> -----Original Message----- > From: Will Deacon [mailto:will.deacon@xxxxxxx] > Sent: 04 April 2019 16:47 > To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx> > Cc: lorenzo.pieralisi@xxxxxxx; robin.murphy@xxxxxxx; > andrew.murray@xxxxxxx; jean-philippe.brucker@xxxxxxx; > mark.rutland@xxxxxxx; Guohanjun (Hanjun Guo) <guohanjun@xxxxxxxxxx>; > John Garry <john.garry@xxxxxxxxxx>; pabba@xxxxxxxxxxxxxx; > vkilari@xxxxxxxxxxxxxx; rruigrok@xxxxxxxxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; Linuxarm > <linuxarm@xxxxxxxxxx>; neil.m.leeder@xxxxxxxxx > Subject: Re: [PATCH v7 4/4] perf/smmuv3: Enable HiSilicon Erratum 162001800 > quirk > > On Tue, Mar 26, 2019 at 03:17:53PM +0000, Shameer Kolothum wrote: > > HiSilicon erratum 162001800 describes the limitation of > > SMMUv3 PMCG implementation on HiSilicon Hip08 platforms. > > > > On these platforms, the PMCG event counter registers > > (SMMU_PMCG_EVCNTRn) are read only and as a result it > > is not possible to set the initial counter period value > > on event monitor start. > > > > To work around this, the current value of the counter > > is read and used for delta calculations. OEM information > > from ACPI header is used to identify the affected hardware > > platforms. > > > > Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx> > > Reviewed-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx> > > Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx> > > --- > > drivers/acpi/arm64/iort.c | 16 ++++++++++++++- > > drivers/perf/arm_smmuv3_pmu.c | 48 > ++++++++++++++++++++++++++++++++++++------- > > include/linux/acpi_iort.h | 1 + > > 3 files changed, 57 insertions(+), 8 deletions(-) > > > > diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c > > index e2c9b26..4dc68de 100644 > > --- a/drivers/acpi/arm64/iort.c > > +++ b/drivers/acpi/arm64/iort.c > > @@ -1366,9 +1366,23 @@ static void __init > arm_smmu_v3_pmcg_init_resources(struct resource *res, > > ACPI_EDGE_SENSITIVE, &res[2]); > > } > > > > +static struct acpi_platform_list pmcg_plat_info[] __initdata = { > > + /* HiSilicon Hip08 Platform */ > > + {"HISI ", "HIP08 ", 0, ACPI_SIG_IORT, greater_than_or_equal, 0, > > Passing integer constant 0 for the reason feels wrong to me. I'm going to > change it to "Erratum #162001800" and also add an entry to > silicon-errata.txt. > > Please shout if that's not ok. Thanks Will for taking a look at this series. The proposed changes are fine to me. Shameer
