Messages in this thread | | | Date | Tue, 26 Nov 2013 08:40:28 +0100 | From | Lars-Peter Clausen <> | Subject | Re: [PATCH V2] dma: add common of_dma_slave_xlate() |
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On 11/26/2013 02:25 AM, Stephen Warren wrote: [...] > +struct dma_chan *of_dma_slave_xlate(struct of_phandle_args *dma_spec, > + struct of_dma *ofdma) > +{ > + struct of_dma_slave_xlate_info *info = ofdma->of_dma_data; > + struct dma_chan *candidate, *chan; > + int ret; > + > +retry: > + candidate = NULL; > + > + /* > + * walk the list of channels registered with the current instance and > + * find one that is currently unused > + */ > + list_for_each_entry(chan, &info->device->channels, device_node) > + if (chan->client_count == 0) { > + candidate = chan; > + break; > + } > + > + if (!candidate) > + return NULL; > + > + /* > + * dma_get_slave_channel will return NULL if we lost a race between > + * the lookup and the reservation > + */ > + chan = dma_get_slave_channel(candidate); > + if (!chan) > + goto retry;
I think it will be better to implement this functionality in the core. This means we can hold the dma_list_mutex and don't have to do this retry loop and do not have to peek at the client_count field in non-core code. Something like dma_get_free_slave_channel(), which would call private_candidate() followed by dma_chan_get().
> + > + if (info->post_alloc) { > + ret = info->post_alloc(chan, dma_spec);
If you need to do something at the end of the function I think it is nicer to just wrap this function with your own function instead of adding a callback.
- Lars
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