Commit 062c2e43 authored by Alex Deucher's avatar Alex Deucher

drm/radeon: use 64-bit math to calculate CTS values for audio (v2)

Avoid losing precision.  See bug:
https://bugs.freedesktop.org/show_bug.cgi?id=69675

v2: fix math as per Anssi's comments.
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent aaed41ec
......@@ -75,8 +75,15 @@ static const struct radeon_hdmi_acr r600_hdmi_predefined_acr[] = {
*/
static void r600_hdmi_calc_cts(uint32_t clock, int *CTS, int N, int freq)
{
if (*CTS == 0)
*CTS = clock * N / (128 * freq) * 1000;
u64 n;
u32 d;
if (*CTS == 0) {
n = (u64)clock * (u64)N * 1000ULL;
d = 128 * freq;
do_div(n, d);
*CTS = n;
}
DRM_DEBUG("Using ACR timing N=%d CTS=%d for frequency %d\n",
N, *CTS, freq);
}
......
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