From: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org> To: Vinod Koul <vinod.koul-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> Cc: Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>, device-tree <devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org>, Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>, Jassi Brar <jaswinder.singh-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, Russell King - ARM Linux <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>, dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, linux-omap <linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org Subject: Re: [PATCH V3 1/2] of: Add generic device tree DMA helpers Date: Thu, 26 Jul 2012 07:14:34 +0000 [thread overview] Message-ID: <201207260714.34540.arnd@arndb.de> (raw) In-Reply-To: <1343284960.1726.8978.camel@vkoul-udesk3> On Thursday 26 July 2012, Vinod Koul wrote: > > > But from a client POV it makes sense as with the given direction you > > > would need a specific request line for a channel. So this is right. > > > But direction is something I don't expect to be used for "give me a > > > channel" > > > > Ok. The thought was that the user would have the following means of > > requesting a channel ... > > > > 1. By name > Bare name maynot be enough. In a dmac we have many channels which one to > choose? The name is what is associated with the property in the client device node, which describes everything the dmac driver needs to know. If the dmac needs to pick a specific channel, it can find out from the "dmas" property in combination with that name. If it is allowed to pick any channel, it doesn't need to bother. > > 2. By a filter parameter (flags) > Even with direction same problem can arise Again this is just identifying which dma specifier from the "dmas" property to pick. The use case is the very common one that there is at most one "read" and one "write" channel. In this case all the client has to know is that it wants a channel that fits the description given in DT for the direction it's looking for. > > 3. By name and a filter parameter > Additionally we need to say which channel, or making dmaengine already > aware will help here. The channel is still described in the specifier, the client should not care about it. Arnd
WARNING: multiple messages have this Message-ID (diff)
From: arnd@arndb.de (Arnd Bergmann) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH V3 1/2] of: Add generic device tree DMA helpers Date: Thu, 26 Jul 2012 07:14:34 +0000 [thread overview] Message-ID: <201207260714.34540.arnd@arndb.de> (raw) In-Reply-To: <1343284960.1726.8978.camel@vkoul-udesk3> On Thursday 26 July 2012, Vinod Koul wrote: > > > But from a client POV it makes sense as with the given direction you > > > would need a specific request line for a channel. So this is right. > > > But direction is something I don't expect to be used for "give me a > > > channel" > > > > Ok. The thought was that the user would have the following means of > > requesting a channel ... > > > > 1. By name > Bare name maynot be enough. In a dmac we have many channels which one to > choose? The name is what is associated with the property in the client device node, which describes everything the dmac driver needs to know. If the dmac needs to pick a specific channel, it can find out from the "dmas" property