drm/amd/display: Write flip addr to scratch reg for subvp

[Description]
SubVP needs to "calculate" the earliest in use META address
by using the current primary / meta addresses, but this leads
to a race condition where FW and driver can read/write the
address at the same time and intermittently produce inconsistent
address offsets. To mitigate this issue without locking (too slow),
save each surface flip addr into scratch registers and use this
to keep track of the earliest in use META addres.

Reviewed-by: Jun Lei <jun.lei@amd.com>
Acked-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Alvin Lee <alvin.lee2@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

4 files changed, 64 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/display/dmub/dmub_srv.h b/drivers/gpu/drm/amd/display/dmub/dmub_srv.h
index 43676c1c81d9..e7a50cbf2540 100644
--- a/drivers/gpu/drm/amd/display/dmub/dmub_srv.h
+++ b/drivers/gpu/drm/amd/display/dmub/dmub_srv.h
@@ -401,6 +401,8 @@ struct dmub_srv_hw_funcs {
 
 	bool (*should_detect)(struct dmub_srv *dmub);
 	void (*init_reg_offsets)(struct dmub_srv *dmub, struct dc_context *ctx);
+
+	void (*subvp_save_surf_addr)(struct dmub_srv *dmub, const struct dc_plane_address *addr, uint8_t subvp_index);
 };
 
 /**
@@ -835,6 +837,21 @@ enum dmub_status dmub_srv_wait_for_inbox0_ack(struct dmub_srv *dmub, uint32_t ti
  */
 enum dmub_status dmub_srv_clear_inbox0_ack(struct dmub_srv *dmub);
 
+/**
+ * dmub_srv_subvp_save_surf_addr() - Save primary and meta address for subvp on each flip
+ * @dmub: The dmub service
+ * @addr: The surface address to be programmed on the current flip
+ * @subvp_index: Index of subvp pipe, indicates which subvp pipe the address should be saved for
+ *
+ * Function to save the surface flip addr into scratch registers. This is to fix a race condition
+ * between FW and driver reading / writing to the surface address at the same time. This is
+ * required because there is no EARLIEST_IN_USE_META.
+ *
+ * Return:
+ *   void
+ */
+void dmub_srv_subvp_save_surf_addr(struct dmub_srv *dmub, const struct dc_plane_address *addr, uint8_t subvp_index);
+
 #if defined(__cplusplus)
 }
 #endif
diff --git a/drivers/gpu/drm/amd/display/dmub/src/dmub_dcn32.c b/drivers/gpu/drm/amd/display/dmub/src/dmub_dcn32.c
index 8f427047ac40..2daa1e0c8061 100644
--- a/drivers/gpu/drm/amd/display/dmub/src/dmub_dcn32.c
+++ b/drivers/gpu/drm/amd/display/dmub/src/dmub_dcn32.c
@@ -27,6 +27,7 @@
 #include "dmub_reg.h"
 #include "dmub_dcn32.h"
 #include "dc/dc_types.h"
+#include "dc_hw_types.h"
 
