On Sun, Jul 15, 2018 at 03:35:45PM -0500, J. Agustín Vega-Frías wrote: > On Fri, Jul 13, 2018 at 10:33 AM, Will Deacon <will.deacon@xxxxxxx> wrote: > > I'm mostly ok with this approach, but I have a concern with the way in which > > the sysfs interface for carving up the config fields is implemented. If this > > is intended to be a strict extension to the armv8 pmu architecture, then I > > don't think you should be overriding the attr_groups entirely. Rather, you > > should be taking the attr_groups from pmuv3 and then extending them in a way > > which avoids overlapping field allocations by construction. > > > > As it stands, you already have an overlap between the pcc bit and the > > chained counter bit which Suzuki has implemented and it will be very easy to > > introduce API breakage if we don't enforce this as part of the design. > > > > Will > > FYI, I left Qualcomm on July 6, one of my former colleagues will submit > new iterations of this series. I will continue to comment on this and future > patchsets as a courtesy to my former colleagues and the community. > > Thanks for pointing out the sysfs issue. My suggestion on how to address it is: > > 1. Reserve config and config1 for architectural format attributes and > config2 for extension format attributes. > 2. Add a struct attribute ** parameter to the extension init function so > extensions can return the new attributes. > 3. The extension framework code in arm_pmu_acpi.c can then allocate a new > attribute array to contain the base and extension attributes and ensure > all the new attributes are on config2. > > Though a more elaborate approach can be implemented to find conflicts in > bit usage within config fields, it would require much more code for a > relatively simple problem. Thoughts? As long as you're happy to live inside config2, that sounds sensible to me. Will -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
