RE: [PATCH v2 2/4] xlnx_dp: Introduce a vblank signal

[Frederic Konrad]

> -----Original Message-----
> From: Peter Maydell <peter.maydell@linaro.org>
> Sent: 23 May 2022 14:52
> To: Frederic Konrad <fkonrad@amd.com>
> Cc: qemu-devel@nongnu.org; qemu-arm@nongnu.org;
> edgar.iglesias@gmail.com; alistair@alistair23.me; Sai Pavan Boddu
> <saipava@xilinx.com>; Edgar Iglesias <edgari@xilinx.com>; Sai Pavan Boddu
> <saipava@xilinx.com>; Edgar Iglesias <edgari@xilinx.com>
> Subject: Re: [PATCH v2 2/4] xlnx_dp: Introduce a vblank signal
> 
> [CAUTION: External Email]
> 
> On Thu, 19 May 2022 at 16:39, Frederic Konrad <fkonrad@amd.com> wrote:
> >
> > From: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>
> >
> > Add a periodic timer which raises vblank at a frequency of 30Hz.
> >
> > Signed-off-by: Sai Pavan Boddu <saipava@xilinx.com>
> > Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
> > Changes by fkonrad:
> >   - Switched to transaction-based ptimer API.
> >   - Added the DP_INT_VBLNK_START macro.
> > Signed-off-by: Frederic Konrad <fkonrad@amd.com>
> > ---
> 
> 
> > @@ -107,6 +108,8 @@ struct XlnxDPState {
> >       */
> >      DPCDState *dpcd;
> >      I2CDDCState *edid;
> > +
> > +    ptimer_state *vblank;
> >  };
> 
> The ptimer has internal state which needs to be considered in
> migration. This means you need to either include it in the device
> vmstate struct (there is a VMSTATE_PTIMER macro for this), or
> else set it up again in a post-load hook. Otherwise if you do
> a migration or state save/load when the timer is running then
> on resume the timer won't be running when it should.

Ah yes indeed, I forgot about that.  Since cross version migration is not 
relevant
here, the VMSTATE_PTIMER would be acceptable right?

> 
> Apologies for not noticing this in my first review.

No worries, thanks for the review :).

Fred

> 
> -- PMM