Commit ae45bbc2 authored by Mario Kleiner's avatar Mario Kleiner Committed by Alex Deucher

drm/radeon: Avoid overflows/divide-by-zero in latency_watermark calculations.

At dot clocks > approx. 250 Mhz, some of these calcs will overflow and
cause miscalculation of latency watermarks, and for some overflows also
divide-by-zero driver crash. Make calcs more overflow resistant.

This is a direct port of the corresponding patch from amdgpu-kms,
copy-paste for cik from dce-8 and si from dce-6, with a slightly
simpler variant for evergreen dce-4/5.

Only tested on DCE-4 evergreen with a Radeon HD-5770.
Signed-off-by: default avatarMario Kleiner <mario.kleiner.de@gmail.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent effaf848
...@@ -9150,23 +9150,10 @@ static u32 dce8_latency_watermark(struct dce8_wm_params *wm) ...@@ -9150,23 +9150,10 @@ static u32 dce8_latency_watermark(struct dce8_wm_params *wm)
a.full = dfixed_const(available_bandwidth); a.full = dfixed_const(available_bandwidth);
b.full = dfixed_const(wm->num_heads); b.full = dfixed_const(wm->num_heads);
a.full = dfixed_div(a, b); a.full = dfixed_div(a, b);
tmp = div_u64((u64) dmif_size * (u64) wm->disp_clk, mc_latency + 512);
tmp = min(dfixed_trunc(a), tmp);
b.full = dfixed_const(mc_latency + 512); lb_fill_bw = min(tmp, wm->disp_clk * wm->bytes_per_pixel / 1000);
c.full = dfixed_const(wm->disp_clk);
b.full = dfixed_div(b, c);
c.full = dfixed_const(dmif_size);
b.full = dfixed_div(c, b);
tmp = min(dfixed_trunc(a), dfixed_trunc(b));
b.full = dfixed_const(1000);
c.full = dfixed_const(wm->disp_clk);
b.full = dfixed_div(c, b);
c.full = dfixed_const(wm->bytes_per_pixel);
b.full = dfixed_mul(b, c);
lb_fill_bw = min(tmp, dfixed_trunc(b));
a.full = dfixed_const(max_src_lines_per_dst_line * wm->src_width * wm->bytes_per_pixel); a.full = dfixed_const(max_src_lines_per_dst_line * wm->src_width * wm->bytes_per_pixel);
b.full = dfixed_const(1000); b.full = dfixed_const(1000);
......
...@@ -2188,13 +2188,7 @@ static u32 evergreen_latency_watermark(struct evergreen_wm_params *wm) ...@@ -2188,13 +2188,7 @@ static u32 evergreen_latency_watermark(struct evergreen_wm_params *wm)
b.full = dfixed_const(wm->num_heads); b.full = dfixed_const(wm->num_heads);
a.full = dfixed_div(a, b); a.full = dfixed_div(a, b);
b.full = dfixed_const(1000); lb_fill_bw = min(dfixed_trunc(a), wm->disp_clk * wm->bytes_per_pixel / 1000);
c.full = dfixed_const(wm->disp_clk);
b.full = dfixed_div(c, b);
c.full = dfixed_const(wm->bytes_per_pixel);
b.full = dfixed_mul(b, c);
lb_fill_bw = min(dfixed_trunc(a), dfixed_trunc(b));
a.full = dfixed_const(max_src_lines_per_dst_line * wm->src_width * wm->bytes_per_pixel); a.full = dfixed_const(max_src_lines_per_dst_line * wm->src_width * wm->bytes_per_pixel);
b.full = dfixed_const(1000); b.full = dfixed_const(1000);
......
...@@ -2204,23 +2204,10 @@ static u32 dce6_latency_watermark(struct dce6_wm_params *wm) ...@@ -2204,23 +2204,10 @@ static u32 dce6_latency_watermark(struct dce6_wm_params *wm)
a.full = dfixed_const(available_bandwidth); a.full = dfixed_const(available_bandwidth);
b.full = dfixed_const(wm->num_heads); b.full = dfixed_const(wm->num_heads);
a.full = dfixed_div(a, b); a.full = dfixed_div(a, b);
tmp = div_u64((u64) dmif_size * (u64) wm->disp_clk, mc_latency + 512);
tmp = min(dfixed_trunc(a), tmp);
b.full = dfixed_const(mc_latency + 512); lb_fill_bw = min(tmp, wm->disp_clk * wm->bytes_per_pixel / 1000);
c.full = dfixed_const(wm->disp_clk);
b.full = dfixed_div(b, c);
c.full = dfixed_const(dmif_size);
b.full = dfixed_div(c, b);
tmp = min(dfixed_trunc(a), dfixed_trunc(b));
b.full = dfixed_const(1000);
c.full = dfixed_const(wm->disp_clk);
b.full = dfixed_div(c, b);
c.full = dfixed_const(wm->bytes_per_pixel);
b.full = dfixed_mul(b, c);
lb_fill_bw = min(tmp, dfixed_trunc(b));
a.full = dfixed_const(max_src_lines_per_dst_line * wm->src_width * wm->bytes_per_pixel); a.full = dfixed_const(max_src_lines_per_dst_line * wm->src_width * wm->bytes_per_pixel);
b.full = dfixed_const(1000); b.full = dfixed_const(1000);
......
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