Re: [PATCH] Platform/ARM/VExpress: refine the check for DVI support

[Leif Lindholm <leif.lindholm@linaro.org>]

On Mon, Jan 29, 2018 at 04:13:40PM +0000, Ard Biesheuvel wrote:
> On 29 January 2018 at 16:01, Thomas Abraham <thomas.abraham@arm.com> wrote:
> > Hi Leif,
> >
> >> On Mon, Jan 29, 2018 at 8:21 PM, Leif Lindholm <leif.lindholm@linaro.org> wrote:
> >> On Fri, Jan 26, 2018 at 10:34:59PM +0530, Thomas Abraham wrote:
> >> > The base models could have different values for the revision ID field
> >> > in the System ID register. Base models do not have support for DVI and
> >> > so the revision ID field should also be masked out when checking for
> >> > the presence of DVI support.
> >> >
> >> > Contributed-under: TianoCore Contribution Agreement 1.1
> >> > Signed-off-by: Thomas Abraham <thomas.abraham@arm.com>
> >> > ---
> >> >  .../VExpressPkg/Library/PL111LcdArmVExpressLib/PL111LcdArmVExpress.c    |
> >> 2 +-
> >> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >> >
> >> > diff --git
> >> >
> >> a/Platform/ARM/VExpressPkg/Library/PL111LcdArmVExpressLib/PL111LcdArmV
> >> > Express.c
> >> >
> >> b/Platform/ARM/VExpressPkg/Library/PL111LcdArmVExpressLib/PL111LcdArmV
> >> > Express.c
> >> > index 3f3ceb3..89ba130 100644
> >> > ---
> >> >
> >> a/Platform/ARM/VExpressPkg/Library/PL111LcdArmVExpressLib/PL111LcdArmV
> >> > Express.c
> >> > +++
> >> b/Platform/ARM/VExpressPkg/Library/PL111LcdArmVExpressLib/PL111Lcd
> >> > +++ ArmVExpress.c
> >> > @@ -264,7 +264,7 @@ LcdPlatformSetMode (
> >> >    SysId = MmioRead32 (ARM_VE_SYS_ID_REG);
> >> >    if (SysId != ARM_RTSM_SYS_ID) {
> >> >      // Take out the FVP GIC variant to reduce the permutations.
> >> > -    SysId &= ~ARM_FVP_SYS_ID_VARIANT_MASK;
> >> > +    SysId &= ~(ARM_FVP_SYS_ID_VARIANT_MASK |
> >> > + ARM_FVP_SYS_ID_REV_MASK);
> >> >      if (SysId != ARM_FVP_BASE_BOARD_SYS_ID) {
> >> >        // Set the DVI into the new mode
> >> >        Status = ArmPlatformSysConfigSet (SYS_CFG_DVIMODE,
> >> > mResolutions[ModeNumber].Mode);
> >>
> >> I think this change makes sense (and should arguably have been there from the
> >> start). But I also think it highlights that the surrounding comments are incorrect,
> >> and get increasingly confusing with this modification.
> >>
> >> I would suggest that
> >>   // On the FVP models the GIC variant in encoded in bits [15:12].
> >> is replaced by
> >>   // On the FVP models, the build variant is encoded in bits [15:12].
> >>
> >> and that
> >>   // Take out the FVP GIC variant to reduce the permutations.
> >> is replaced by
> >>   // Ignore build variant and revision.
> >>
> >> If you're happy with that, I can fold these changes to the surrounding comments
> >> in and commit.
> >
> > Yes, happy to have these changes folded in. Thank you!.
> >
> 
> Likewise
> 
> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Thanks.

Pushed as cf8aef9c96 with
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
[Reworded adjacent code comments.]
Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
and Ard's ACK.

/
    Leif