Re: [PATCH v2 1/7] arm64: capabilities: Merge entries for ARM64_WORKAROUND_CLEAN_CACHE

[Suzuki K Poulose]

On 05/12/2018 15:02, Will Deacon wrote:
> On Fri, Nov 30, 2018 at 05:18:00PM +0000, Suzuki K Poulose wrote:
> > We have two entries for ARM64_WORKAROUND_CLEAN_CACHE capability :
> >
> > 1) ARM Errata 826319, 827319, 824069, 819472 on A53 r0p[012]
> > 2) ARM Errata 819472 on A53 r0p[01]
> >
> > Both have the same work around. Merge these entries to avoid
> > duplicate entries for a single capability. Add a new Kconfig
> > entry to control the "capability" entry to make it easier
> > to handle combinations of the CONFIGs.
> >
> > Cc: Will Deacon <will.deacon@xxxxxxx>
> > Cc: Andre Przywara <andre.przywara@xxxxxxx>
> > Cc: Mark Rutland <mark.rutland@xxxxxxx>
> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> > ---
> >   arch/arm64/Kconfig               |  7 +++++++
> >   arch/arm64/include/asm/cputype.h |  1 +
> >   arch/arm64/kernel/cpu_errata.c   | 28 ++++++++++++++++------------
> >   3 files changed, 24 insertions(+), 12 deletions(-)
> >
> > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> > index 787d785..ad69e15 100644
> > --- a/arch/arm64/Kconfig
> > +++ b/arch/arm64/Kconfig
> > @@ -313,9 +313,13 @@ menu "Kernel Features"
> >   
> >   menu "ARM errata workarounds via the alternatives framework"
> >   
> > +config ARM64_WORKAROUND_CLEAN_CACHE
> > +	def_bool n
> > +
> >   config ARM64_ERRATUM_826319
> >   	bool "Cortex-A53: 826319: System might deadlock if a write cannot complete until read data is accepted"
> >   	default y
> > +	select ARM64_WORKAROUND_CLEAN_CACHE
> >   	help
> >   	  This option adds an alternative code sequence to work around ARM
> >   	  erratum 826319 on Cortex-A53 parts up to r0p2 with an AMBA 4 ACE or
> > @@ -337,6 +341,7 @@ config ARM64_ERRATUM_826319
> >   config ARM64_ERRATUM_827319
> >   	bool "Cortex-A53: 827319: Data cache clean instructions might cause overlapping transactions to the interconnect"
> >   	default y
> > +	select ARM64_WORKAROUND_CLEAN_CACHE
> >   	help
> >   	  This option adds an alternative code sequence to work around ARM
> >   	  erratum 827319 on Cortex-A53 parts up to r0p2 with an AMBA 5 CHI
> > @@ -358,6 +363,7 @@ config ARM64_ERRATUM_827319
> >   config ARM64_ERRATUM_824069
> >   	bool "Cortex-A53: 824069: Cache line might not be marked as clean after a CleanShared snoop"
> >   	default y
> > +	select ARM64_WORKAROUND_CLEAN_CACHE
> >   	help
> >   	  This option adds an alternative code sequence to work around ARM
> >   	  erratum 824069 on Cortex-A53 parts up to r0p2 when it is connected
> > @@ -380,6 +386,7 @@ config ARM64_ERRATUM_824069
> >   config ARM64_ERRATUM_819472
> >   	bool "Cortex-A53: 819472: Store exclusive instructions might cause data corruption"
> >   	default y
> > +	select ARM64_WORKAROUND_CLEAN_CACHE
> >   	help
> >   	  This option adds an alternative code sequence to work around ARM
> >   	  erratum 819472 on Cortex-A53 parts up to r0p1 with an L2 cache
> > diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h
> > index 12f93e4d..2e26375 100644
> > --- a/arch/arm64/include/asm/cputype.h
> > +++ b/arch/arm64/include/asm/cputype.h
> > @@ -151,6 +151,7 @@ struct midr_range {
> >   		.rv_max = MIDR_CPU_VAR_REV(v_max, r_max),	\
> >   	}
> >   
> > +#define MIDR_REV_RANGE(m, v, r_min, r_max) MIDR_RANGE(m, v, r_min, v, r_max)
>
> What's the point of this macro?

That can be used to specify a set of MIDRs which has the same "variant" but a
range of "revisions". This is used for the A53 errata and also for the Cavium
errata in the following patch.

Suzuki