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charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Wed, Jul 10, 2024 at 12:16:58PM -0700, Doug Anderson wrote: > On Wed, Jul 10, 2024 at 12:03 PM Stephan Gerhold > wrote: > > > > > 2. In theory you could make your compatible look like this: > > > > > > compatible = "samsung,atna45af01", "samsung,atna33xc20" > > > > > > ...which would say "I have a 45af01 but if the OS doesn't have > > > anything special to do that it would be fine to use the 33xc20 > > > driver". That would allow device trees to work without the kernel > > > changes and would allow you to land the DT changes in parallel with > > > the driver changes and things would keep working. > > > > > > ...and, in fact, that would mean you _didn't_ need to add the new > > > compatible string to the driver, which is nice. > > > > > > > Yeah, I considered this. I mentioned the reason why I decided against > > this in patch 2: > > > > > While ATNA45AF01 would also work with "samsung,atna33xc20" as a fallback > > > compatible, the original submission of the compatible in commit > > > 4bfe6c8f7c23 ("drm/panel-simple: Add Samsung ATNA33XC20") had the timings > > > and resolution hardcoded. These would not work for ATNA45AF01. > > > > Basically, it works with the current driver. But if you would run the > > kernel at the state of the original submission then it would behave > > incorrectly. This is why I considered the resolution and timings to be > > part of the "samsung,atna33xc20" "ABI". The new panel would not be > > compatible with that. > > Ah, oops. My eyes totally glazed over the description since the patch > was so simple. :-P Sorry about that. > > IMO I'd still prefer using the fallback compatible, but happy to hear > other opinions. In the original commit things were pretty broken still > (sorta like how it's broken for you using "edp-panel") and the > resolution hasn't been hardcoded for a long while... I briefly discussed this with Krzysztof on IRC yesterday and we concluded that a fallback compatible is better. If one considers just the non-discoverable part of the interface for the binding (i.e. the non-standard power sequence), then the two panels are indeed compatible. I will send a v2 with the fallback compatible on Monday. I think this can also simplify backporting the backlight fix as you mentioned, since then no driver change is required to make it work. Thanks, Stephan