in combination with that name. If it is allowed to pick any channel, it doesn't need to bother. > > 2. By a filter parameter (flags) > Even with direction same problem can arise Again this is just identifying which dma specifier from the "dmas" property to pick. The use case is the very common one that there is at most one "read" and one "write" channel. In this case all the client has to know is that it wants a channel that fits the description given in DT for the direction it's looking for. > > 3. By name and a filter parameter > Additionally we need to say which channel, or making dmaengine already > aware will help here. The channel is still described in the specifier, the client should not care about it. Arnd
next prev parent reply other threads:[~2012-07-26 7:14 UTC|newest] Thread overview: 258+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-04-30 21:17 [PATCH V3 1/2] of: Add generic device tree DMA helpers Jon Hunter 2012-04-30 21:17 ` Jon Hunter 2012-05-03 22:26 ` Stephen Warren 2012-05-03 22:26 ` Stephen Warren [not found] ` <4FA30604.1030401-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> 2012-05-03 23:25 ` Russell King - ARM Linux 2012-05-03 23:25 ` Russell King - ARM Linux 2012-05-04 12:39 ` Arnd Bergmann 2012-05-04 12:39 ` Arnd Bergmann 2012-05-04 15:06 ` Jon Hunter 2012-05-04 15:06 ` Jon Hunter [not found] ` <4FA3F08D.7030603-l0cyMroinI0@public.gmane.org> 2012-05-04 15:14 ` Russell King - ARM Linux 2012-05-04 15:14 ` Russell King - ARM Linux 2012-05-04 18:21 ` Stephen Warren 2012-05-04 18:21 ` Stephen Warren 2012-05-04 19:19 ` Jon Hunter 2012-05-04 19:19 ` Jon Hunter 2012-05-04 6:56 ` Jassi Brar 2012-05-04 6:56 ` Jassi Brar 2012-05-04 15:17 ` Jon Hunter 2012-05-04 15:17 ` Jon Hunter 2012-05-04 19:01 ` Jassi Brar 2012-05-04 19:01 ` Jassi Brar 2012-05-04 19:23 ` Arnd Bergmann 2012-05-04 19:23 ` Arnd Bergmann 2012-05-05 17:10 ` Jassi Brar 2012-05-05 17:10 ` Jassi Brar 2012-05-07 15:53 ` Stephen Warren 2012-05-07 15:53 ` Stephen Warren 2012-05-07 17:19 ` Jassi Brar 2012-05-07 17:19 ` Jassi Brar 2012-05-08 16:35 ` Stephen Warren 2012-05-08 16:35 ` Stephen Warren 2012-05-08 19:09 ` Jassi Brar 2012-05-08 19:09 ` Jassi Brar 2012-05-09 12:30 ` Arnd Bergmann 2012-05-09 12:30 ` Arnd Bergmann 2012-05-09 19:10 ` Stephen Warren 2012-05-09 19:10 ` Stephen Warren 2012-05-09 21:38 ` Jassi Brar 2012-05-09 21:38 ` Jassi Brar 2012-05-10 17:00 ` Stephen Warren 2012-05-10 17:00 ` Stephen Warren 2012-05-10 19:59 ` Jassi Brar 2012-05-10 19:59 ` Jassi Brar 2012-05-11 19:28 ` Stephen Warren 2012-05-11 19:28 ` Stephen Warren 2012-05-11 21:06 ` Jassi Brar 2012-05-11 21:06 ` Jassi Brar 2012-05-11 23:51 ` Stephen Warren 2012-05-11 23:51 ` Stephen Warren 2012-05-12 13:40 ` Jassi Brar 2012-05-12 13:40 ` Jassi Brar 2012-05-16 1:05 ` Jon Hunter 2012-05-16 1:05 ` Jon Hunter 2012-05-17 13:18 ` Russell King - ARM Linux 2012-05-17 13:18 ` Russell King - ARM Linux 2012-05-07 17:21 ` Arnd Bergmann 2012-05-07 17:21 ` Arnd Bergmann 2012-05-16 1:11 ` Jon Hunter 2012-05-16 1:11 ` Jon Hunter 2012-05-16 12:37 ` Jassi Brar 2012-05-16 12:37 ` Jassi Brar 2012-05-16 13:15 ` Jon Hunter 2012-05-16 13:15 ` Jon Hunter 2012-05-16 15:44 ` Stephen Warren 2012-05-16 15:44 ` Stephen Warren 2012-05-16 16:04 ` Jon Hunter 2012-05-16 16:04 ` Jon Hunter 2012-05-16 16:01 ` Jon Hunter 2012-05-16 16:01 ` Jon Hunter 2012-05-16 16:15 ` Stephen