[alsa-devel] 答复: A bug about cache inconsistency report

[Takashi Iwai]

On Thu, 02 Aug 2018 12:56:30 +0200,
Hans Hu(SH-RD) wrote:
> 
> 1. noise relate test:
> When I annotate the return after set_pages_array_wc, then set_memory_wc works, noise disappear
> static void __mark_pages_wc(struct azx *chip, struct snd_dma_buffer *dmab, bool on)
> {
> ...
> set_pages_array_wb(sgbuf->page_table, sgbuf->pages);
> //return;
> }
> #endif

set_memory_uc() performs __pa() for the given address, and in this
case, it's vmapped address.  Something bogus in your test, I'm
afraid.

And moreover, all Intel chipsets do work with snooping well, AFAIK.


> }
> 
> 2. change *_SG relate test:
> Just followed your proposal
> -snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV_SG,
> +snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV,

OK, you need one more oneliner:

diff --git a/sound/pci/hda/hda_controller.c b/sound/pci/hda/hda_controller.c
index a12e594d4e3b..2eaed4956e7f 100644
--- a/sound/pci/hda/hda_controller.c
+++ b/sound/pci/hda/hda_controller.c
@@ -707,7 +707,7 @@ static const struct snd_pcm_ops azx_pcm_ops = {
 	.pointer = azx_pcm_pointer,
 	.get_time_info =  azx_get_time_info,
 	.mmap = azx_pcm_mmap,
-	.page = snd_pcm_sgbuf_ops_page,
+	// .page = snd_pcm_sgbuf_ops_page,
 };
 
 static void azx_pcm_free(struct snd_pcm *pcm)


And, again, please avoid top-posting.


Takashi