Hello, On Friday, April 08, 2011 10:08 AM Hans Verkuil wrote: > On Friday, April 08, 2011 09:00:55 Marek Szyprowski wrote: > > Hello, > > > > On Monday, April 04, 2011 1:52 PM Hans Verkuil wrote: > > > > > The vb2_poll function would start read DMA if called without any > streaming > > > in progress. This unfortunately does not work if the application just > wants > > > to poll for exceptions. This information of what the application is > polling > > > for is sadly unavailable in the driver. > > > > > > Andy Walls suggested to just return POLLIN | POLLRDNORM and let the > first > > > call to read start the DMA. This initial read() call will return EAGAIN > > > since no actual data is available yet, but it does start the DMA. > > > > The current implementation of vb2_read() will just start streaming on > first > > call without returning EAGAIN. Do you think this should be changed? > > In the non-blocking case vb2_read will also return EAGAIN. Which is what > I meant. So nothing needs to be changed. Right, I got confused again. vb2_read internally calls vb2_dqbuf, which in case of nonblocking io returns EAGAIN. Acked-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> Best regards -- Marek Szyprowski Samsung Poland R&D Center -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