 #include "dcn/dcn_3_2_0_offset.h"
 #include "dcn/dcn_3_2_0_sh_mask.h"
@@ -506,3 +507,32 @@ uint32_t dmub_dcn32_read_inbox0_ack_register(struct dmub_srv *dmub)
 {
 	return REG_READ(DMCUB_SCRATCH17);
 }
+
+void dmub_dcn32_save_surf_addr(struct dmub_srv *dmub, const struct dc_plane_address *addr, uint8_t subvp_index)
+{
+	uint32_t index = 0;
+
+	if (subvp_index == 0) {
+		index = REG_READ(DMCUB_SCRATCH15);
+		if (index) {
+			REG_WRITE(DMCUB_SCRATCH9, addr->grph.addr.low_part);
+			REG_WRITE(DMCUB_SCRATCH11, addr->grph.meta_addr.low_part);
+		} else {
+			REG_WRITE(DMCUB_SCRATCH12,  addr->grph.addr.low_part);
+			REG_WRITE(DMCUB_SCRATCH13, addr->grph.meta_addr.low_part);
+		}
+		REG_WRITE(DMCUB_SCRATCH15, !index);
+	} else if (subvp_index == 1) {
+		index = REG_READ(DMCUB_SCRATCH23);
+		if (index) {
+			REG_WRITE(DMCUB_SCRATCH18, addr->grph.addr.low_part);
+			REG_WRITE(DMCUB_SCRATCH19, addr->grph.meta_addr.low_part);
+		} else {
+			REG_WRITE(DMCUB_SCRATCH20,  addr->grph.addr.low_part);
+			REG_WRITE(DMCUB_SCRATCH22, addr->grph.meta_addr.low_part);
+		}
+		REG_WRITE(DMCUB_SCRATCH23, !index);
+	} else {
+		return;
+	}
+}
diff --git a/drivers/gpu/drm/amd/display/dmub/src/dmub_dcn32.h b/drivers/gpu/drm/amd/display/dmub/src/dmub_dcn32.h
index 38e47065e00e..b0cd8d29402f 100644
--- a/drivers/gpu/drm/amd/display/dmub/src/dmub_dcn32.h
+++ b/drivers/gpu/drm/amd/display/dmub/src/dmub_dcn32.h
@@ -107,6 +107,12 @@ struct dmub_srv;
 	DMUB_SR(DMCUB_SCRATCH15) \
 	DMUB_SR(DMCUB_SCRATCH16) \
 	DMUB_SR(DMCUB_SCRATCH17) \
+	DMUB_SR(DMCUB_SCRATCH18) \
+	DMUB_SR(DMCUB_SCRATCH19) \
+	DMUB_SR(DMCUB_SCRATCH20) \
+	DMUB_SR(DMCUB_SCRATCH21) \
+	DMUB_SR(DMCUB_SCRATCH22) \
+	DMUB_SR(DMCUB_SCRATCH23) \
 	DMUB_SR(DMCUB_GPINT_DATAIN0) \
 	DMUB_SR(DMCUB_GPINT_DATAIN1) \
 	DMUB_SR(DMCUB_GPINT_DATAOUT) \
@@ -253,6 +259,7 @@ void dmub_dcn32_configure_dmub_in_system_memory(struct dmub_srv *dmub);
 void dmub_dcn32_send_inbox0_cmd(struct dmub_srv *dmub, union dmub_inbox0_data_register data);
 void dmub_dcn32_clear_inbox0_ack_register(struct dmub_srv *dmub);
 uint32_t dmub_dcn32_read_inbox0_ack_register(struct dmub_srv *dmub);
+void dmub_dcn32_save_surf_addr(struct dmub_srv *dmub, const struct dc_plane_address *addr, uint8_t subvp_index);
 
 void dmub_srv_dcn32_regs_init(struct dmub_srv *dmub, struct dc_context *ctx);
 
diff --git a/drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c b/drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c
index 9780c157196c..53464c3e49c1 100644
--- a/drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c
+++ b/drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c
@@ -278,6 +278,7 @@ static bool dmub_srv_hw_setup(struct dmub_srv *dmub, enum dmub_asic asic)
 		funcs->send_inbox0_cmd = dmub_dcn32_send_inbox0_cmd;
 		funcs->clear_inbox0_ack_register = dmub_dcn32_clear_inbox0_ack_register;
 		funcs->read_inbox0_ack_register = dmub_dcn32_read_inbox0_ack_register;
+		funcs->subvp_save_surf_addr = dmub_dcn32_save_surf_addr;
 		funcs->reset = dmub_dcn32_reset;
 		funcs->reset_release = dmub_dcn32_reset_release;
 		funcs->backdoor_load = dmub_dcn32_backdoor_load;
@@ -985,3 +986,12 @@ enum dmub_status dmub_srv_send_inbox0_cmd(struct dmub_srv *dmub,
 	dmub->hw_funcs.send_inbox0_cmd(dmub, data);
 	return DMUB_STATUS_OK;
 }
+
+void dmub_srv_subvp_save_surf_addr(struct dmub_srv *dmub, const struct dc_plane_address *addr, uint8_t subvp_index)
+{
+	if (dmub->hw_funcs.subvp_save_surf_addr) {
+		dmub->hw_funcs.subvp_save_surf_addr(dmub,
+				addr,
+				subvp_index);
+	}
+}