Messages in this thread | | | Subject | Re: [PATCH] dmaengine: failure to get a specific DMA channel is not critical | From | "Koul, Vinod" <> | Date | Fri, 24 Jun 2011 16:15:29 +0530 |
| |
On Wed, 2011-06-22 at 10:49 +0900, Magnus Damm wrote: > On Tue, Jun 21, 2011 at 9:19 AM, Kuninori Morimoto > <kuninori.morimoto.gx@renesas.com> wrote: > > > > Dear Guennadi, all > > > >> There exist systems with multiple DMA controllers with different > >> capabilities. For example, on some sh-mobile / rmobile systems there are > >> DMA controllers, whose channels can be configured to be used with > >> SD- and MMC-host controllers, serial ports etc. Besides there are also > >> DMA controllers, that can only be used for one special function, e.g., > >> for USB. In such cases the DMA client filter function can just choose > >> to specify to the DMA driver, which channel it needs. Then the > >> .device_alloc_chan_resources() method of the DMA driver will check, > >> whether it can provide that dunction. If not, it will fail and the loop > >> in __dma_request_channel() will continue to the next DMA device, until > >> it finds a suitable one. This works fine with just one minor glitch: > >> the kernel logs error messages like > >> > >> dmaengine: failed to get <channel name>: (-<error code>) > >> > >> after each such non-critical failure. This patch lowers priority of > >> this message to the debug level. > >> > >> Reported-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> > >> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de> > >> --- > >> > >> Morimoto-san, I don't expect this patch to fail;), but if you like, you > >> could give it a short spin and send your "tested-by" in reply to this > >> mail. > > > > Thanks. > > I tested this patch. > > > > I don't know that the dmaengine design, > > but this patch remove non-critical error message from USB-DMAC for me. > > I tested it on mackerel board + renesas_usbhs + USB-DMAC > > > > Tested-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> > > So I too gave the USBHS + USBHS-DMAC patches a go on top of > linux-3.0-rc and they seem to work as expected. > Without "[PATCH] dmaengine: failure to get a specific DMA channel is > not critical" applied I get the following log: > > / # echo /dev/mtdblock4 > /sys/devices/platform/renesas_usbhs.1/gadget/lun0/file > > [hook up laptop to the USB gadget port] > > / # dmaengine: failed to get dma0chan4: (-22) > dmaengine: failed to get dma1chan0: (-22) > dmaengine: failed to get dma2chan0: (-22) > dmaengine: failed to get dma3chan0: (-22) > dmaengine: failed to get dma0chan4: (-22) > dmaengine: failed to get dma1chan0: (-22) > dmaengine: failed to get dma2chan0: (-22) > dmaengine: failed to get dma3chan0: (-22) > g_mass_storage gadget: high speed config #1: Linux File-Backed Storage > > With this patch applied the "dmaengine: failed to get..." messages all go away. > > Tested-by: Magnus Damm <damm@opensource.se> Applied Thanks.
-- ~Vinod
| |