Warren 2012-05-16 16:15 ` Stephen Warren 2012-05-16 16:22 ` Jassi Brar 2012-05-16 16:22 ` Jassi Brar 2012-05-16 17:09 ` Jon Hunter 2012-05-16 17:09 ` Jon Hunter 2012-05-16 19:42 ` Arnd Bergmann 2012-05-16 19:42 ` Arnd Bergmann 2012-05-16 21:16 ` Jassi Brar 2012-05-16 21:16 ` Jassi Brar 2012-05-17 19:32 ` Stephen Warren 2012-05-17 19:32 ` Stephen Warren 2012-05-18 17:12 ` Jassi Brar 2012-05-18 17:12 ` Jassi Brar 2012-05-18 21:04 ` Arnd Bergmann 2012-05-18 21:04 ` Arnd Bergmann 2012-05-16 23:59 ` Stephen Warren 2012-05-16 23:59 ` Stephen Warren 2012-05-17 4:05 ` Jassi Brar 2012-05-17 4:05 ` Jassi Brar 2012-05-18 20:49 ` Arnd Bergmann 2012-05-18 20:49 ` Arnd Bergmann 2012-05-18 21:07 ` Stephen Warren 2012-05-18 21:07 ` Stephen Warren 2012-05-18 21:43 ` Arnd Bergmann 2012-05-18 21:43 ` Arnd Bergmann 2012-05-18 22:20 ` Stephen Warren 2012-05-18 22:20 ` Stephen Warren 2012-05-19 8:44 ` Arnd Bergmann 2012-05-19 8:44 ` Arnd Bergmann 2012-05-21 17:33 ` Stephen Warren 2012-05-21 17:33 ` Stephen Warren 2012-05-21 18:18 ` Arnd Bergmann 2012-05-21 18:18 ` Arnd Bergmann 2012-05-21 20:32 ` Stephen Warren 2012-05-21 20:32 ` Stephen Warren 2012-06-08 19:04 ` Jon Hunter 2012-06-08 19:04 ` Jon Hunter 2012-06-09 0:04 ` Arnd Bergmann 2012-06-09 0:04 ` Arnd Bergmann 2012-06-13 22:32 ` Jon Hunter 2012-06-13 22:32 ` Jon Hunter 2012-06-14 4:45 ` Jassi Brar 2012-06-14 4:45 ` Jassi Brar 2012-06-14 11:48 ` Arnd Bergmann 2012-06-14 11:48 ` Arnd Bergmann 2012-06-14 15:39 ` Jon Hunter 2012-06-14 15:39 ` Jon Hunter 2012-06-15 8:40 ` Arnd Bergmann 2012-06-15 8:40 ` Arnd Bergmann 2012-06-22 22:52 ` Jon Hunter 2012-06-22 22:52 ` Jon Hunter [not found] ` <4FE4F718.3080204-l0cyMroinI0@public.gmane.org> 2012-06-22 23:12 ` Russell King - ARM Linux 2012-06-22 23:12 ` Russell King - ARM Linux 2012-06-25 16:51 ` Jon Hunter 2012-06-25 16:51 ` Jon Hunter 2012-06-25 18:04 ` Vinod Koul 2012-06-25 18:04 ` Vinod Koul 2012-06-25 20:30 ` Arnd Bergmann 2012-06-25 20:30 ` Arnd Bergmann 2012-06-26 9:40 ` Vinod Koul 2012-06-26 9:40 ` Vinod Koul 2012-06-26 14:59 ` Arnd Bergmann 2012-06-26 14:59 ` Arnd Bergmann 2012-06-26 17:50 ` Vinod Koul 2012-06-26 17:50 ` Vinod Koul 2012-06-26 20:27 ` Arnd Bergmann 2012-06-26 20:27 ` Arnd Bergmann 2012-06-27 13:45 ` Vinod Koul 2012-06-27 13:45 ` Vinod Koul 2012-06-27 15:20 ` Arnd Bergmann 2012-06-27 15:20 ` Arnd Bergmann 2012-07-13 6:45 ` Vinod Koul 2012-07-13 6:45 ` Vinod Koul 2012-07-13 21:52 ` Guennadi Liakhovetski 2012-07-13 21:52 ` Guennadi Liakhovetski 2012-07-17 19:24 ` Arnd Bergmann 2012-07-17 19:24 ` Arnd Bergmann 2012-07-20 4:00 ` Vinod Koul 2012-07-20 4:00 ` Vinod Koul 2012-07-20 8:39 ` Arnd Bergmann 2012-07-20 8:39 ` Arnd Bergmann 2012-07-20 9:37 ` Vinod Koul 2012-07-20 9:37 ` Vinod Koul 2012-07-24 19:07 ` Jon Hunter 2012-07-24 19:07 ` Jon Hunter 2012-07-24 19:27 ` Arnd Bergmann 2012-07-24 19:27 ` Arnd Bergmann 2012-07-26 6:42 ` Vinod Koul 2012-07-26 6:42 ` Vinod Koul 2012-07-26 7:14 ` Arnd Bergmann [this message] 2012-07-26 7:14 ` Arnd Bergmann 2012-07-26 11:28 ` Vinod Koul 2012-07-26 11:28 ` Vinod Koul 2012-07-26 15:53 ` Jon Hunter 2012-07-26 15:53 ` Jon Hunter [not found] ` <5011680A.6040400-l0cyMroinI0@public.gmane.org> 2012-07-31 11:06 ` Vinod Koul 2012-07-31 11:06 ` Vinod Koul 2012-07-26 17:43 ` Jon Hunter 2012-07-26 17:43 ` Jon Hunter 2012-07-31 11:12 ` Vinod Koul 2012-07-31 11:12 ` Vinod Koul 2012-08-01 