[alsa-devel] [PATCH 16/39] firewire-lib: Add some AV/C general commands

[Takashi Sakamoto]

Clemens,

(2014年03月10日 06:32), Clemens Ladisch wrote:
> All these functions return errors with two different mechanisms, the AV/C
> response code or a negative Linux error code.  This forces the caller to
> add a second error check that duplicates the one inside the function:

I realize a need to simplify these return value and decide to work for 
deferred transaction defined in 'AV/C Digital Interface Command Set 
General Specification'. If firewire-lib can handle deferred transaction, 
it's OK that AV/C functions in firewire-lib returns Linux error codes 
instead of combination error codes and response codes.

Well, can I request your comments about corresponding between response 
codes and Linux error codes?

Current my idea is below.

Return codes of CONTROL command:
if (err != 8) /* length of response is out of specification */
	err = -EIO;
else if (buf[0] == 0x08) /* NOT IMPLEMENTED */
	err = -ENOSYS;
else if (buf[0] == 0x0a) /* REJECTED */
	err = -EINVAL;

Return codes of STATUS command:
if (err != 8)  /* length of response is not our expectation */
	err = -EIO;
else if (buf[0] == 0x08) /* NOT IMPLEMENTED */
	err = -ENOSYS;
else if (buf[0] == 0x0a) /* REJECTED */
	err = -EINVAL;
else if (buf[0] == 0x0b) /* IN TRANSITION */
	err = -EAGAIN;

Are these better?


Regards

Takashi Sakamoto
o-takashi at sakamocchi.jp