At Tue, 9 Mar 2010 12:57:52 -0500, Mike Frysinger wrote:
From: Daniel Glöckner dg@emlix.com
Shared memory mappings on nommu machines require a get_unmapped_area file operation that suggests an address for the mapping. The current implementation returns 0 and thus forces the driver to implement an mmap handler that fixes up the start and end address of the vma.
This patch returns the address of the dma buffer, so it should work out of the box for all drivers that use the snd_pcm_runtime->dma_area pointer.
Addresses for mapping the status and control pages are returned as well, but to make those work the conditional compilation of snd_pcm_mmap_{status,control} would need to be revised.
URL: http://thread.gmane.org/gmane.linux.alsa.devel/61230 Signed-off-by: Daniel Glöckner dg@emlix.com Signed-off-by: Cliff Cai cliff.cai@analog.com Signed-off-by: Mike Frysinger vapier@gentoo.org
this has been posted before but didnt seem to get any feedback ...
Looks so. Now I applied the patch. I'll add it for 2.6.34 merge, too.
This doesn't work for every case, though. But the irregular cases without dma_area setup don't provide mmap usually, so mostly OK :)
thanks,
Takashi
sound/core/pcm_native.c | 30 ++++++++++++++++++++++-------- 1 files changed, 22 insertions(+), 8 deletions(-)
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index 8728876..9681518 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -3434,14 +3434,28 @@ out: #endif /* CONFIG_SND_SUPPORT_OLD_API */
#ifndef CONFIG_MMU -unsigned long dummy_get_unmapped_area(struct file *file, unsigned long addr,
unsigned long len, unsigned long pgoff,unsigned long flags)-{
- return 0;
+static unsigned long snd_pcm_get_unmapped_area(struct file *file,
unsigned long addr,unsigned long len,unsigned long pgoff,unsigned long flags)+{
- struct snd_pcm_file *pcm_file = file->private_data;
- struct snd_pcm_substream *substream = pcm_file->substream;
- struct snd_pcm_runtime *runtime = substream->runtime;
- unsigned long offset = pgoff << PAGE_SHIFT;
- switch (offset) {
- case SNDRV_PCM_MMAP_OFFSET_STATUS:
return (unsigned long)runtime->status;- case SNDRV_PCM_MMAP_OFFSET_CONTROL:
return (unsigned long)runtime->control;- default:
return (unsigned long)runtime->dma_area + offset;- }
} #else -# define dummy_get_unmapped_area NULL +# define snd_pcm_get_unmapped_area NULL #endif
/* @@ -3460,7 +3474,7 @@ const struct file_operations snd_pcm_f_ops[2] = { .compat_ioctl = snd_pcm_ioctl_compat, .mmap = snd_pcm_mmap, .fasync = snd_pcm_fasync,
.get_unmapped_area = dummy_get_unmapped_area,
.get_unmapped_area = snd_pcm_get_unmapped_area,@@ -3473,6 +3487,6 @@ const struct file_operations snd_pcm_f_ops[2] = { .compat_ioctl = snd_pcm_ioctl_compat, .mmap = snd_pcm_mmap, .fasync = snd_pcm_fasync,
.get_unmapped_area = dummy_get_unmapped_area,
.get_unmapped_area = snd_pcm_get_unmapped_area,};
1.7.0.2