need
to add a separate dw-hdmi-qp.c since you only need simple variants of the I2C
bus, infoframe and bridge setup.

Can you elaborate further ? isn't this Quad-Pixel (QP) TX controller version
detectable at runtime ?

I would prefer to keep a single dw-hdmi driver if possible.



The QP HDMI controller is a completely different variant with totally different
registers layout, see PATCH 13/14.
I think make it a separate driver will be easier for development and maintenance.

I'm with Andy here. Trying to navigate a driver for two IP blocks really
sounds taxing especially when both are so different.

I agree, I just wanted more details than "variant of the
Synopsys DesignWare HDMI TX controller", if the register mapping is 100%
different, and does not match at all with the old IP, then it's indeed time
to make a brand new driver, but instead of doing a mix up, it's time to extract
the dw-hdmi code that could be common helpers into a dw-hdmi-common module
and use them.

As I see, no "driver" code can be shared, only DRM plumbings, so perhaps those
plumbing code should go into the DRM core ?

In any case, please add more details on the cover letter, including the detailed
HW differrence and the design you chose so support this new IP.

Neil


Synopsis also created a new dsi controller for the DSI2 standard, with
a vastly different registers layout.

I guess at some point there is time to say this really is a new IP ;-) .


Though while on that thought, I don't fully understand why both a compiled
under the dw_hdmi kconfig symbol. People going for a minimal kernel might
want one or the other, but not both for their specific board.


Heiko







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