On 23/10/2022 08:24, Daniel Golle wrote: > Hi Krzysztof, > > On Sat, Oct 22, 2022 at 12:35:25PM -0400, Krzysztof Kozlowski wrote: >> On 21/10/2022 18:58, Daniel Golle wrote: >>> On Fri, Oct 21, 2022 at 05:23:38PM -0500, Rob Herring wrote: >>>> On Fri, Oct 21, 2022 at 04:25:18PM +0100, Daniel Golle wrote: >>>>> Add new compatible string for MT7986 PWM. >>>>> >>>>> Signed-off-by: Daniel Golle <daniel@xxxxxxxxxxxxxx> >>>>> --- >>>>> Documentation/devicetree/bindings/pwm/pwm-mediatek.txt | 1 + >>>>> 1 file changed, 1 insertion(+) >>>>> >>>>> diff --git a/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt b/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt >>>>> index 554c96b6d0c3e0..6f4e60c9e18b81 100644 >>>>> --- a/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt >>>>> +++ b/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt >>>>> @@ -8,6 +8,7 @@ Required properties: >>>>> - "mediatek,mt7623-pwm": found on mt7623 SoC. >>>>> - "mediatek,mt7628-pwm": found on mt7628 SoC. >>>>> - "mediatek,mt7629-pwm": found on mt7629 SoC. >>>>> + - "mediatek,mt7986-pwm": found on mt7986 SoC. >>>> >>>> This version of the PWM h/w is not compatible with any of the existing >>>> chips? If it is, it should have a fallback compatible. >>> >>> No, it is unique because it comes with just 2 PWM channels. >>> Otherwise the driver behaves just like for MT8183 (4 channels) or >>> MT8365 (3 channels) which also got distinct compatible strings. >> >> Then something would be here compatible. E.g. If you bound MT8183 with >> mt7986-pwm compatible, would you get working device with two channels? > > Yes, but I'd see another 2 channels which do not work, accessing them > may even cause problems (I haven't tried that) as it means accessing > an undocumented memory range of the SoC which we in general we > shouldn't be messing around with. Why on MT8183 there would be undocumented memory? Where is undocumented memory? > > Also note that this case is the same as MT8183 vs. MT8365, they got > distinct compatible strings and also for those two the only difference > is the number of channels. So why they are not made compatible? > >> >> If so, they are compatible. > > By that definition you should remove the additional compatible for > MT8365 or rather, it should have been rejected for the same argument. > > I'm talking about > commit fe00faee8060402a3d85aed95775e16838a6dad2 > commit 394b517585da9fbb2eea2f2103ff47d37321e976 This is a pattern spreading in several Mediatek bindings and we already commented on new patches. I don't know why people working on Mediatek do not mark pieces compatible. Best regards, Krzysztof
