Re: [PATCH 2/6] drm/amd/display: Reduce frame size in the bouding box for DCN20

[Harry Wentland <harry.wentland@amd.com>]

On 2022-06-03 14:50, Rodrigo Siqueira wrote:
> GCC throw warnings for the function dcn20_update_bounding_box due to its
> frame size that looks like this:
> 
>  error: the frame size of 1936 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
> 
> This commit fixes this issue by eliminating an intermediary variable
> that creates a large array.
> 
> Cc: Stephen Rothwell <sfr@canb.auug.org.au>
> Cc: Hamza Mahfooz <hamza.mahfooz@amd.com>
> Cc: Aurabindo Pillai <aurabindo.pillai@amd.com>
> Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>

Reviewed-by: Harry Wentland <harry.wentland@amd.com>

Harry

> ---
>  .../drm/amd/display/dc/dml/dcn20/dcn20_fpu.c  | 38 +++++++++----------
>  1 file changed, 18 insertions(+), 20 deletions(-)
> 
> 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 eeec40f6fd0a..d9cc178f6980 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
> @@ -1456,21 +1456,20 @@ void dcn20_calculate_wm(
>  void dcn20_update_bounding_box(struct dc *dc, struct _vcs_dpi_soc_bounding_box_st *bb,
>  		struct pp_smu_nv_clock_table *max_clocks, unsigned int *uclk_states, unsigned int num_states)
>  {
> -	struct _vcs_dpi_voltage_scaling_st calculated_states[DC__VOLTAGE_STATES];
> -	int i;
>  	int num_calculated_states = 0;
>  	int min_dcfclk = 0;
> +	int i;
>  
>  	dc_assert_fp_enabled();
>  
>  	if (num_states == 0)
>  		return;
>  
> -	memset(calculated_states, 0, sizeof(calculated_states));
> +	memset(bb->clock_limits, 0, sizeof(bb->clock_limits));
>  
> -	if (dc->bb_overrides.min_dcfclk_mhz > 0)
> +	if (dc->bb_overrides.min_dcfclk_mhz > 0) {
>  		min_dcfclk = dc->bb_overrides.min_dcfclk_mhz;
> -	else {
> +	} else {
>  		if (ASICREV_IS_NAVI12_P(dc->ctx->asic_id.hw_internal_rev))
>  			min_dcfclk = 310;
>  		else
> @@ -1481,36 +1480,35 @@ void dcn20_update_bounding_box(struct dc *dc, struct _vcs_dpi_soc_bounding_box_s
>  
>  	for (i = 0; i < num_states; i++) {
>  		int min_fclk_required_by_uclk;
> -		calculated_states[i].state = i;
> -		calculated_states[i].dram_speed_mts = uclk_states[i] * 16 / 1000;
> +		bb->clock_limits[i].state = i;
> +		bb->clock_limits[i].dram_speed_mts = uclk_states[i] * 16 / 1000;
>  
>  		// FCLK:UCLK ratio is 1.08
>  		min_fclk_required_by_uclk = div_u64(((unsigned long long)uclk_states[i]) * 1080,
>  			1000000);
>  
> -		calculated_states[i].fabricclk_mhz = (min_fclk_required_by_uclk < min_dcfclk) ?
> +		bb->clock_limits[i].fabricclk_mhz = (min_fclk_required_by_uclk < min_dcfclk) ?
>  				min_dcfclk : min_fclk_required_by_uclk;
>  
> -		calculated_states[i].socclk_mhz = (calculated_states[i].fabricclk_mhz > max_clocks->socClockInKhz / 1000) ?
> -				max_clocks->socClockInKhz / 1000 : calculated_states[i].fabricclk_mhz;
> +		bb->clock_limits[i].socclk_mhz = (bb->clock_limits[i].fabricclk_mhz > max_clocks->socClockInKhz / 1000) ?
> +				max_clocks->socClockInKhz / 1000 : bb->clock_limits[i].fabricclk_mhz;
>  
> -		calculated_states[i].dcfclk_mhz = (calculated_states[i].fabricclk_mhz > max_clocks->dcfClockInKhz / 1000) ?
> -				max_clocks->dcfClockInKhz / 1000 : calculated_states[i].fabricclk_mhz;
> +		bb->clock_limits[i].dcfclk_mhz = (bb->clock_limits[i].fabricclk_mhz > max_clocks->dcfClockInKhz / 1000) ?
> +				max_clocks->dcfClockInKhz / 1000 : bb->clock_limits[i].fabricclk_mhz;
>  
> -		calculated_states[i].dispclk_mhz = max_clocks->displayClockInKhz / 1000;
> -		calculated_states[i].dppclk_mhz = max_clocks->displayClockInKhz / 1000;
> -		calculated_states[i].dscclk_mhz = max_clocks->displayClockInKhz / (1000 * 3);
> +		bb->clock_limits[i].dispclk_mhz = max_clocks->displayClockInKhz / 1000;
> +		bb->clock_limits[i].dppclk_mhz = max_clocks->displayClockInKhz / 1000;
> +		bb->clock_limits[i].dscclk_mhz = max_clocks->displayClockInKhz / (1000 * 3);
>  
> -		calculated_states[i].phyclk_mhz = max_clocks->phyClockInKhz / 1000;
> +		bb->clock_limits[i].phyclk_mhz = max_clocks->phyClockInKhz / 1000;
>  
>  		num_calculated_states++;
>  	}
>  
> -	calculated_states[num_calculated_states - 1].socclk_mhz = max_clocks->socClockInKhz / 1000;
> -	calculated_states[num_calculated_states - 1].fabricclk_mhz = max_clocks->socClockInKhz / 1000;
> -	calculated_states[num_calculated_states - 1].dcfclk_mhz = max_clocks->dcfClockInKhz / 1000;
> +	bb->clock_limits[num_calculated_states - 1].socclk_mhz = max_clocks->socClockInKhz / 1000;
> +	bb->clock_limits[num_calculated_states - 1].fabricclk_mhz = max_clocks->socClockInKhz / 1000;
> +	bb->clock_limits[num_calculated_states - 1].dcfclk_mhz = max_clocks->dcfClockInKhz / 1000;
>  
> -	memcpy(bb->clock_limits, calculated_states, sizeof(bb->clock_limits));
>  	bb->num_states = num_calculated_states;
>  
>  	// Duplicate the last state, DML always an extra state identical to max state to work