Re: [Qemu-devel] [PATCH v4] target-arm: Make the counter tick relative to cntfrq

["Andrew Jeffery" <andrew@aj.id.au>]

On Thu, 12 Sep 2019, at 15:52, Cédric Le Goater wrote:
> On 12/09/2019 05:25, Andrew Jeffery wrote:
> > Allow machines to configure CNTFRQ via a property if the ARM core
> > supports the generic timer. This is necessary on e.g. the ASPEED AST2600
> > SoC where the generic timer clock is run at 800MHz or above. The default
> > value for CNTFRQ remains at 62.50MHz (based on GTIMER_SCALE).
> > 
> > CNTFRQ is a read-as-written co-processor register; the property sets the
> > register's initial value which is used during realize() to configure the
> > QEMUTimers that back the generic timers. Beyond that the firmware can to
> > do whatever it sees fit with the CNTFRQ register though changes to the
> > value will not be reflected in the timers' rate.
> > 
> > I've tested this using an out-of-tree AST2600 SoC model (Cortex-A7) with
> > the SDK u-boot that sets CNTFRQ as appropriate, and by starting/running
> > machines with assorted ARM CPUs (palmetto-bmc with the ARM926EJ-S,
> > romulus-bmc with the ARM1176 and raspi2 with the Cortex-A53).
> > 
> > Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
> > ---
> > v4: Fix configuration for cores without a generic timer
> > 
> > v3: https://patchwork.ozlabs.org/patch/1160634/
> > Peter - I think this addresses most of your feedback. I still reach into
> > the QEMUTimer to fetch out scale when adjusting the nexttick
> > calculation, but we no longer need to update the scale member and force
> > a recalculation of the period.
> > 
> > v2: https://patchwork.ozlabs.org/patch/1144389/
> > ---
> >  roms/SLOF           |  2 +-
> >  roms/skiboot        |  2 +-
> >  target/arm/cpu.c    | 43 +++++++++++++++++++++++++++++++++++--------
> >  target/arm/cpu.h    |  3 +++
> >  target/arm/helper.c | 30 ++++++++++++++++++++++++++----
> >  5 files changed, 66 insertions(+), 14 deletions(-)
> > 
> > diff --git a/roms/SLOF b/roms/SLOF
> > index 7bfe584e3219..ea221600a116 160000
> > --- a/roms/SLOF
> > +++ b/roms/SLOF
> > @@ -1 +1 @@
> > -Subproject commit 7bfe584e321946771692711ff83ad2b5850daca7
> > +Subproject commit ea221600a116883137ef90b2b7ab7d2472bc4f10
> > diff --git a/roms/skiboot b/roms/skiboot
> > index 261ca8e779e5..3a6fdede6ce1 160000
> > --- a/roms/skiboot
> > +++ b/roms/skiboot
> > @@ -1 +1 @@
> > -Subproject commit 261ca8e779e5138869a45f174caa49be6a274501
> > +Subproject commit 3a6fdede6ce117facec0108afe716cf5d0472c3f
> 
> 
> The changes above seem not related.

How did they get in there? :eyeroll:

Thanks. v5 I guess.

Andrew