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| author | Alex Deucher <alexander.deucher@amd.com> | 2013-09-27 18:09:54 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-12-04 10:57:34 -0800 |
| commit | 78c3ae2cb101bc10f3b9cc851e826484246088e1 (patch) | |
| tree | ef3b2c39e5dfcca4cbf19983d0d509cb0bab3b92 /drivers/gpu/drm/radeon/r600_hdmi.c | |
| parent | b18cd40e6228da53f2781f37f9b94a1930c6ee9c (diff) | |
| download | linux-3.10-78c3ae2cb101bc10f3b9cc851e826484246088e1.tar.gz linux-3.10-78c3ae2cb101bc10f3b9cc851e826484246088e1.tar.bz2 linux-3.10-78c3ae2cb101bc10f3b9cc851e826484246088e1.zip | |
drm/radeon: use 64-bit math to calculate CTS values for audio (v2)
commit 062c2e4363451d49ef840232fe65e8bff0dde2a5 upstream.
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: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/gpu/drm/radeon/r600_hdmi.c')
| -rw-r--r-- | drivers/gpu/drm/radeon/r600_hdmi.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/gpu/drm/radeon/r600_hdmi.c b/drivers/gpu/drm/radeon/r600_hdmi.c index 0efe2a93ca9..322e42737ef 100644 --- a/drivers/gpu/drm/radeon/r600_hdmi.c +++ b/drivers/gpu/drm/radeon/r600_hdmi.c @@ -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); } |