On Fri, Mar 18, 2022 at 02:55:08AM +0530, Kuldeep Singh wrote: > On Thu, Mar 17, 2022 at 08:25:12PM +0000, Robin Murphy wrote: > > On 2022-03-17 19:15, Kuldeep Singh wrote: > > > Renesas RZ/N1D platform uses compatible "arm,cortex-a7-timer" in > > > conjugation with "arm,armv7-timer". Since, initial entry is not > > > documented, it start raising dtbs_check warnings. > > > > > > ['arm,cortex-a7-timer', 'arm,armv7-timer'] is too long > > > 'arm,cortex-a7-timer' is not one of ['arm,armv7-timer', 'arm,armv8-timer'] > > > 'arm,cortex-a7-timer' is not one of ['arm,cortex-a15-timer'] > > > > > > Document this compatible to address it. The motivation to add this > > > change is taken from an already existing entry "arm,cortex-a15-timer". > > > Please note, this will not hurt any arch timer users. > > > > Eh, if it's never been documented or supported, I say just get rid of it. > > The arch timer interface is by definition part of a CPU, and we can tell > > what the CPU is by reading its ID registers. Indeed that's how the driver > > handles the non-zero number of CPU-specific errata that already exist - we > > don't need compatibles for that. > > > > In some ways it might have been nice to have *SoC-specific* compatibles > > given the difficulty some integrators seem to have had in wiring up a stable > > count *to* the interface, but it's not like they could be magically added to > > already-deployed DTs after a bug is discovered, and nor could we have > > mandated them from day 1 just in case and subsequently maintained a binding > > that is just an ever-growing list of every SoC. Oh well. > > Robin, A similar discussion was already done on v1 thread. Please see > below for details: > https://lore.kernel.org/linux-devicetree/20220317065925.GA9158@9a2d8922b8f1/ > https://lore.kernel.org/linux-devicetree/726bde76-d792-febf-d364-6eedeb748c3b@xxxxxxxxxxxxx/ > > And final outcome of discussion turns out to add this compatible string. I agree with Robin on dropping. More specific here is not useful. If we're going to add some cores, then we should add every core implementation. If one has a big.LITTLE system with A15/A7 what would be the right compatible value? > > I see people with different set of perspective in regard to whether keep > compatible string or not. We should have some sort of evidences to > support claims so that next time when similar situation arises, we'll be > aware beforehand how to proceed. Every situation tends to be different. Rob
