Re: [patch] libata passthrough - return register data from HDIO_* commands

[Jon Escombe <lists@dresco.co.uk>]

[-- Attachment #1: Type: text/plain, Size: 1244 bytes --]


> Here is a first attempt at a patch to return register data from the 
> libata passthrough HDIO ioctl handlers, I needed this as the ATA 
> 'unload immediate' command returns the success in the lbal register. 
> This patch applies on top of 2.6.12 and Jeffs 
> 2.6.12-git4-passthru1.patch. (Apologies, but Thunderbird appears to 
> have replaced the tabs with spaces).
>
> One oddity is that the sr_result field is correctly being set in 
> ata_gen_ata_desc_sense(), however the high word is different when 
> we're back in the ioctl hander. I've coded round this for now by only 
> checking the low word, but this needs more investigation.
>
> Jeff, could this functionality be incorporated into the pasthrough 
> patch when complete?


I'd failed to realise that scsi_finish_command() sets the high byte of 
the result field to DRIVER_SENSE when there is sense data. Patch updated 
to reflect this...

Haven't had any feedback on the patch itself - but this now does what I 
wanted it do to.  (I can't find a way to make Thunderbird retain tabs in 
the message body, so sending as an attachment).

Regards,
Jon.



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[-- Attachment #2: passthrough_check_condition.patch --]
[-- Type: text/x-patch, Size: 3001 bytes --]

--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -89,6 +89,7 @@
 	u8 args[4], *argbuf = NULL;
 	int argsize = 0;
 	struct scsi_request *sreq;
+	unsigned char *sb, *desc;
 
 	if (NULL == (void *)arg)
 		return -EINVAL;
@@ -100,6 +101,9 @@
 	if (!sreq)
 		return -EINTR;
 
+	sb = sreq->sr_sense_buffer;
+	desc = sb + 8;
+
 	memset(scsi_cmd, 0, sizeof(scsi_cmd));
 
 	if (args[3]) {
@@ -109,12 +113,12 @@
 			return -ENOMEM;
 
 		scsi_cmd[1]  = (4 << 1); /* PIO Data-in */
-		scsi_cmd[2]  = 0x0e;     /* no off.line or cc, read from dev,
+		scsi_cmd[2]  = 0x2e;     /* no off.line, read from dev, request cc
 		                            block count in sector count field */
 		sreq->sr_data_direction = DMA_FROM_DEVICE;
 	} else {
 		scsi_cmd[1]  = (3 << 1); /* Non-data */
-		/* scsi_cmd[2] is already 0 -- no off.line, cc, or data xfer */
+		scsi_cmd[2]  = 0x20;     /* no off.line or data xfer, request check condtion */
 		sreq->sr_data_direction = DMA_NONE;
 	}
 
@@ -135,16 +139,24 @@
 	   from scsi_ioctl_send_command() for default case... */
 	scsi_wait_req(sreq, scsi_cmd, argbuf, argsize, (10*HZ), 5);
 
-	if (sreq->sr_result) {
+	if (!sreq->sr_result == ((DRIVER_SENSE << 24) + SAM_STAT_CHECK_CONDITION)) {
 		rc = -EIO;
 		goto error;
 	}
 
-	/* Need code to retrieve data from check condition? */
+	/* Retrieve data from check condition */
+	args[1] = desc[3];
+	args[2] = desc[5];
+	args[3] = desc[7];
+	args[4] = desc[9];
+	args[5] = desc[11];
+	args[0] = desc[13];
 
 	if ((argbuf)
 	 && copy_to_user((void *)(arg + sizeof(args)), argbuf, argsize))
 		rc = -EFAULT;
+	if (copy_to_user(arg, args, sizeof(args)))
+		rc = -EFAULT;
 error:
 	scsi_release_request(sreq);
 
@@ -171,6 +183,7 @@
 	u8 scsi_cmd[MAX_COMMAND_SIZE];
 	u8 args[7];
 	struct scsi_request *sreq;
+	unsigned char *sb, *desc;
 
 	if (NULL == (void *)arg)
 		return -EINVAL;
@@ -181,7 +194,7 @@
 	memset(scsi_cmd, 0, sizeof(scsi_cmd));
 	scsi_cmd[0]  = ATA_16;
 	scsi_cmd[1]  = (3 << 1); /* Non-data */
-	/* scsi_cmd[2] is already 0 -- no off.line, cc, or data xfer */
+	scsi_cmd[2]  = 0x20;     /* no off.line, or data xfer, request cc */
 	scsi_cmd[4]  = args[1];
 	scsi_cmd[6]  = args[2];
 	scsi_cmd[8]  = args[3];
@@ -195,18 +208,29 @@
 		goto error;
 	}
 
+	sb = sreq->sr_sense_buffer;
+	desc = sb + 8;
+
 	sreq->sr_data_direction = DMA_NONE;
 	/* Good values for timeout and retries?  Values below
 	   from scsi_ioctl_send_command() for default case... */
 	scsi_wait_req(sreq, scsi_cmd, NULL, 0, (10*HZ), 5);
 
-	if (sreq->sr_result) {
+	if (!sreq->sr_result == ((DRIVER_SENSE << 24) + SAM_STAT_CHECK_CONDITION)) {
 		rc = -EIO;
 		goto error;
 	}
 
-	/* Need code to retrieve data from check condition? */
+	/* Retrieve data from check condition */
+	args[1] = desc[3];
+	args[2] = desc[5];
+	args[3] = desc[7];
+	args[4] = desc[9];
+	args[5] = desc[11];
+	args[0] = desc[13];
 
+	if (copy_to_user(arg, args, sizeof(args)))
+		rc = -EFAULT;
 error:
 	scsi_release_request(sreq);
 	return rc;