On Mon, 26 Jan 2026, Chad Jablonski wrote:
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.
OK we don't need to care about aux scissors until we find something that
needs it. I was just wondering if SC_* is always applied. There are some
bits in DP_GUI_MASTER_CNTL for GMC_SRC_CLIPPING and GMC_DST_CLIPPING but
those seem to only control using default values instead of normal
registers (or rather reset from defaults as you've found).
Regards,
BALATON Zoltan
+ 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!
