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[PATCH] ub: fix for blank CDs
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This patch fixes a microcode lockup in my CD-ROM adapters when a blank CD
is inserted.  However, do not try to burn CDs yet!  I'm pretty sure that
trying it will end in coasters.

 - Fix a few cases where we were unable to resynchronize with replies
   for previous commands. The main thing is to keep reading replies
   in case of a stall. This is done with the new state CLRRS.
 - Since I am forgetting the basic state machine already, document it.
 - Move counter increments in the looping path in its own function.
 - Fix a harmless buglet in case CSW read fails to submit: do not
   override state.
 - Implement the Alan Stern's idea for adaptive signature checking.

Signed-off-by: Pete Zaitcev <[email protected]>
Cc: Greg KH <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Pete Zaitcev authored and Linus Torvalds committed Jul 27, 2005
1 parent 90c5029 commit 1872bce
Showing 1 changed file with 170 additions and 41 deletions.
211 changes: 170 additions & 41 deletions drivers/block/ub.c
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@
* -- Exterminate P3 printks
* -- Resove XXX's
* -- Redo "benh's retries", perhaps have spin-up code to handle them. V:D=?
* -- CLEAR, CLR2STS, CLRRS seem to be ripe for refactoring.
*/
#include <linux/kernel.h>
#include <linux/module.h>
Expand All @@ -37,6 +38,73 @@

#define UB_MAJOR 180

/*
* The command state machine is the key model for understanding of this driver.
*
* The general rule is that all transitions are done towards the bottom
* of the diagram, thus preventing any loops.
*
* An exception to that is how the STAT state is handled. A counter allows it
* to be re-entered along the path marked with [C].
*
* +--------+
* ! INIT !
* +--------+
* !
* ub_scsi_cmd_start fails ->--------------------------------------\
* ! !
* V !
* +--------+ !
* ! CMD ! !
* +--------+ !
* ! +--------+ !
* was -EPIPE -->-------------------------------->! CLEAR ! !
* ! +--------+ !
* ! ! !
* was error -->------------------------------------- ! --------->\
* ! ! !
* /--<-- cmd->dir == NONE ? ! !
* ! ! ! !
* ! V ! !
* ! +--------+ ! !
* ! ! DATA ! ! !
* ! +--------+ ! !
* ! ! +---------+ ! !
* ! was -EPIPE -->--------------->! CLR2STS ! ! !
* ! ! +---------+ ! !
* ! ! ! ! !
* ! ! was error -->---- ! --------->\
* ! was error -->--------------------- ! ------------- ! --------->\
* ! ! ! ! !
* ! V ! ! !
* \--->+--------+ ! ! !
* ! STAT !<--------------------------/ ! !
* /--->+--------+ ! !
* ! ! ! !
* [C] was -EPIPE -->-----------\ ! !
* ! ! ! ! !
* +<---- len == 0 ! ! !
* ! ! ! ! !
* ! was error -->--------------------------------------!---------->\
* ! ! ! ! !
* +<---- bad CSW ! ! !
* +<---- bad tag ! ! !
* ! ! V ! !
* ! ! +--------+ ! !
* ! ! ! CLRRS ! ! !
* ! ! +--------+ ! !
* ! ! ! ! !
* \------- ! --------------------[C]--------\ ! !
* ! ! ! !
* cmd->error---\ +--------+ ! !
* ! +--------------->! SENSE !<----------/ !
* STAT_FAIL----/ +--------+ !
* ! ! V
* ! V +--------+
* \--------------------------------\--------------------->! DONE !
* +--------+
*/

/*
* Definitions which have to be scattered once we understand the layout better.
*/
Expand Down Expand Up @@ -91,8 +159,6 @@ struct bulk_cs_wrap {

#define US_BULK_CS_WRAP_LEN 13
#define US_BULK_CS_SIGN 0x53425355 /* spells out 'USBS' */
/* This is for Olympus Camedia digital cameras */
#define US_BULK_CS_OLYMPUS_SIGN 0x55425355 /* spells out 'USBU' */
#define US_BULK_STAT_OK 0
#define US_BULK_STAT_FAIL 1
#define US_BULK_STAT_PHASE 2
Expand Down Expand Up @@ -135,6 +201,7 @@ enum ub_scsi_cmd_state {
UB_CMDST_CLR2STS, /* Clearing before requesting status */
UB_CMDST_STAT, /* Status phase */
UB_CMDST_CLEAR, /* Clearing a stall (halt, actually) */
UB_CMDST_CLRRS, /* Clearing before retrying status */
UB_CMDST_SENSE, /* Sending Request Sense */
UB_CMDST_DONE /* Final state */
};
Expand All @@ -146,6 +213,7 @@ static char *ub_scsi_cmd_stname[] = {
"c2s",
"sts",
"clr",
"crs",
"Sen",
"fin"
};
Expand Down Expand Up @@ -316,6 +384,7 @@ struct ub_dev {
struct urb work_urb;
struct timer_list work_timer;
int last_pipe; /* What might need clearing */
__le32 signature; /* Learned signature */
struct bulk_cb_wrap work_bcb;
struct bulk_cs_wrap work_bcs;
struct usb_ctrlrequest work_cr;
Expand All @@ -339,8 +408,9 @@ static void ub_scsi_action(unsigned long _dev);
static void ub_scsi_dispatch(struct ub_dev *sc);
static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_state_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd, int rc);
static void __ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static int __ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_state_stat_counted(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_state_sense(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static int ub_submit_clear_stall(struct ub_dev *sc, struct ub_scsi_cmd *cmd,
int stalled_pipe);
Expand Down Expand Up @@ -1085,6 +1155,28 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)

