Removed most CC: SMTP server protested.
On 01.09.2021 22:19, Douglas Anderson wrote:
The goal of this patch series is to move away from hardcoding exact eDP panels in device tree files. As discussed in the various patches in this series (I'm not repeating everything here), most eDP panels are 99% probable and we can get that last 1% by allowing two "power up" delays to be specified in the device tree file and then using the panel ID (found in the EDID) to look up additional power sequencing delays for the panel.
This patch series is the logical contiunation of a previous patch series where I proposed solving this problem by adding a board-specific compatible string [1]. In the discussion that followed it sounded like people were open to something like the solution proposed in this new series.
In version 2 I got rid of the idea that we could have a "fallback" compatible string that we'd use if we didn't recognize the ID in the EDID. This simplifies the bindings a lot and the implementation somewhat. As a result of not having a "fallback", though, I'm not confident in transitioning any existing boards over to this since we'll have to fallback to very conservative timings if we don't recognize the ID from the EDID and I can't guarantee that I've seen every panel that might have shipped on an existing product. The plan is to use "edp-panel" only on new boards or new revisions of old boards where we can guarantee that every EDID that ships out of the factory has an ID in the table.
Version 3 of this series now splits out all eDP panels to their own driver and adds the generic eDP panel support to this new driver. I believe this is what Sam was looking for [2].
[1] https://lore.kernel.org/r/YFKQaXOmOwYyeqvM@google.com/ [2] https://lore.kernel.org/r/YRTsFNTn%2FT8fLxyB@ravnborg.org/
I like the idea - if something can be configured dynamically lets do it. But I have few questions: 1. Have you read different real panels id's? In many cases (MIPI DSI, LVDS with EDID) manufacturers often forgot to set proper id fields. I do not know how EDID's ids are reliable in case of edp panels. 2. You are working with edp panels - beside EDID they have DPCD which contains things like IEEE_OUI and "Device Identification String", I guess they could be also used for detecting panels, have you considered it? I think DPCD Id should be assigned to EDP-Sink interface, and EDID Id to the actual panel behind it. With this assumption one could consider which timings should be property of which entity.
Regards Andrzej