[PATCH AUTOSEL 6.7 51/88] drm/amd/display: Force p-state disallow if leaving no plane config

Sasha Levin
2024-01-22T14:59:03Z

From: Alvin Lee <alvin.lee2@amd.com>

[ Upstream commit 9a902a9073c287353e25913c0761bfed49d75a88 ]

[Description]
- When we're in a no plane config, DCN is always asserting
P-State allow
- This creates a scenario where the P-State blackout can start
just as VUPDATE takes place and transitions the DCN config to
a one where one or more HUBP's are active which can result in
underflow
- To fix this issue, force p-state disallow and unforce after
the transition from no planes case -> one or more planes active

Reviewed-by: Samson Tam <samson.tam@amd.com>
Acked-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alvin Lee <alvin.lee2@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../amd/display/dc/hwss/dcn20/dcn20_hwseq.c | 20 +++++++++++++++++++
1 file changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
index 608221b0dd5d..c3c83178eb1e 100644
--- a/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
@@ -1877,6 +1877,8 @@ void dcn20_program_front_end_for_ctx(
int i;
struct dce_hwseq *hws = dc->hwseq;
DC_LOGGER_INIT(dc->ctx->logger);
+ unsigned int prev_hubp_count = 0;
+ unsigned int hubp_count = 0;

if (resource_is_pipe_topology_changed(dc->current_state, context))
resource_log_pipe_topology_update(dc, context);
@@ -1894,6 +1896,20 @@ void dcn20_program_front_end_for_ctx(
}
}

+ for (i = 0; i < dc->res_pool->pipe_count; i++) {
+ if (dc->current_state->res_ctx.pipe_ctx[i].plane_state)
+ prev_hubp_count++;
+ if (context->res_ctx.pipe_ctx[i].plane_state)
+ hubp_count++;
+ }
+
+ if (prev_hubp_count == 0 && hubp_count > 0) {
+ if (dc->res_pool->hubbub->funcs->force_pstate_change_control)
+ dc->res_pool->hubbub->funcs->force_pstate_change_control(
+ dc->res_pool->hubbub, true, false);
+ udelay(500);
+ }
+
/* Set pipe update flags and lock pipes */
for (i = 0; i < dc->res_pool->pipe_count; i++)
dcn20_detect_pipe_changes(&dc->current_state->res_ctx.pipe_ctx[i],
@@ -2039,6 +2055,10 @@ void dcn20_post_unlock_program_front_end(
}
}

+ if (dc->res_pool->hubbub->funcs->force_pstate_change_control)
+ dc->res_pool->hubbub->funcs->force_pstate_change_control(
+ dc->res_pool->hubbub, false, false);
+
for (i = 0; i < dc->res_pool->pipe_count; i++) {
struct pipe_ctx *pipe = &context->res_ctx.pipe_ctx[i];

--
2.43.0