20:43 ` Jon Hunter 2012-08-01 20:43 ` Jon Hunter 2012-08-03 9:55 ` Vinod Koul 2012-08-03 9:55 ` Vinod Koul 2012-07-20 9:08 ` Robert Jarzmik 2012-07-20 9:08 ` Robert Jarzmik 2012-07-20 9:41 ` Vinod Koul 2012-07-20 9:41 ` Vinod Koul 2012-07-26 4:56 ` zhangfei gao 2012-07-26 4:56 ` zhangfei gao 2012-07-23 21:29 ` Stephen Warren 2012-07-23 21:29 ` Stephen Warren 2012-07-24 7:19 ` Arnd Bergmann 2012-07-24 7:19 ` Arnd Bergmann 2012-07-24 16:04 ` Stephen Warren 2012-07-24 16:04 ` Stephen Warren 2012-07-24 18:55 ` Arnd Bergmann 2012-07-24 18:55 ` Arnd Bergmann 2012-07-24 12:54 ` Sergei Shtylyov 2012-07-24 12:54 ` Sergei Shtylyov 2012-07-06 11:36 ` Guennadi Liakhovetski 2012-07-06 11:36 ` Guennadi Liakhovetski [not found] ` <Pine.LNX.4.64.1207061315470.29809-0199iw4Nj15frtckUFj5Ag@public.gmane.org> 2012-07-06 15:28 ` Arnd Bergmann 2012-07-06 15:28 ` Arnd Bergmann [not found] ` <201207061528.58291.arnd-r2nGTMty4D4@public.gmane.org> 2012-07-06 15:43 ` Guennadi Liakhovetski 2012-07-06 15:43 ` Guennadi Liakhovetski 2012-07-06 17:31 ` Arnd Bergmann 2012-07-06 17:31 ` Arnd Bergmann 2012-07-06 21:01 ` Russell King - ARM Linux 2012-07-06 21:01 ` Russell King - ARM Linux 2012-07-06 20:57 ` Russell King - ARM Linux 2012-07-06 20:57 ` Russell King - ARM Linux 2012-07-06 22:49 ` Guennadi Liakhovetski 2012-07-06 22:49 ` Guennadi Liakhovetski 2012-07-13 6:51 ` Vinod Koul 2012-07-13 6:51 ` Vinod Koul 2012-06-14 15:17 ` Guennadi Liakhovetski 2012-06-14 15:17 ` Guennadi Liakhovetski 2012-06-14 21:52 ` Jon Hunter 2012-06-14 21:52 ` Jon Hunter 2012-06-15 8:41 ` Guennadi Liakhovetski 2012-06-15 8:41 ` Guennadi Liakhovetski 2012-06-15 9:00 ` Arnd Bergmann 2012-06-15 9:00 ` Arnd Bergmann 2012-06-15 9:18 ` Guennadi Liakhovetski 2012-06-15 9:18 ` Guennadi Liakhovetski 2012-06-15 11:27 ` Arnd Bergmann 2012-06-15 11:27 ` Arnd Bergmann [not found] ` <201206151127.24386.arnd-r2nGTMty4D4@public.gmane.org> 2012-06-15 16:11 ` Mitch Bradley 2012-06-15 16:11 ` Mitch Bradley [not found] ` <4FDB5ECF.3000701-D5eQfiDGL7eakBO8gow8eQ@public.gmane.org> 2012-06-16 6:56 ` Arnd Bergmann 2012-06-16 6:56 ` Arnd Bergmann 2012-06-21 11:21 ` Guennadi Liakhovetski 2012-06-21 11:21 ` Guennadi Liakhovetski 2012-06-21 14:56 ` Arnd Bergmann 2012-06-21 14:56 ` Arnd Bergmann [not found] ` <201205161942.20296.arnd-r2nGTMty4D4@public.gmane.org> 2012-05-17 13:22 ` Russell King - ARM Linux 2012-05-17 13:22 ` Russell King - ARM Linux 2012-05-17 13:52 ` Mark Brown 2012-05-17 13:52 ` Mark Brown 2012-05-17 14:16 ` Russell King - ARM Linux 2012-05-17 14:16 ` Russell King - ARM Linux 2012-05-16 16:16 ` Jassi Brar 2012-05-16 16:16 ` Jassi Brar 2012-05-16 17:12 ` Jon Hunter 2012-05-16 17:12 ` Jon Hunter 2012-05-16 17:24 ` Jassi Brar 2012-05-16 17:24 ` Jassi Brar 2012-05-16 17:37 ` Jon Hunter 2012-05-16 17:37 ` Jon Hunter 2012-05-16 17:46 ` Stephen Warren 2012-05-16 17:46 ` Stephen Warren 2012-05-16 18:03 ` Jon Hunter 2012-05-16 18:03 ` Jon Hunter 2012-05-04 15:22 ` Jon Hunter 2012-05-04 15:22 ` Jon Hunter 2012-05-04 15:56 ` Arnd Bergmann 2012-05-04 15:56 ` Arnd Bergmann 2012-05-04 17:19 ` Jon Hunter 2012-05-04 17:19 ` Jon Hunter 2012-05-04 19:06 ` Arnd Bergmann 2012-05-04 19:06 ` Arnd Bergmann 2012-05-04 19:26 ` Jon Hunter 2012-05-04 19:26 ` Jon Hunter 2012-05-04 18:30 ` Stephen Warren 2012-05-04 18:30 ` Stephen Warren
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