Hi, On Wed, Dec 13, 2023 at 7:34 AM Maxime Ripard <mripard@xxxxxxxxxx> wrote: > > > > > Repeating my comments from v1 here too, since I expect this patch to > > > > sit on the lists for a little while: > > > > > > > > > > > > This is OK w/ me, but it will need time on the mailing lists before > > > > landing in case anyone else has opinions. > > > > > > Generally speaking, I'm not really a fan of big patches that dump > > > whatever ChromeOS is doing ... > > > > > > > Specifical thoughts: > > > > > > > > * I at least feel fairly confident that this is OK since these panels > > > > essentially booted without _any_ delays back on the old downstream > > > > v4.19 kernel. Presumably the panels just had fairly robust timing > > > > controllers and so worked OK, but it's better to get the timing more > > > > correct. > > > > > > ... especially since you have to rely on the recollection of engineers > > > involved at the time and you have no real way to test and make things > > > clearer anymore, and we have to take patches in that are handwavy "trust > > > us, it's doing the right thing". > > > > > > I'd really prefer to have these patches sent as they are found out. > > > > It's probably not clear enough from the commit message, but this isn't > > just a dump from downstream 4.19. What happened was: > > > > 1. Downstream chromeos-4.19 used the "little white lie" approach. They > > all claimed a specific panel's compatible string even though there > > were a whole pile of panels out there actually being used. Personally, > > this was not something I was ever a fan of (and I wasn't personally > > involved in this project), but it was the "state of the art" before > > the generic panel-edp. Getting out of the "little white lie" situation > > was why I spent so much time on the generic edp-panel solution > > upstream. > > > > 2. These devices have now been uprevved to a newer kernel and I > > believe that there were issues seen that necessitated a move to the > > proper generic panel-edp code. > > > > 3. We are now getting field reports from our warning collector about a > > whole pile of panels that are falling back to the "conservative" > > timings, which means that they turn on/off much more slowly than they > > should. > > > > Pin-yen made an attempt to search for panels data sheets that matched > > up with the IDs that came in from the field reports but there were > > some panels that he just couldn't find. > > > > So basically we're stuck. Options: > > > > 1. Leave customers who have these panels stuck with the hardware > > behaving worse than it used to. This is not acceptable to me. > > > > 2. Land Pin-yen's patch as a downstream-only patch in ChromeOS. This > > would solve the problem, but it would make me sad. If anyone ever > > wants to take these old laptops and run some other Linux distribution > > on them (and there are several that target old Chromebooks) then > > they'd be again stuck with old timings. > > > > 3. Land a patch like this one that at least gets us into not such a bad shape. > > > > While I don't love this patch (and that's why I made it clear that it > > needs to spend time on the list), it seems better than the > > alternatives. Do you have a proposal for something else? If not, can > > you confirm you're OK with #3 given this explanation? ...and perhaps > > more details in the commit message? > > I don't have a specific comment, it was more of a comment about the > process itself, if you write down what's above in the commit message ... Pin-yen: can you take a whack at summarizing some of the above in the commit message and sending out a v3?
