Re: [BUG] ATAPI command TEST_UNIT_READY never succeeds!

["Conke Hu" <conke.hu@gmail.com>]

On 3/7/07, Tejun Heo <htejun@gmail.com> wrote:
> (snip)
> I've read your last posting about this, but forgot to follow up.  TUR is
> supposed to fail if ATAPI device doesn't have media loaded.  TUR fails
> and sense data returns device not ready - media not present.  That's the
> normal operation.  Does TUR fail even with media loaded or is sense data
> not properly fetched?
>

Thank you, Tejun! I did forget to load any media :(
When I load media and retry, TUR succeeds but there is still a
problem: when using ahci driver, TUR will not succeed unless it runs
twice, and the following loop always runs till retries==2
-------------------- code in sr.c, get_capabilities() -------------------------
	retries = 0;
	do {
		memset((void *)cmd, 0, MAX_COMMAND_SIZE);
		cmd[0] = TEST_UNIT_READY;

		the_result = scsi_execute_req (cd->device, cmd, DMA_NONE, NULL,
					       0, &sshdr, SR_TIMEOUT,
					       MAX_RETRIES);

		retries++;
	} while (retries < 5 &&
		 (!scsi_status_is_good(the_result) ||
		  (scsi_sense_valid(&sshdr) &&
		   sshdr.sense_key == UNIT_ATTENTION)));
------------------------------------- end code
-------------------------------------

this issue only occurs in ahci driver,  and libata + pata driver is OK.

Conke