From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Mon, 22 Sep 2014 21:45:40 +0200 Subject: [PATCH] mfd: inherit coherent_dma_mask from parent device In-Reply-To: <1411414675-19010-1-git-send-email-boris.brezillon@free-electrons.com> References: <1411414675-19010-1-git-send-email-boris.brezillon@free-electrons.com> Message-ID: <12718317.Y05azLtl8v@wuerfel> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 > --- > > 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