dcn20_validate_bandwidth_fp() is invoked while FPU access has been
enabled. FPU access requires disabling preemption even on PREEMPT_RT.
It is not possible to allocate memory with disabled preemption even with
GFP_ATOMIC on PREEMPT_RT.

Move the memory allocation before FPU access is enabled.
To preserve previous "clean" state of "pipes" add a memset() before the
second invocation of dcn20_validate_bandwidth_internal() where the
variable is used.

Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
---
 .../drm/amd/display/dc/dcn20/dcn20_resource.c    | 10 +++++++++-
 .../gpu/drm/amd/display/dc/dml/dcn20/dcn20_fpu.c | 16 +++++++---------
 .../gpu/drm/amd/display/dc/dml/dcn20/dcn20_fpu.h |  5 ++---
 3 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c 
b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c
index d587f807dfd7c..5036a3e608324 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c
@@ -2141,9 +2141,17 @@ bool dcn20_validate_bandwidth(struct dc *dc, struct 
dc_state *context,
                bool fast_validate)
 {
        bool voltage_supported;
+       display_e2e_pipe_params_st *pipes;
+
+       pipes = kcalloc(dc->res_pool->pipe_count, 
sizeof(display_e2e_pipe_params_st), GFP_KERNEL);
+       if (!pipes)
+               return false;
+
        DC_FP_START();
-       voltage_supported = dcn20_validate_bandwidth_fp(dc, context, 
fast_validate);
+       voltage_supported = dcn20_validate_bandwidth_fp(dc, context, 
fast_validate, pipes);
        DC_FP_END();
+
+       kfree(pipes);
        return voltage_supported;
 }
 
diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn20/dcn20_fpu.c 
b/drivers/gpu/drm/amd/display/dc/dml/dcn20/dcn20_fpu.c
index 8b2038162a7e1..2ad92497b9bf2 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn20/dcn20_fpu.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn20/dcn20_fpu.c
@@ -1923,7 +1923,7 @@ void dcn20_patch_bounding_box(struct dc *dc, struct 
_vcs_dpi_soc_bounding_box_st
 }
 
 static bool dcn20_validate_bandwidth_internal(struct dc *dc, struct dc_state 
*context,
-               bool fast_validate)
+               bool fast_validate, display_e2e_pipe_params_st *pipes)
 {
        bool out = false;
 
@@ -1932,7 +1932,6 @@ static bool dcn20_validate_bandwidth_internal(struct dc 
*dc, struct dc_state *co
        int vlevel = 0;
        int pipe_split_from[MAX_PIPES];
        int pipe_cnt = 0;
-       display_e2e_pipe_params_st *pipes = kzalloc(dc->res_pool->pipe_count * 
sizeof(display_e2e_pipe_params_st), GFP_ATOMIC);
        DC_LOGGER_INIT(dc->ctx->logger);
 
        BW_VAL_TRACE_COUNT();
@@ -1967,16 +1966,14 @@ static bool dcn20_validate_bandwidth_internal(struct dc 
*dc, struct dc_state *co
        out = false;
 
 validate_out:
-       kfree(pipes);
 
        BW_VAL_TRACE_FINISH();
 
        return out;
 }
 
-bool dcn20_validate_bandwidth_fp(struct dc *dc,
-                                struct dc_state *context,
-                                bool fast_validate)
+bool dcn20_validate_bandwidth_fp(struct dc *dc, struct dc_state *context,
+                                bool fast_validate, display_e2e_pipe_params_st 
*pipes)
 {
        bool voltage_supported = false;
        bool full_pstate_supported = false;
@@ -1995,11 +1992,11 @@ bool dcn20_validate_bandwidth_fp(struct dc *dc,
        ASSERT(context != dc->current_state);
 
        if (fast_validate) {
-               return dcn20_validate_bandwidth_internal(dc, context, true);
+               return dcn20_validate_bandwidth_internal(dc, context, true, 
pipes);
        }
 
        // Best case, we support full UCLK switch latency
-       voltage_supported = dcn20_validate_bandwidth_internal(dc, context, 
false);
+       voltage_supported = dcn20_validate_bandwidth_internal(dc, context, 
false, pipes);
        full_pstate_supported = 
context->bw_ctx.bw.dcn.clk.p_state_change_support;
 
        if (context->bw_ctx.dml.soc.dummy_pstate_latency_us == 0 ||
@@ -2011,7 +2008,8 @@ bool dcn20_validate_bandwidth_fp(struct dc *dc,
        // Fallback: Try to only support G6 temperature read latency
        context->bw_ctx.dml.soc.dram_clock_change_latency_us = 
context->bw_ctx.dml.soc.dummy_pstate_latency_us;
 
-       voltage_supported = dcn20_validate_bandwidth_internal(dc, context, 
false);
+       memset(pipes, 0, dc->res_pool->pipe_count * 
sizeof(display_e2e_pipe_params_st));
+       voltage_supported = dcn20_validate_bandwidth_internal(dc, context, 
false, pipes);
        dummy_pstate_supported = 
context->bw_ctx.bw.dcn.clk.p_state_change_support;
 
        if (voltage_supported && (dummy_pstate_supported || 
!(context->stream_count))) {
diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn20/dcn20_fpu.h 
b/drivers/gpu/drm/amd/display/dc/dml/dcn20/dcn20_fpu.h
index a81a0b9e68842..b6c34198ddc86 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn20/dcn20_fpu.h
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn20/dcn20_fpu.h
@@ -61,9 +61,8 @@ void dcn20_update_bounding_box(struct dc *dc,
                               unsigned int num_states);
 void dcn20_patch_bounding_box(struct dc *dc,
                              struct _vcs_dpi_soc_bounding_box_st *bb);
-bool dcn20_validate_bandwidth_fp(struct dc *dc,
-                                struct dc_state *context,
-                                bool fast_validate);
+bool dcn20_validate_bandwidth_fp(struct dc *dc, struct dc_state *context,
+                                bool fast_validate, display_e2e_pipe_params_st 
*pipes);
 void dcn20_fpu_set_wm_ranges(int i,
                             struct pp_smu_wm_range_sets *ranges,
                             struct _vcs_dpi_soc_bounding_box_st *loaded_bb);
-- 
2.40.1

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