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authorLinus Torvalds <torvalds@linux-foundation.org>2010-05-20 12:41:44 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2010-05-20 12:41:44 -0400
commit7f06a8b26aba1dc03b42272dc0089a800372c575 (patch)
tree7c67198f83d069eb13fd417e022d111b7e4c82a1 /Documentation/DocBook
parentc3ad33c9bcb6616999953af76f16318120fe3691 (diff)
parentd71f4cece4bd97d05592836202fc04ff2e7817e3 (diff)
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6: (250 commits) ALSA: hda: Storage class should be before const qualifier ASoC: tpa6130a2: Remove CPVSS and HPVdd supplies ASoC: tpa6130a2: Define output pins with SND_SOC_DAPM_OUTPUT ASoC: sdp4430 - add sdp4430 pcm ops to DAI. ASoC: TWL6040: Enable earphone path in codec ASoC: SDP4430: Add support for Earphone speaker ASoC: SDP4430: Add sdp4430 machine driver ASoC: tlv320dac33: Avoid powering off while in BIAS_OFF ASoC: tlv320dac33: Use dev_dbg in dac33_hard_power function ALSA: sound/pci/asihpi: Use kzalloc ALSA: hdmi - dont fail on extra nodes ALSA: intelhdmi - add id for the CougarPoint chipset ALSA: intelhdmi - user friendly codec name ALSA: intelhdmi - add dependency on SND_DYNAMIC_MINORS ALSA: asihpi: incorrect range check ALSA: asihpi: testing the wrong variable ALSA: es1688: add pedantic range checks ARM: McBSP: Add support for omap4 in McBSP driver ARM: McBSP: Fix request for irq in OMAP4 OMAP: McBSP: Add 32-bit mode support ...
Diffstat (limited to 'Documentation/DocBook')
-rw-r--r--Documentation/DocBook/writing-an-alsa-driver.tmpl27
1 files changed, 17 insertions, 10 deletions
diff --git a/Documentation/DocBook/writing-an-alsa-driver.tmpl b/Documentation/DocBook/writing-an-alsa-driver.tmpl
index 0d0f7b4d4b1..0ba149de260 100644
--- a/Documentation/DocBook/writing-an-alsa-driver.tmpl
+++ b/Documentation/DocBook/writing-an-alsa-driver.tmpl
@@ -5518,34 +5518,41 @@ struct _snd_pcm_runtime {
5518]]> 5518]]>
5519 </programlisting> 5519 </programlisting>
5520 </informalexample> 5520 </informalexample>
5521
5522 For the raw data, <structfield>size</structfield> field must be
5523 set properly. This specifies the maximum size of the proc file access.
5521 </para> 5524 </para>
5522 5525
5523 <para> 5526 <para>
5524 The callback is much more complicated than the text-file 5527 The read/write callbacks of raw mode are more direct than the text mode.
5525 version. You need to use a low-level I/O functions such as 5528 You need to use a low-level I/O functions such as
5526 <function>copy_from/to_user()</function> to transfer the 5529 <function>copy_from/to_user()</function> to transfer the
5527 data. 5530 data.
5528 5531
5529 <informalexample> 5532 <informalexample>
5530 <programlisting> 5533 <programlisting>
5531<![CDATA[ 5534<![CDATA[
5532 static long my_file_io_read(struct snd_info_entry *entry, 5535 static ssize_t my_file_io_read(struct snd_info_entry *entry,
5533 void *file_private_data, 5536 void *file_private_data,
5534 struct file *file, 5537 struct file *file,
5535 char *buf, 5538 char *buf,
5536 unsigned long count, 5539 size_t count,
5537 unsigned long pos) 5540 loff_t pos)
5538 { 5541 {
5539 long size = count; 5542 if (copy_to_user(buf, local_data + pos, count))
5540 if (pos + size > local_max_size)
5541 size = local_max_size - pos;
5542 if (copy_to_user(buf, local_data + pos, size))
5543 return -EFAULT; 5543 return -EFAULT;
5544 return size; 5544 return count;
5545 } 5545 }
5546]]> 5546]]>
5547 </programlisting> 5547 </programlisting>
5548 </informalexample> 5548 </informalexample>
5549
5550 If the size of the info entry has been set up properly,
5551 <structfield>count</structfield> and <structfield>pos</structfield> are
5552 guaranteed to fit within 0 and the given size.
5553 You don't have to check the range in the callbacks unless any
5554 other condition is required.
5555
5549 </para> 5556 </para>
5550 5557
5551 </chapter> 5558 </chapter>