[3.11.y.z extended stable] Patch "drm/radeon: use 64-bit math to calculate CTS values for audio (v2)" has been added to staging queue
Luis Henriques
luis.henriques at canonical.com
Thu Dec 5 11:24:59 UTC 2013
This is a note to let you know that I have just added a patch titled
drm/radeon: use 64-bit math to calculate CTS values for audio (v2)
to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree
which can be found at:
http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Luis
------
>From e45bf51dd38635f8ef3c3d9df116679913d5a4ff Mon Sep 17 00:00:00 2001
From: Alex Deucher <alexander.deucher at amd.com>
Date: Fri, 27 Sep 2013 18:09:54 -0400
Subject: 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 at amd.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
drivers/gpu/drm/radeon/r600_hdmi.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/radeon/r600_hdmi.c b/drivers/gpu/drm/radeon/r600_hdmi.c
index a74c2aa..14e19aa 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);
}
--
1.8.3.2
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