On Thu, Nov 12, 2015 at 6:11 PM, Stephen Boyd <sboyd@xxxxxxxxxxxxxx> wrote: > On 11/12, Rob Herring wrote: >> On Thu, Nov 12, 2015 at 1:44 PM, Stephen Boyd <sboyd@xxxxxxxxxxxxxx> wrote: >> > On 11/12, Rob Herring wrote: >> >> On Mon, Oct 26, 2015 at 02:25:10PM -0700, Stephen Boyd wrote: >> >> >> > +Some qcom based bootloaders identify the dtb blob based on a set of >> >> > +device properties like SoC, platform, PMIC, and revisions of those components. >> >> > +To support this scheme, we encode this information into the board compatible >> >> > +string. >> >> >> >> Why does all this need to be a single property? >> > >> > Because the different vendor properties were rejected by arm-soc >> > maintainers and the board compatible string was suggested as the >> > place to put such information. >> >> I'm surprised an 80+ character compatible stream is okay. The parts >> giving me heartburn here are not mentioned in the previous discussion >> nor the QCDT format. >> >> As presented previously I agree with the push back. However, we could >> do standard properties for SOC and board versions rather than >> something vendor specific. Then the existing kernel support for >> versions could use it. We could also just make this compatible string >> formatting standard for more than just QC boards. > > Some standard properties for these things sounds good to me. > What's the existing kernel support for versions though? Is that > just compatible string matching, or something else? The soc_device stuff (and arm32 cpuinfo has a h/w version). Today I think users are pulling version info from h/w registers, but if you don't have h/w registers, then getting it from DT would make sense. >> For mb, can't the tool just parse the memory node to get ram size >> rather than parsing the compatible. > > Sure. Right now the bootloader injects the memory information > during boot. I think it should work if we already have the memory > information there. I don't have any usage of mb at the moment > though, so if you want we can drop this field until a time that > we need it. If the bootloader injects it, then how do you know what to put into the compatible string? >> >> > +The 'panel' element must be one of the following strings: >> >> > + >> >> > + 720p >> >> > + fWVGA >> >> > + hd >> >> > + qHD >> >> >> >> How is this used? >> > >> > I believe this was added so that we could have different dtbs for >> > devices that have different panels on them. I'm not sure this is >> > still used though. It could be legacy. >> >> Dealing with multiple panels is fairly common. I think you could use >> an alias to the panel node and match using its compatible or >> resolution. > > So dtbtool will need to resolve the alias and then figure out > which type of panel it is from compatible? Ok. I'd rather not > write that code unless it's needed, so I hope this field is not > used either. Certainly better to figure out if it is needed first. >> >> > +The 'boot' element must be one of the following strings: >> >> > + >> >> > + emmc_sdc1 >> >> > + ufs >> >> > + >> >> Again, perhaps an alias would work here. >> >> >> > +The 'pmic' element must be one of the following strings: >> >> > + >> >> > + pm8841 >> >> > + pm8019 >> >> > + pm8110 >> >> > + pma8084 >> >> > + pmi8962 >> >> > + pmd9635 >> >> > + pm8994 >> >> > + pmi8994 >> >> > + pm8916 >> >> > + pm8004 >> >> > + pm8909 >> >> > + >> >> > +The 'pmic' element is specified in order of ascending USID. The PMIC in USID0 >> >> > +goes first, and then USID2, USID4, and finally USID6. Up to four PMICs may be >> >> > +specified and no holes in the USID number space are allowed. >> >> >> >> What is USID? >> > >> > USID is Unique Slave IDentifier. It's an SPMI concept. >> >> Okay, then please say "SPMI USID" or something. > > Ok. > > In attempts to shorten the compatible string, we could use > aliases for the USIDs too. Then it should be possible to pull out > the information from the compatible fields of the PMIC nodes to > construct the PMIC part of the string. I'd like to avoid having > to go down the path of / -> soc -> spmi controller -> usidx,y,z > and just go straight to the usid node from a phandle. Yes. I was willing to draw the line after the PMIC, but seems Olof is less so. > With that in mind, right now I'm using fdtget from python to grab > the compatible string and parse it with a regex. If things need > to become more complicated to start following phandles, etc. are > there some python bindings to libfdt somewhere? Not that I'm aware of. C is the only language you need. ;) Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
