[PATCH v2 08/27] i2c: busses: remove memset after dmam_alloc_coherent

[PATCH v2 08/27] i2c: busses: remove memset after dmam_alloc_coherent

[Fuqian Huang]

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

Signed-off-by: Fuqian Huang <huangfq.daxian@gmail.com>
---
 drivers/i2c/busses/i2c-ismt.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-ismt.c b/drivers/i2c/busses/i2c-ismt.c
index 02d23edb2fb1..2f95e25a10f7 100644
--- a/drivers/i2c/busses/i2c-ismt.c
+++ b/drivers/i2c/busses/i2c-ismt.c
@@ -781,8 +781,6 @@ static int ismt_dev_init(struct ismt_priv *priv)
 	if (!priv->hw)
 		return -ENOMEM;
 
-	memset(priv->hw, 0, (ISMT_DESC_ENTRIES * sizeof(struct ismt_desc)));
-
 	priv->head = 0;
 	init_completion(&priv->cmp);
 
-- 
2.11.0

[PATCH v2 08/27] i2c: busses: remove memset after dmam_alloc_coherent

[Fuqian Huang]

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

Signed-off-by: Fuqian Huang <huangfq.daxian@gmail.com>
---
 drivers/i2c/busses/i2c-ismt.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-ismt.c b/drivers/i2c/busses/i2c-ismt.c
index 02d23edb2fb1..2f95e25a10f7 100644
--- a/drivers/i2c/busses/i2c-ismt.c
+++ b/drivers/i2c/busses/i2c-ismt.c
@@ -781,8 +781,6 @@ static int ismt_dev_init(struct ismt_priv *priv)
 	if (!priv->hw)
 		return -ENOMEM;
 
-	memset(priv->hw, 0, (ISMT_DESC_ENTRIES * sizeof(struct ismt_desc)));
-
 	priv->head = 0;
 	init_completion(&priv->cmp);
 
-- 
2.11.0

Re: [PATCH v2 08/27] i2c: busses: remove memset after dmam_alloc_coherent

[Jarkko Nikula]

Hi

On 6/28/19 5:47 AM, Fuqian Huang wrote:
> In commit af7ddd8a627c
> ("Merge tag 'dma-mapping-4.21' of git://git.infradead.org/users/hch/dma-mapping"),
> dmam_alloc_coherent has already zeroed the memory.
> So memset is not needed.
> 
> Signed-off-by: Fuqian Huang <huangfq.daxian@gmail.com>
> ---
>   drivers/i2c/busses/i2c-ismt.c | 2 --
>   1 file changed, 2 deletions(-)
> 
It would be better to refer actual commit or commits that implement that 
zeroing rather than merge point in commit log if possible.

At quick look commit 518a2f1925c3 ("dma-mapping: zero memory returned 
from dma_alloc_*") is the one but I'm not really an expert here to say 
is that alone enough.

-- 
Jarkko

Re: [PATCH v2 08/27] i2c: busses: remove memset after dmam_alloc_coherent

[Wolfram Sang]

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On Fri, Jun 28, 2019 at 09:22:31AM +0300, Jarkko Nikula wrote:
> Hi
> 
> On 6/28/19 5:47 AM, Fuqian Huang wrote:
> > In commit af7ddd8a627c
> > ("Merge tag 'dma-mapping-4.21' of git://git.infradead.org/users/hch/dma-mapping"),
> > dmam_alloc_coherent has already zeroed the memory.
> > So memset is not needed.
> > 
> > Signed-off-by: Fuqian Huang <huangfq.daxian@gmail.com>
> > ---
> >   drivers/i2c/busses/i2c-ismt.c | 2 --
> >   1 file changed, 2 deletions(-)
> > 
> It would be better to refer actual commit or commits that implement that
> zeroing rather than merge point in commit log if possible.
> 
> At quick look commit 518a2f1925c3 ("dma-mapping: zero memory returned from
> dma_alloc_*") is the one but I'm not really an expert here to say is that
> alone enough.

Fuqian, can you clarify if the commit pointed by Jarkko is enough as a
reference or if it really needs the merge tag?

Also, please include the tags you collected in v1 when sending v2 (and
there was no significant code change).


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