Hi Aisheng, On 19-02-20 09:49, Aisheng Dong wrote: > > From: Marco Felsch [mailto:m.felsch@xxxxxxxxxxxxxx] > > Sent: Wednesday, February 20, 2019 4:17 PM > > On 19-02-20 03:38, Aisheng Dong wrote: > > > [...] > > > > > > > > I don't like droping some ID's (e.g. IMX_SC_R_DC_0_CAPTURE0) by > > > > > mark them as unused or even worse give them a other meaning. IMHO > > > > > the scu-api should be stable since day 1 and the ID's should only be > > extended. > > > > > Marking ID's as deprecated is much better than moving them around. > > > > > > > > I agree the SCU APIs should be stable since day 1 and the ID should > > > > ONLY be extended, but that is the best cases, the reality is, there > > > > are different SoCs/Revision, some revisions may remove the resources > > > > ID defined in pre-coded SCU firmware, like the > > > > IMX_SC_R_DC_0_CAPTURE0 etc., so SCU APIs removes them after real > > > > silicon arrived, now latest SCU firmware marks them as UNUSED, they > > > > could be replaced by some other new resources in later new SoC, I am > > > > NOT sure, but if it happens, this resource ID table should be > > > > updated anyway, leaving the out-of-date resource ID table there will have > > issues, since it is NOT sync with SCU firmware. > > > > > > > > So how to resolve such issue? We hope the SCU firmware should be > > > > stable since day 1, but the truth is NOT, could be still some > > > > updates but NOT very often. And I believe the updates will NOT break old > > kernel version. > > > > Hi Anson, > > > > Please don't mix the dt-bindings and the kernel related stuff. > > Unfortunately the bindings are within the kernel repo which in fact is great for > > us kernel developer but the bindings are also used in other projects such as > > barebox or other kernels (don't know the BSD guys). So you can't ensure that > > your change will break something. Please keep that in mind. > > > > IMHO solving that issue should be done by the scu firmware. I tought the scu is > > a cortex-m4 with a bunch of embedded flash and ram (I don't know that much > > about the scu since it is closed/black-boxed). Why do you don't use a > > translation table within the scu? As I said earlier I don't like the redefinition of > > ID's since they are now part of the dt-bindings. > > The bindings can store up to 32bit values which is a large number ;) IMHO > > wasting some ID's in favour of stability is a better solution. > > > > As far as I know, those remove resource IDs are pre-defined and has never been used > and won't be used anymore by SC firmware. (Anson can double check it) > So I think it's safe to remove them or mark them as deprecated. I think marking them as deprecated by a commentar is better than redefining bits to be unused. As I said the bindings not only linux related they are used in other projects too. > > Personally I may prefer to remove them as they never worked to avoid confusing, > especially at this early stage for mx8. So why they are there if they never worked? Wouldn't it a better approach to start with a basic and working ID file and extend this rather than adding id's because maybe the will work.. Sorry but this seems wrong to me too. I know the approach from driver development, adding a driver specific *_reg.h file and later figuring out that those bits won't work as aspected. As I said this will be driver and only linux related so we can change them as many times as we want. But in your case we are talking about dt-bindings and this approach won't work. Regards, Marco > > Regards > Dong Aisheng > -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
