[ALSA] Add write support to snd-page-alloc proc file
Documentation,Memalloc module,RME HDSP driver,RME9652 driver
Add the write support to snd-page-alloc proc file for buffer pre-allocation.
Removed the pre-allocation codes via module options.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt
index 2260130..812ed2b 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -671,7 +671,8 @@
module did formerly. It will allocate the buffers in advance
when any HDSP cards are found. To make the buffer
allocation sure, load snd-page-alloc module in the early
- stage of boot sequence.
+ stage of boot sequence. See "Early Buffer Allocation"
+ section.
Module snd-ice1712
------------------
@@ -1067,7 +1068,8 @@
module did formerly. It will allocate the buffers in advance
when any RME9652 cards are found. To make the buffer
allocation sure, load snd-page-alloc module in the early
- stage of boot sequence.
+ stage of boot sequence. See "Early Buffer Allocation"
+ section.
Module snd-sa11xx-uda1341 (on arm only)
---------------------------------------
@@ -1545,6 +1547,36 @@
echo "rvplayer 0 0 block" > /proc/asound/card0/pcm0p/oss
+Early Buffer Allocation
+=======================
+
+Some drivers (e.g. hdsp) require the large contiguous buffers, and
+sometimes it's too late to find such spaces when the driver module is
+actually loaded due to memory fragmentation. You can pre-allocate the
+PCM buffers by loading snd-page-alloc module and write commands to its
+proc file in prior, for example, in the early boot stage like
+/etc/init.d/*.local scripts.
+
+Reading the proc file /proc/drivers/snd-page-alloc shows the current
+usage of page allocation. In writing, you can send the following
+commands to the snd-page-alloc driver:
+
+ - add VENDOR DEVICE MASK SIZE BUFFERS
+
+ VENDOR and DEVICE are PCI vendor and device IDs. They take
+ integer numbers (0x prefix is needed for the hex).
+ MASK is the PCI DMA mask. Pass 0 if not restricted.
+ SIZE is the size of each buffer to allocate. You can pass
+ k and m suffix for KB and MB. The max number is 16MB.
+ BUFFERS is the number of buffers to allocate. It must be greater
+ than 0. The max number is 4.
+
+ - erase
+
+ This will erase the all pre-allocated buffers which are not in
+ use.
+
+
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