On 29/03/17 11:27, Leo Yan wrote:

On Wed, Mar 29, 2017 at 10:07:07AM +0100, Suzuki K Poulose wrote:

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+	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.

My switch...case suggestion makes it easier to do all this checking.


Thanks
Suzuki