On Wed, Mar 29, 2017 at 11:31:03AM +0100, Suzuki K Poulose wrote: > On 29/03/17 11:27, Leo Yan wrote: > >On Wed, Mar 29, 2017 at 10:07:07AM +0100, Suzuki K Poulose wrote: > > > >[...] > > > >>>>>+ if (mode == EDDEVID_IMPL_NONE) { > >>>>>+ drvdata->edpcsr_present = false; > >>>>>+ drvdata->edcidsr_present = false; > >>>>>+ drvdata->edvidsr_present = false; > >>>>>+ } else if (mode == EDDEVID_IMPL_EDPCSR) { > >>>>>+ drvdata->edpcsr_present = true; > >>>>>+ drvdata->edcidsr_present = false; > >>>>>+ drvdata->edvidsr_present = false; > >>>>>+ } else if (mode == EDDEVID_IMPL_EDPCSR_EDCIDSR) { > >>>>>+ if (!IS_ENABLED(CONFIG_64BIT) && > >>>>>+ (pcsr_offset == EDDEVID1_PCSR_NO_OFFSET_DIS_AARCH32)) > >>>>>+ drvdata->edpcsr_present = false; > >>>>>+ else > >>>>>+ drvdata->edpcsr_present = true; > >>>> > >>>>Sorry, I forgot why we do this check only in this mode. Shouldn't this be > >>>>common to all modes (of course which implies PCSR is present) ? > >>> > >>>No. PCSROffset is defined differently in ARMv7 and ARMv8; So finally we > >>>simplize PCSROffset value : > >>>0000 - Sample offset applies based on the instruction state (indicated by PCSR[0]) > >>>0001 - No offset applies. > >>>0010 - No offset applies, but do not use in AArch32 mode! > >>> > >>>So we need handle the corner case is when CPU runs AArch32 mode and > >>>PCSRoffset = 'b0010. Other cases the pcsr should be present. > >> > >>I understand that reasoning. But my question is, why do we check for PCSROffset > >>only when mode == EDDEVID_IMPL_EDPCSR_EDCIDSR and not for say mode == EDDEVID_IMPL_EDPCSR or > >>any other mode where PCSR is present. > > > >Sorry I misunderstood your question. > > > >I made mistake when I analyzed the possbile combination for mode and > >PCSROffset so I thought it's the only case should handle: > >{ EDDEVID_IMPL_EDPCSR_EDCIDSR, EDDEVID1_PCSR_NO_OFFSET_DIS_AARCH32 } > > > >Below three combinations are possible to exist; so you are right, I > >should move this out for the checking: > >{ EDDEVID_IMPL_NONE, EDDEVID1_PCSR_NO_OFFSET_DIS_AARCH32 } > > That need not be covered, as IMPL_NONE says PCSR is not implemented hence you > don't worry about anything as the functionality is missing. This should rather be: > EDDEVID_IMPL_EDPCSR, where only PCSR is implemented. I think below combination doesn't really exist: { EDDEVID_IMPL_EDPCSR, EDDEVID1_PCSR_NO_OFFSET_DIS_AARCH32 }; EDDEVID_IMPL_EDPCSR is only defined in ARMv7 ARM, and EDDEVID1_PCSR_NO_OFFSET_DIS_AARCH32 is only defined in ARMv8 ARM. > My switch...case suggestion makes it easier to do all this checking. Agree. Will do this. Thanks, Leo Yan -- 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