On Wed, 31 Dec 2025, Chad Jablonski wrote:
The PM4_STAT register largely mirrors the flags of the GUI_STAT
register. The exception is that the low bits of PM4_STAT reflect the
remaining slots in the CCE FIFO instead of the GUI FIFO.
This implements a very incomplete set of common flags
(MICRO_BUSY and GUI_ACTIVE) and the PM4_STAT register.
Signed-off-by: Chad Jablonski <[email protected]>
---
hw/display/ati.c | 16 +++++++++++++++-
hw/display/ati_cce.c | 38 ++++++++++++++++++++++++++++++++++++++
hw/display/ati_cce.h | 3 +++
hw/display/ati_regs.h | 1 +
4 files changed, 57 insertions(+), 1 deletion(-)
diff --git a/hw/display/ati.c b/hw/display/ati.c
index 9edde2b0bc..3f31a76b72 100644
--- a/hw/display/ati.c
+++ b/hw/display/ati.c
@@ -276,6 +276,16 @@ static inline uint64_t ati_reg_read_offs(uint32_t reg, int
offs,
}
}
+static uint32_t ati_common_stat(ATIVGAState *s)
+{
+ /* TODO: This is _very_ naive. It will evolve. */
+ uint32_t micro_busy = ati_cce_micro_busy(&s->cce.cur_packet) ?
+ MICRO_BUSY : 0;
+ /* GUI_ACTIVE is the OR of all other status flags */
+ uint32_t gui_active = micro_busy ? GUI_ACTIVE : 0;
+ return gui_active | micro_busy;
+}
+
static uint64_t ati_mm_read(void *opaque, hwaddr addr, unsigned int size)
{
ATIVGAState *s = opaque;
@@ -383,7 +393,7 @@ static uint64_t ati_mm_read(void *opaque, hwaddr addr,
unsigned int size)
break;
case RBBM_STATUS:
case GUI_STAT:
- val = 64; /* free CMDFIFO entries */
+ val = ati_common_stat(s) | 64; /* free CMDFIFO entries */
break;
case CRTC_H_TOTAL_DISP:
val = s->regs.crtc_h_total_disp;
@@ -543,6 +553,10 @@ static uint64_t ati_mm_read(void *opaque, hwaddr addr,
unsigned int size)
case PM4_MICRO_CNTL:
val = s->cce.freerun ? PM4_MICRO_FREERUN : 0;
break;
+ case PM4_STAT: {
+ val = ati_common_stat(s) | ati_cce_fifo_cnt(&s->cce);
+ break;
+ }
default:
break;
}
diff --git a/hw/display/ati_cce.c b/hw/display/ati_cce.c
index 62a88a54df..3d35b0e857 100644
--- a/hw/display/ati_cce.c
+++ b/hw/display/ati_cce.c
@@ -11,6 +11,24 @@
#include "ati_int.h"
#include "trace.h"
+static uint32_t
+ati_cce_fifo_max(uint8_t mode)
+{
+ switch (mode) {
+ case PM4_BUFFER_CNTL_NONPM4...PM4_BUFFER_CNTL_192BM:
You could move this down before default: then no separate case is needed
for it as this seems to be the default and other cases are real cases.
+ return 192;
+ case PM4_BUFFER_CNTL_128PIO_64INDBM...PM4_BUFFER_CNTL_128BM_64INDBM:
+ return 128;
+ case PM4_BUFFER_CNTL_64PIO_128INDBM...PM4_BUFFER_CNTL_64PIO_64VCBM_64INDBM:
+ /* fall through */
Comment not needed here.
Sorry that I cannot give more advice than such small style comments but I
don't know these GPUs that well and have no time to dig into it so I can
only give generic ideas and try to review it. I still need to check the
host data series. Thanks a lot for this great contribution, keep up the
good work.
Regards,
BALATON Zoltan
+ case PM4_BUFFER_CNTL_64PIO_64VCPIO_64INPIO:
+ return 64;
+ default:
+ /* Undocumented but testing shows this returns 192 otherwise */
+ return 192;
+ }
+}
+
static inline uint32_t
ati_cce_data_packets_remaining(const ATIPM4PacketState *p)
{
@@ -154,3 +172,23 @@ ati_cce_receive_data(ATIVGAState *s, uint32_t data)
}
ati_cce_process_packet_data(s, data);
}
+
+bool
+ati_cce_micro_busy(const ATIPM4PacketState *p)
+{
+ uint32_t remaining = ati_cce_data_packets_remaining(p);
+ if (remaining > 0) {
+ return true;
+ }
+ return false;
+}
+
+uint32_t
+ati_cce_fifo_cnt(const ATICCEState *c)
+{
+ /*
+ * This should return the available slots. Given that commands are
+ * processed immediately this returns the fifo max for now.
+ */
+ return ati_cce_fifo_max(c->buffer_mode);
+}
diff --git a/hw/display/ati_cce.h b/hw/display/ati_cce.h
index b6ad21f47e..12aede6ecc 100644
--- a/hw/display/ati_cce.h
+++ b/hw/display/ati_cce.h
@@ -85,4 +85,7 @@ typedef struct ATICCEState {
} ATICCEState;
void ati_cce_receive_data(ATIVGAState *s, uint32_t data);
+bool ati_cce_micro_busy(const ATIPM4PacketState *p);
+uint32_t ati_cce_fifo_cnt(const ATICCEState *c);
+
#endif /* ATI_CCE_H */
diff --git a/hw/display/ati_regs.h b/hw/display/ati_regs.h
index d7118449f5..841019ac7b 100644
--- a/hw/display/ati_regs.h
+++ b/hw/display/ati_regs.h
@@ -280,6 +280,7 @@
/* CONSTANTS */
#define GUI_ACTIVE 0x80000000
+#define MICRO_BUSY 0x00020000
#define ENGINE_IDLE 0x0
#define PLL_WR_EN 0x00000080
