linux-kernel - [PATCH 4.19 272/280] drm/amd/display: dont call dm_pp

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Date:   Fri, 22 Mar 2019 12:17:05 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Alex Deucher <alexander.deucher@....com>,
        Harry Wentland <harry.wentland@....com>
Subject: [PATCH 4.19 272/280] drm/amd/display: dont call dm_pp_ function from an fpu block

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Harry Wentland <harry.wentland@....com>

commit 59d3191f14dc18881fec1172c7096b7863622803 upstream.

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@...r.kernel.org
Acked-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Harry Wentland <harry.wentland@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/amd/display/dc/calcs/dcn_calcs.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/calcs/dcn_calcs.c
+++ b/drivers/gpu/drm/amd/display/dc/calcs/dcn_calcs.c
@@ -1347,12 +1347,12 @@ void dcn_bw_update_from_pplib(struct 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);
 
@@ -1371,9 +1371,13 @@ void dcn_bw_update_from_pplib(struct 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);