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-rw-r--r--Documentation/sound/alsa/ALSA-Configuration.txt36
1 files changed, 34 insertions, 2 deletions
diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt
index 226013035d72..812ed2b80b8d 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -671,7 +671,8 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
671 module did formerly. It will allocate the buffers in advance 671 module did formerly. It will allocate the buffers in advance
672 when any HDSP cards are found. To make the buffer 672 when any HDSP cards are found. To make the buffer
673 allocation sure, load snd-page-alloc module in the early 673 allocation sure, load snd-page-alloc module in the early
674 stage of boot sequence. 674 stage of boot sequence. See "Early Buffer Allocation"
675 section.
675 676
676 Module snd-ice1712 677 Module snd-ice1712
677 ------------------ 678 ------------------
@@ -1067,7 +1068,8 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
1067 module did formerly. It will allocate the buffers in advance 1068 module did formerly. It will allocate the buffers in advance
1068 when any RME9652 cards are found. To make the buffer 1069 when any RME9652 cards are found. To make the buffer
1069 allocation sure, load snd-page-alloc module in the early 1070 allocation sure, load snd-page-alloc module in the early
1070 stage of boot sequence. 1071 stage of boot sequence. See "Early Buffer Allocation"
1072 section.
1071 1073
1072 Module snd-sa11xx-uda1341 (on arm only) 1074 Module snd-sa11xx-uda1341 (on arm only)
1073 --------------------------------------- 1075 ---------------------------------------
@@ -1545,6 +1547,36 @@ Proc interfaces (/proc/asound)
1545 echo "rvplayer 0 0 block" > /proc/asound/card0/pcm0p/oss 1547 echo "rvplayer 0 0 block" > /proc/asound/card0/pcm0p/oss
1546 1548
1547 1549
1550Early Buffer Allocation
1551=======================
1552
1553Some drivers (e.g. hdsp) require the large contiguous buffers, and
1554sometimes it's too late to find such spaces when the driver module is
1555actually loaded due to memory fragmentation. You can pre-allocate the
1556PCM buffers by loading snd-page-alloc module and write commands to its
1557proc file in prior, for example, in the early boot stage like
1558/etc/init.d/*.local scripts.
1559
1560Reading the proc file /proc/drivers/snd-page-alloc shows the current
1561usage of page allocation. In writing, you can send the following
1562commands to the snd-page-alloc driver:
1563
1564 - add VENDOR DEVICE MASK SIZE BUFFERS
1565
1566 VENDOR and DEVICE are PCI vendor and device IDs. They take
1567 integer numbers (0x prefix is needed for the hex).
1568 MASK is the PCI DMA mask. Pass 0 if not restricted.
1569 SIZE is the size of each buffer to allocate. You can pass
1570 k and m suffix for KB and MB. The max number is 16MB.
1571 BUFFERS is the number of buffers to allocate. It must be greater
1572 than 0. The max number is 4.
1573
1574 - erase
1575
1576 This will erase the all pre-allocated buffers which are not in
1577 use.
1578
1579
1548Links 1580Links
1549===== 1581=====
1550 1582