From: Arnd Bergmann <arnd@arndb.de>
To: Boris BREZILLON <boris.brezillon@free-electrons.com>
Cc: Samuel Ortiz <sameo@linux.intel.com>,
Lee Jones <lee.jones@linaro.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mfd: inherit coherent_dma_mask from parent device
Date: Mon, 22 Sep 2014 21:45:40 +0200 [thread overview]
Message-ID: <12718317.Y05azLtl8v@wuerfel> (raw)
In-Reply-To: <1411414675-19010-1-git-send-email-boris.brezillon@free-electrons.com>
On Monday 22 September 2014 21:37:55 Boris BREZILLON wrote:
> dma_mask and dma_parms are already inherited from the parent device but
> dma_coherent_mask was left uninitialized (set to zero thanks to kzalloc).
> Set sub-device coherent_dma_mask to its parent value to simplify
> sub-drivers making use of dma coherent helper functions (those drivers
> currently have to explicitly set the dma coherent mask using
> dma_set_coherent_mask function).
>
> Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
> ---
>
> Hi,
>
> This patch is follow-up of a discussion we had on a KMS driver thread [1].
> This patch is only copying the parent device coherent_dma_mask to avoid
> calling specific dma_set_coherent_mask in case the coherent mask is the
> default one.
>
> I'm a bit surprised this hasn't been done earlier while other dma fields
> (mask and parms) are already inherited from the parent device, so please
> tell me if there already was an attempt to do the same, and if so, what
> was the reson for rejecting it :-).
>
>
Seems reasonable to me. It's not clear whether we should always inherit
the dma_mask, but I see no point in copying just dma_mask but not
coherent_dma_mask.
Acked-by: Arnd Bergmann <arnd@arndb.de>
next prev parent reply other threads:[~2014-09-22 19:46 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-22 19:37 [PATCH] mfd: inherit coherent_dma_mask from parent device Boris BREZILLON
2014-09-22 19:45 ` Arnd Bergmann [this message]
2014-09-23 5:13 ` Boris BREZILLON
2014-09-24 10:14 ` Lee Jones
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