drm/amd/display: Force p-state disallow if leaving no plane config

[ 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>

diff --git a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
index a2e1ca3..2c4bcbc 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
@@ -1792,6 +1792,8 @@ 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;
 
        /* Carry over GSL groups in case the context is changing. */
        for (i = 0; i < dc->res_pool->pipe_count; i++) {
@@ -1815,6 +1817,20 @@ 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],
@@ -1962,6 +1978,10 @@ 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];