>
> Is there a bit somewhere that enables clipping that needs to be checked
> here? Or are the sc regs always expected to have meaningful values and
> clipping is always done?
>
There isn't an enable bit for the primary scissor registers. There are however
enable bits for the aux clipping registers in AUX_SC_CNTL. In fact the xorg
r128 driver when initialized sets AUX_SC_CNTL to 0x0 (all aux clipping
disabled) just before also setting DEFAULT_SC_BOTTOM_RIGHT and SC_BOTTOM_RIGHT
to their max values.
We will need to handle the aux clipping eventually but this patch only
implements the primary clipping registers.
>> + if (!vis_dst.height || !vis_dst.width) {
>> + /* Nothing to do, completely clipped */
>
> It's less clear what vis means so maybe this comment could clarify by
> saying Nothing is visible, completely clipped.
>
I'll make this more clear!
