Gerd Knorr wrote: > So IMHO it would be useful to either: > - require driver do support *both* non-blocking I/O and > partial read()s > or > - allow drivers to support only blocking, full-frame read()s. I think I remember now why I didn't want to force partial read() support: 1. A device may not be able to capture in the format required by the application, so the driver is converting when it is copying to the user buffer. A partial read() may not end at a boundary compatible with the conversion routine, e.g. at a partial pixel. That can be worked around by having another buffer to hold the converted data, and then doing the partial read()s from that buffer. 2. There is no guaranteed way for the read()ing thread to know where the frame boundaries are from the read() call alone, especially if the data is compressed by a variable length compression. Bill.
