From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Fuqian Huang <huangfq.daxian@gmail.com>
Cc: Rob Herring <robh@kernel.org>,
alsa-devel@alsa-project.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org, Jaroslav Kysela <perex@perex.cz>,
Richard Fontana <rfontana@redhat.com>,
Paul Mackerras <paulus@samba.org>,
Thomas Gleixner <tglx@linutronix.de>,
linuxppc-dev@lists.ozlabs.org,
Allison Randal <allison@lohutok.net>
Subject: Re: [PATCH v2 27/27] sound: ppc: remove unneeded memset after dma_alloc_coherent
Date: Fri, 28 Jun 2019 11:48:37 +0200 [thread overview]
Message-ID: <ae51454e-68b1-bc82-8d8f-dbc273166dc3@c-s.fr> (raw)
In-Reply-To: <CABXRUiT6jSP2xL9JyqngS9KBx_=fZ13x0UGGFPnQPrfh-_N5xQ@mail.gmail.com>
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 <christophe.leroy@c-s.fr> 於 2019年6月28日週五 下午4:59寫道:
>
>>
>>
>>
>> Le 28/06/2019 à 04:50, Fuqian Huang a écrit :
>>> 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
>>
>>>
>>> Signed-off-by: Fuqian Huang <huangfq.daxian@gmail.com>
>>> ---
>>> 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);
>>>
>>>
prev parent reply other threads:[~2019-06-28 9:50 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-28 2:50 [PATCH v2 27/27] sound: ppc: remove unneeded memset after dma_alloc_coherent Fuqian Huang
2019-06-28 8:59 ` Christophe Leroy
2019-06-28 9:11 ` Fuqian Huang
2019-06-28 9:17 ` [alsa-devel] " Takashi Iwai
2019-06-28 9:48 ` Christophe Leroy [this message]
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