From mboxrd@z Thu Jan 1 00:00:00 1970 From: viresh.kumar@st.com (viresh kumar) Date: Wed, 10 Aug 2011 14:59:31 +0530 Subject: [PATCH V2 6/6] spi/spi-pl022: Request/free DMA channels as and when required. In-Reply-To: <20110810090042.GE1831@n2100.arm.linux.org.uk> References: <566c0525199f498f04422d4c3b2ddd7466648c20.1312965742.git.viresh.kumar@st.com> <20110810090042.GE1831@n2100.arm.linux.org.uk> Message-ID: <4E424F7B.2000800@st.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 08/10/2011 02:30 PM, Russell King - ARM Linux wrote: >> > They must be allocated when they are required and must be freed after we are >> > done with transfers. So that they can be used by other users. > Which DMA engine driver requires this? > dw_dmac.c > Normally, when we have DMA engine drivers with multiple request signals, > the slave peripheral side publishes several virtual channels which are > claimed by the peripheral drivers. This (amongst other things) allows > the peripheral drivers to hold claim to one of the virtual channels > all the time that it's required. If users of DMA expect DMA engine drivers to work this way, then we should have this mentioned clearly in DMA slave documentation. @Dan/Vinod: What do you say? -- viresh