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

[Rob Clark]

On Fri, Feb 22, 2019 at 10:39 AM Harry Wentland <harry.wentland at amd.com> wrote:
>
> 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>

Tested-by: Rob Clark <robdclark at gmail.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
>