Messages in this thread | | | Date | Sat, 07 Feb 2009 01:58:25 +0900 (JST) | Subject | Re: [PATCH 07/13] dmaengine: introduce dma_request_channel and private channels | From | Atsushi Nemoto <> |
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On Fri, 14 Nov 2008 14:34:53 -0700, Dan Williams <dan.j.williams@intel.com> wrote: > To ensure that all channels are not consumed by the general-purpose > allocator the DMA_PRIVATE capability is provided to exclude a dma_device > from general-purpose (memory-to-memory) consideration. ... > + /* Found a suitable channel, try to grab, prep, and > + * return it. We first set DMA_PRIVATE to disable > + * balance_ref_count as this channel will not be > + * published in the general-purpose allocator > + */ > + dma_cap_set(DMA_PRIVATE, device->cap_mask); > + err = dma_chan_get(chan);
The dma_request_channel() set DMA_PRIVATE but dma_release_channel() does not clear it.
If a client (such as dmatest) grabbed a public channel by dma_request_channel(), the channel will stay private forever.
While a dma driver might set DMA_PRIVATE initially for private-only channels, dma_release_channel() cannot clear it unconditionally.
How can this solved? DMA_ALWAYS_PRIVATE or device->is_private or something will needed?
--- Atsushi Nemoto
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