[src/trunk]: src/sys/dev/hdaudio Make round_blocksize satisfy all of

[isaki <isaki%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/b478e95b805f
branches:  trunk
changeset: 930972:b478e95b805f
user:      isaki <isaki%NetBSD.org@localhost>
date:      Sun Apr 19 04:13:09 2020 +0000

description:
Make round_blocksize satisfy all of
- restrictions that existed before merging isaki-audio2 branch.
- better support for 6 channels hardware.
- audio layer's requirement.
This may help PR kern/54474.

diffstat:

 sys/dev/hdaudio/hdafg.c |  43 +++++++++++++++++++++++++++++++++++--------
 1 files changed, 35 insertions(+), 8 deletions(-)

diffs (85 lines):

diff -r 1358a2c86c1a -r b478e95b805f sys/dev/hdaudio/hdafg.c
--- a/sys/dev/hdaudio/hdafg.c   Sun Apr 19 03:52:22 2020 +0000
+++ b/sys/dev/hdaudio/hdafg.c   Sun Apr 19 04:13:09 2020 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: hdafg.c,v 1.21 2020/02/15 03:04:45 isaki Exp $ */
+/* $NetBSD: hdafg.c,v 1.22 2020/04/19 04:13:09 isaki Exp $ */
 
 /*
  * Copyright (c) 2009 Precedence Technologies Ltd <support%precedence.co.uk@localhost>
@@ -60,7 +60,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: hdafg.c,v 1.21 2020/02/15 03:04:45 isaki Exp $");
+__KERNEL_RCSID(0, "$NetBSD: hdafg.c,v 1.22 2020/04/19 04:13:09 isaki Exp $");
 
 #include <sys/types.h>
 #include <sys/param.h>
@@ -3942,12 +3942,28 @@
        return 0;
 }
 
+/* LCM for round_blocksize */
+static u_int gcd(u_int, u_int);
+static u_int lcm(u_int, u_int);
+
+static u_int gcd(u_int a, u_int b)
+{
+
+       return (b == 0) ? a : gcd(b, a % b);
+}
+static u_int lcm(u_int a, u_int b)
+{
+
+       return a * b / gcd(a, b);
+}
+
 static int
 hdafg_round_blocksize(void *opaque, int blksize, int mode,
     const audio_params_t *param)
 {
        struct hdaudio_audiodev *ad = opaque;
        struct hdaudio_stream *st;
+       u_int minblksize;
        int bufsize;
 
        st = (mode == AUMODE_PLAY) ? ad->ad_playback : ad->ad_capture;
@@ -3957,6 +3973,15 @@
                return 128;
        }
 
+       if (blksize > 8192)
+               blksize = 8192;
+
+       /* Make sure there are enough BDL descriptors */
+       bufsize = st->st_data.dma_size;
+       if (bufsize > HDAUDIO_BDL_MAX * blksize) {
+               blksize = bufsize / HDAUDIO_BDL_MAX;
+       }
+
        /*
         * HD audio's buffer constraint looks like following:
         * - The buffer MUST start on a 128bytes boundary.
@@ -3964,13 +3989,15 @@
         * - The buffer size is preferred multiple of 128bytes for efficiency.
         *
         * https://www.intel.co.jp/content/www/jp/ja/standards/high-definition-audio-specification.html , p70.
+        *
+        * Also, the audio layer requires that the blocksize must be a
+        * multiple of the number of channels.
         */
-
-       /* Make sure there are enough BDL descriptors */
-       bufsize = st->st_data.dma_size;
-       if (bufsize > HDAUDIO_BDL_MAX * blksize) {
-               blksize = bufsize / HDAUDIO_BDL_MAX;
-       }
+       minblksize = lcm(128, param->channels);
+       blksize = rounddown(blksize, minblksize);
+       if (blksize < minblksize)
+               blksize = minblksize;
+
        return blksize;
 }