Re: [Qemu-devel] [PATCH v3 8/9] sm501: Perform a full update after palette change

[David Gibson]

On Thu, Jun 14, 2018 at 10:00:50AM +0200, BALATON Zoltan wrote:
> On Thu, 14 Jun 2018, David Gibson wrote:
> > On Thu, Jun 14, 2018 at 02:17:00AM +0200, BALATON Zoltan wrote:
> > > From: Sebastian Bauer <address@hidden>
> > > 
> > > Signed-off-by: Sebastian Bauer <address@hidden>
> > > Signed-off-by: BALATON Zoltan <address@hidden>
> > 
> > Commit message.  Why is this necessary?
> 
> Maybe because changing palette does not change display unless an update is
> done and dirty tracking which is used in update_display does not detect
> changes in device registers where palette is stored.
> 
> I'm not sure this is needed in all modes but I guess palette is not used in
> modes that are not indexed so unecessary updates should not happen evem in
> those cases because if palette is not used anyway, guest is unlikely to
> change it unless doing something really strange but we haven't seen any
> guests yet that would do that. Therefore this simple way of handling this
> should be OK.

Sure, so, put that into a commit message in the next spin.

> 
> Regards,
> BALATON Zoltan
> 
> > > ---
> > >  hw/display/sm501.c | 8 ++++++++
> > >  1 file changed, 8 insertions(+)
> > > 
> > > diff --git a/hw/display/sm501.c b/hw/display/sm501.c
> > > index 0625cf5..a2ee6e3 100644
> > > --- a/hw/display/sm501.c
> > > +++ b/hw/display/sm501.c
> > > @@ -479,6 +479,7 @@ typedef struct SM501State {
> > >      MemoryRegion twoD_engine_region;
> > >      uint32_t last_width;
> > >      uint32_t last_height;
> > > +    uint32_t do_full_update; /* perform a full update next time */
> > >      I2CBus *i2c_bus;
> > > 
> > >      /* mmio registers */
> > > @@ -1032,6 +1033,7 @@ static void sm501_palette_write(void *opaque, 
> > > hwaddr addr,
> > > 
> > >      assert(range_covers_byte(0, 0x400 * 3, addr));
> > >      *(uint32_t *)&s->dc_palette[addr] = value;
> > > +    s->do_full_update = 1;
> > >  }
> > > 
> > >  static uint64_t sm501_disp_ctrl_read(void *opaque, hwaddr addr,
> > > @@ -1620,6 +1622,12 @@ static void sm501_update_display(void *opaque)
> > >          full_update = 1;
> > >      }
> > > 
> > > +    /* someone else requested a full update */
> > > +    if (s->do_full_update) {
> > > +        s->do_full_update = 0;
> > > +        full_update = 1;
> > > +    }
> > > +
> > >      /* draw each line according to conditions */
> > >      snap = memory_region_snapshot_and_clear_dirty(&s->local_mem_region,
> > >                offset, width * height * src_bpp, DIRTY_MEMORY_VGA);
> > 
> > 
> 

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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