Le 28/06/2019 à 11:11, Fuqian Huang a écrit :

The merge commit log tells (dma-mapping: zero memory returned from
dma_alloc_* and deprecating the dma_zalloc_coherent).
I used this commit just want to say that dma_alloc_coherent  has
zeroed the allocated memory.
Sorry for this mistake.

Maybe this commit 518a2f1925c3("dma-mapping: zero memory returned from
dma_alloc_*") is correct.

Yes that looks appropriate. And it confirms it was already done on 
powerpc, as that patch doesn't include any change in powerpc arch.

Christophe

Christophe Leroy [off-list ref] 於 2019年6月28日週五 下午4:59寫道：

quoted

Le 28/06/2019 à 04:50, Fuqian Huang a écrit :

quoted

In commit af7ddd8a627c
("Merge tag 'dma-mapping-4.21' of git://git.infradead.org/users/hch/dma-mapping"),
dma_alloc_coherent has already zeroed the memory.
So memset is not needed.

You are refering to a merge commit, is that correct ?

I can't see anything related in that commit, can you please pinpoint it ?

As far as I can see, on powerpc the memory has always been zeroized
(since 2005 at least).

Christophe

quoted

Signed-off-by: Fuqian Huang <redacted>
---
   sound/ppc/pmac.c | 1 -
   1 file changed, 1 deletion(-)

diff --git a/sound/ppc/pmac.c b/sound/ppc/pmac.c
index 1b11e53f6a62..1ab12f4f8631 100644
--- a/sound/ppc/pmac.c
+++ b/sound/ppc/pmac.c

@@ -56,7 +56,6 @@ static int snd_pmac_dbdma_alloc(struct snd_pmac *chip, struct pmac_dbdma *rec, i
       if (rec->space == NULL)
               return -ENOMEM;
       rec->size = size;
-     memset(rec->space, 0, rsize);
       rec->cmds = (void __iomem *)DBDMA_ALIGN(rec->space);
       rec->addr = rec->dma_base + (unsigned long)((char *)rec->cmds - (char *)rec->space);