[PATCH] drm/amd/display: don't call dm_pp_ function from an fpu block

[Deucher, Alexander]

Acked-by: Alex Deucher <alexander.deucher at amd.com>
________________________________
From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> on behalf of Harry Wentland <harry.wentland at amd.com>
Sent: Friday, February 22, 2019 10:39 AM
To: amd-gfx at lists.freedesktop.org
Cc: robdclark at gmail.com; Wentland, Harry; stable at vger.kernel.org
Subject: [PATCH] drm/amd/display: don't call dm_pp_ function from an fpu block

Powerplay functions called from dm_pp_* functions tend to do a
mutex_lock which isn't safe to do inside a kernel_fpu_begin/end block as
those will disable/enable preemption.

Rearrange the dm_pp_get_clock_levels_by_type_with_voltage calls to make
sure they happen outside of kernel_fpu_begin/end.

Cc: stable at vger.kernel.org
Signed-off-by: Harry Wentland <harry.wentland at amd.com>
---
 drivers/gpu/drm/amd/display/dc/calcs/dcn_calcs.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/calcs/dcn_calcs.c b/drivers/gpu/drm/amd/display/dc/calcs/dcn_calcs.c
index 2a807b9f77f7..5955634f6e27 100644
--- a/drivers/gpu/drm/amd/display/dc/calcs/dcn_calcs.c
+++ b/drivers/gpu/drm/amd/display/dc/calcs/dcn_calcs.c
@@ -1348,12 +1348,12 @@ void dcn_bw_update_from_pplib(struct dc *dc)
         struct dm_pp_clock_levels_with_voltage fclks = {0}, dcfclks = {0};
         bool res;

-       kernel_fpu_begin();
-
         /* TODO: This is not the proper way to obtain fabric_and_dram_bandwidth, should be min(fclk, memclk) */
         res = dm_pp_get_clock_levels_by_type_with_voltage(
                         ctx, DM_PP_CLOCK_TYPE_FCLK, &fclks);

+       kernel_fpu_begin();
+
         if (res)
                 res = verify_clock_values(&fclks);

@@ -1372,9 +1372,13 @@ void dcn_bw_update_from_pplib(struct dc *dc)
         } else
                 BREAK_TO_DEBUGGER();

+       kernel_fpu_end();
+
         res = dm_pp_get_clock_levels_by_type_with_voltage(
                         ctx, DM_PP_CLOCK_TYPE_DCFCLK, &dcfclks);

+       kernel_fpu_begin();
+
         if (res)
                 res = verify_clock_values(&dcfclks);

--
2.19.1

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