[PATCH 09/10] staging: comedi: simplify returned errors for comedi_read()

In order to perform a "read" file operation, an asynchronous COMEDI command in the "read" direction needs to have been set up by the current file object on the COMEDI "read" subdevice associated with the file object. If there is a "read" subdevice, but a command has not been set up by the file

[PATCH 09/10] staging: comedi: simplify returned errors for comedi_read()

In order to perform a "read" file operation, an asynchronous COMEDI command in the "read" direction needs to have been set up by the current file object on the COMEDI "read" subdevice associated with the file object. If there is a "read" subdevice, but a command has not been set up by the file