vaddr = runtime->dma_area + offset;
+#if defined(__mips__) && defined(CONFIG_DMA_NONCOHERENT)
Please use CONFIG_MIPS instead of __mips__ in #if / #ifdefs.
The question if #ifdefing is the right approach to solve this problem is
something else but I think no, ....
I would agree that it is quite ugly, but changing virt_to_page for it
does not seem right either.
+ page = virt_to_page(CAC_ADDR(vaddr));
+#else
page = virt_to_page(vaddr);
+#endif
So this is needed because the MIPS virt_to_page is returning a unsuitable
value if vaddress is not a KSEG0 (64-bit: cached XKPHYS) address which is
what GFP allocations and the slab will return. So now we have to deciede
if
a) the MIPS __pa() should be changed to handle uncached addresses.
b) the sound code here is simply broken.
Some drivers seem to allocate runtime->dma_area from vmalloc, so this
whole area in the sound code is looking like built on quicksand ...
+#if defined(__mips__) && defined(CONFIG_DMA_NONCOHERENT)
+ /* all mmap using uncached mode */
+ area->vm_page_prot = pgprot_noncached(area->vm_page_prot);
+ area->vm_flags |= ( VM_RESERVED | VM_IO);
VM_RESERVED will prevent the buffer from being freed. I assume that is
another workaround for some kernel subsystem blowing up when being fed a
pointer to an uncached RAM address? This smells like a memory leak.
Oh, VM_RESERVED should be a memory leak problem, we can remove it.
I don't remember any case of other subsystem's problem, just did not
think much
to add those flags.
+#endif
+
offset = area->vm_pgoff << PAGE_SHIFT;
switch (offset) {
case SNDRV_PCM_MMAP_OFFSET_STATUS:
diff --git a/sound/core/sgbuf.c b/sound/core/sgbuf.c
index cefd228..535f0bc 100644
--- a/sound/core/sgbuf.c
+++ b/sound/core/sgbuf.c
@@ -91,12 +91,21 @@ void *snd_malloc_sgbuf_pages(struct device *device,
}
sgbuf->table[i].buf = tmpb.area;
sgbuf->table[i].addr = tmpb.addr;
+#if defined(__mips__) && defined(CONFIG_DMA_NONCOHERENT)
+ sgbuf->page_table[i] = virt_to_page(CAC_ADDR(tmpb.area));
VM_RESERVED will prevent the buffer from being freed. I assume that is
another workaround for some kernel subsystem blowing up when being fed a
pointer to an uncached RAM address? This smells like a memory leak.
+#else
sgbuf->page_table[i] = virt_to_page(tmpb.area);
+#endif
sgbuf->pages++;
}
sgbuf->size = size;
+#if defined(__mips__) && defined(CONFIG_DMA_NONCOHERENT)
+ /* maybe we should use uncached accelerated mode */
+ dmab->area = vmap(sgbuf->page_table, sgbuf->pages, VM_MAP | VM_IO, pgprot_noncached(PAGE_KERNEL));
+#else
dmab->area = vmap(sgbuf->page_table, sgbuf->pages, VM_MAP, PAGE_KERNEL);
+#endif
I would suggest to get rid of this ifdef with a new arch-specific function
like vmap_io_buffer which will do whatever a platform seems fit for this
case?
I think arch-specific function is the correct way, but don't know what
the alsa gods think.
if (! dmab->area)
goto _failed;
return dmab->area;
Ralf
