From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@arm.linux.org.uk (Russell King - ARM Linux) Date: Thu, 1 Aug 2013 21:15:15 +0100 Subject: [PATCH v2] ARM: Do not run dummy_flush_tlb_a15_erratum() on non-Cortex-A15 In-Reply-To: References: <1374581199-8277-1-git-send-email-festevam@gmail.com> <20130801105824.GE24642@n2100.arm.linux.org.uk> Message-ID: <20130801201515.GE23006@n2100.arm.linux.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Aug 01, 2013 at 03:09:51PM -0500, Rob Herring wrote: > On Thu, Aug 1, 2013 at 5:58 AM, Russell King - ARM Linux > wrote: > > On Wed, Jul 31, 2013 at 11:03:46PM -0500, Rob Herring wrote: > >> I just submitted my patch for 798181 ECO fix handling to the patch > >> system today. Then I noticed this patch in your fixes branch. This is > >> going to cause some churn as my patch needs to move the core version > >> check back to a .c file. > >> > >> I don't know if you are okay with rebasing your fixes branch or not. > >> If my patch is applied first, then this issue can be handled by just > >> replacing dummy_flush_tlb_a15_erratum call in context.c a call to > >> erratum_a15_798181. > > > > Well, firstly, are you sure your patch is correct? > > Yes. > > > You're removing the call to dummy_flush_tlb_a15_erratum() before the > > smp_call_function() - smp_call_function() does _not_ call the function > > for the local CPU. So, what this means is we don't end up doing any > > of the workaround for the local CPU. > > No, dummy_flush_tlb_a15_erratum() is now called from within > erratum_a15_798181 if errata_fix_needed is non-zero. The return value > only means do the IPI or not. > > > Secondly, doesn't the check in your case reduce down to: > > > > unsigned int midr = read_cpuid_id(); > > > > /* Cortex-A15 r0p0..r3p2 affected */ > > if ((midr & 0xff0ffff0) != 0x410fc0f0 || midr > 0x413fc0f2 || > > /* ECO not fully fixed */ > > !(read_cpuid(CPUID_REVIDR) & 0x010)) > > return 0; > > return 1; > > > > because, assuming midr is not satisfied: > > > > revidr errata_fix_needed function return > > 000 2 1 > > 010 1 0 > > 200 2 1 > > 210 0 0 > > > > I think that the above version is still cheap enough to be inline. > > Only because it is incomplete. :) Your timing is very bad. I just sent the entire fixes branch (and some other stuff - which was scheduled for a long time to be sent tonight) off to Linus having waited all day. It was either that or sit on the fixes branch even longer.