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authorLinus Torvalds <torvalds@linux-foundation.org>2010-05-20 09:41:44 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-05-20 09:41:44 -0700
commit7f06a8b26aba1dc03b42272dc0089a800372c575 (patch)
tree7c67198f83d069eb13fd417e022d111b7e4c82a1 /Documentation/DocBook
parentc3ad33c9bcb6616999953af76f16318120fe3691 (diff)
parentd71f4cece4bd97d05592836202fc04ff2e7817e3 (diff)
downloadlinux-linaro-android-7f06a8b26aba1dc03b42272dc0089a800372c575.tar.gz
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 {
]]>
</programlisting>
</informalexample>
+
+ For the raw data, <structfield>size</structfield> field must be
+ set properly. This specifies the maximum size of the proc file access.
</para>
<para>
- The callback is much more complicated than the text-file
- version. You need to use a low-level I/O functions such as
+ The read/write callbacks of raw mode are more direct than the text mode.
+ You need to use a low-level I/O functions such as
<function>copy_from/to_user()</function> to transfer the
data.
<informalexample>
<programlisting>
<![CDATA[
- static long my_file_io_read(struct snd_info_entry *entry,
+ static ssize_t my_file_io_read(struct snd_info_entry *entry,
void *file_private_data,
struct file *file,
char *buf,
- unsigned long count,
- unsigned long pos)
+ size_t count,
+ loff_t pos)
{
- long size = count;
- if (pos + size > local_max_size)
- size = local_max_size - pos;
- if (copy_to_user(buf, local_data + pos, size))
+ if (copy_to_user(buf, local_data + pos, count))
return -EFAULT;
- return size;
+ return count;
}
]]>
</programlisting>
</informalexample>
+
+ If the size of the info entry has been set up properly,
+ <structfield>count</structfield> and <structfield>pos</structfield> are
+ guaranteed to fit within 0 and the given size.
+ You don't have to check the range in the callbacks unless any
+ other condition is required.
+
</para>
</chapter>