ALSA: memalloc: Use proper DMA mapping API for x86 WC buffer allocations

The x86 WC page allocation assumes incorrectly the DMA address
directly taken from the page.  Also it checks the DMA ops
inappropriately for switching to the own method.

This patch rewrites the stuff to use the proper DMA mapping API
instead.

Link: https://patch.msgid.link/20240912155227.4078-2-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/memalloc.c

@@ -496,41 +496,54 @@ static const struct snd_malloc_ops snd_dma_dev_ops = {
 /*
  * Write-combined pages
  */
-/* x86-specific allocations */
 #ifdef CONFIG_SND_DMA_SGBUF
-#define x86_fallback(dmab)	(!get_dma_ops(dmab->dev.dev))
-#else
-#define x86_fallback(dmab)	false
-#endif
+/* x86-specific allocations */
+static void *snd_dma_wc_alloc(struct snd_dma_buffer *dmab, size_t size)
+{
+	void *p = do_alloc_pages(dmab->dev.dev, size, &dmab->addr, true);
+
+	if (!p)
+		return NULL;
+	dmab->addr = dma_map_single(dmab->dev.dev, p, size, DMA_BIDIRECTIONAL);
+	if (dmab->addr == DMA_MAPPING_ERROR) {
+		do_free_pages(dmab->area, size, true);
+		return NULL;
+	}
+	return p;
+}
+
+static void snd_dma_wc_free(struct snd_dma_buffer *dmab)
+{
+	dma_unmap_single(dmab->dev.dev, dmab->addr, dmab->bytes,
+			 DMA_BIDIRECTIONAL);
+	do_free_pages(dmab->area, dmab->bytes, true);
+}
 
+static int snd_dma_wc_mmap(struct snd_dma_buffer *dmab,
+			   struct vm_area_struct *area)
+{
+	area->vm_page_prot = pgprot_writecombine(area->vm_page_prot);
+	return dma_mmap_coherent(dmab->dev.dev, area,
+				 dmab->area, dmab->addr, dmab->bytes);
+}
+#else
 static void *snd_dma_wc_alloc(struct snd_dma_buffer *dmab, size_t size)
 {
-	if (x86_fallback(dmab))
-		return do_alloc_pages(dmab->dev.dev, size, &dmab->addr, true);
 	return dma_alloc_wc(dmab->dev.dev, size, &dmab->addr, DEFAULT_GFP);
 }
 
 static void snd_dma_wc_free(struct snd_dma_buffer *dmab)
 {
-	if (x86_fallback(dmab)) {
-		do_free_pages(dmab->area, dmab->bytes, true);
-		return;
-	}
 	dma_free_wc(dmab->dev.dev, dmab->bytes, dmab->area, dmab->addr);
 }
 
 static int snd_dma_wc_mmap(struct snd_dma_buffer *dmab,
 			   struct vm_area_struct *area)
 {
-#ifdef CONFIG_SND_DMA_SGBUF
-	if (x86_fallback(dmab)) {
-		area->vm_page_prot = pgprot_writecombine(area->vm_page_prot);
-		return snd_dma_continuous_mmap(dmab, area);
-	}
-#endif
 	return dma_mmap_wc(dmab->dev.dev, area,
 			   dmab->area, dmab->addr, dmab->bytes);
 }
+#endif
 
 static const struct snd_malloc_ops snd_dma_wc_ops = {
 	.alloc = snd_dma_wc_alloc,
@@ -804,7 +817,7 @@ static void *snd_dma_sg_alloc(struct snd_dma_buffer *dmab, size_t size)
 
 	dmab->dev.type = type; /* restore the type */
 	/* if IOMMU is present but failed, give up */
-	if (!x86_fallback(dmab))
+	if (get_dma_ops(dmab->dev.dev))
 		return NULL;
 	/* try fallback */
 	return snd_dma_sg_fallback_alloc(dmab, size);