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drm/amd/display: take max dsc stream bandwidth overhead into account

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[why]
As hardware team suggested that we need to add a max dsc bw overhead
into existing stream bandwidth when DSC is used.
The formula as below:

max_dsc_bw_overhead =
v_addressable * slice_count * 256 bit * pixel clock / v_total / h_total

effective stream bandwidth = pixel clock * bpp

stream bandwidth = effective stream bandwidth + dsc stream overhead

Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Reviewed-by: Eric Bernstein <Eric.Bernstein@amd.com>
Acked-by: Wayne Lin <waynelin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Wenjing Liu
2021-04-09 14:55:18 -04:00
committed by Alex Deucher
parent abf1f863e0
commit 642d3a2bf2
5 changed files with 94 additions and 76 deletions
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43
drivers/gpu/drm/amd/display/dc/dsc/rc_calc.c
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@@ -284,26 +284,6 @@ static u32 _do_bytes_per_pixel_calc(int slice_width, u16 drm_bpp,
return bytes_per_pixel;
}
static u32 _do_calc_dsc_bpp_x16(u32 stream_bandwidth_kbps, u32 pix_clk_100hz,
u32 bpp_increment_div)
{
u32 dsc_target_bpp_x16;
float f_dsc_target_bpp;
float f_stream_bandwidth_100bps;
// bpp_increment_div is actually precision
u32 precision = bpp_increment_div;
f_stream_bandwidth_100bps = stream_bandwidth_kbps * 10.0f;
f_dsc_target_bpp = f_stream_bandwidth_100bps / pix_clk_100hz;
// Round down to the nearest precision stop to bring it into DSC spec
// range
dsc_target_bpp_x16 = (u32)(f_dsc_target_bpp * precision);
dsc_target_bpp_x16 = (dsc_target_bpp_x16 * 16) / precision;
return dsc_target_bpp_x16;
}
/**
* calc_rc_params - reads the user's cmdline mode
* @rc: DC internal DSC parameters
@@ -367,26 +347,3 @@ u32 calc_dsc_bytes_per_pixel(const struct drm_dsc_config *pps)
DC_FP_END();
return ret;
}
/**
* calc_dsc_bpp_x16 - retrieve the dsc bits per pixel
* @stream_bandwidth_kbps:
* @pix_clk_100hz:
* @bpp_increment_div:
*
* Calculate the total of bits per pixel for DSC configuration.
*
* @note This calculation requires float point operation, most of it executes
* under kernel_fpu_{begin,end}.
*/
u32 calc_dsc_bpp_x16(u32 stream_bandwidth_kbps, u32 pix_clk_100hz,
u32 bpp_increment_div)
{
u32 dsc_bpp;
DC_FP_START();
dsc_bpp = _do_calc_dsc_bpp_x16(stream_bandwidth_kbps, pix_clk_100hz,
bpp_increment_div);
DC_FP_END();
return dsc_bpp;
}