ub_state_stat(sc, cmd);

} else if (cmd->state == UB_CMDST_CLRRS) {
if (urb->status == -EPIPE) {
/*
* STALL while clearning STALL.
* The control pipe clears itself - nothing to do.
* XXX Might try to reset the device here and retry.
*/
printk(KERN_NOTICE "%s: stall on control pipe\n",
sc->name);
goto Bad_End;
}

/*
* We ignore the result for the halt clear.
*/

/* reset the endpoint toggle */
usb_settoggle(sc->dev, usb_pipeendpoint(sc->last_pipe),
usb_pipeout(sc->last_pipe), 0);

ub_state_stat_counted(sc, cmd);

} else if (cmd->state == UB_CMDST_CMD) {
if (urb->status == -EPIPE) {
rc = ub_submit_clear_stall(sc, cmd, sc->last_pipe);
Expand Down Expand Up @@ -1190,52 +1282,57 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
*/
goto Bad_End;
}
cmd->state = UB_CMDST_CLEAR;

/*
* Having a stall when getting CSW is an error, so
* make sure uppper levels are not oblivious to it.
*/
cmd->error = -EIO; /* A cheap trick... */

cmd->state = UB_CMDST_CLRRS;
ub_cmdtr_state(sc, cmd);
return;
}
if (urb->status == -EOVERFLOW) {
/*
* XXX We are screwed here. Retrying is pointless,
* because the pipelined data will not get in until
* we read with a big enough buffer. We must reset XXX.
*/
goto Bad_End;
}
if (urb->status != 0)
goto Bad_End;

if (urb->actual_length == 0) {
/*
* Some broken devices add unnecessary zero-length
* packets to the end of their data transfers.
* Such packets show up as 0-length CSWs. If we
* encounter such a thing, try to read the CSW again.
*/
if (++cmd->stat_count >= 4) {
printk(KERN_NOTICE "%s: unable to get CSW\n",
sc->name);
goto Bad_End;
}
__ub_state_stat(sc, cmd);
ub_state_stat_counted(sc, cmd);
return;
}

/*
* Check the returned Bulk protocol status.
* The status block has to be validated first.
*/

bcs = &sc->work_bcs;
rc = le32_to_cpu(bcs->Residue);
if (rc != cmd->len - cmd->act_len) {

if (sc->signature == cpu_to_le32(0)) {
/*
* It is all right to transfer less, the caller has
* to check. But it's not all right if the device
* counts disagree with our counts.
* This is the first reply, so do not perform the check.
* Instead, remember the signature the device uses
* for future checks. But do not allow a nul.
*/
/* P3 */ printk("%s: resid %d len %d act %d\n",
sc->name, rc, cmd->len, cmd->act_len);
goto Bad_End;
}

#if 0
if (bcs->Signature != cpu_to_le32(US_BULK_CS_SIGN) &&
bcs->Signature != cpu_to_le32(US_BULK_CS_OLYMPUS_SIGN)) {
/* Windows ignores signatures, so do we. */
sc->signature = bcs->Signature;
if (sc->signature == cpu_to_le32(0)) {
ub_state_stat_counted(sc, cmd);
return;
}
} else {
if (bcs->Signature != sc->signature) {
ub_state_stat_counted(sc, cmd);
return;
}
}
#endif

if (bcs->Tag != cmd->tag) {
/*
Expand All @@ -1245,16 +1342,22 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
* commands and reply at commands we timed out before.
* Without flushing these replies we loop forever.
*/
if (++cmd->stat_count >= 4) {
printk(KERN_NOTICE "%s: "
"tag mismatch orig 0x%x reply 0x%x\n",
sc->name, cmd->tag, bcs->Tag);
goto Bad_End;
}
__ub_state_stat(sc, cmd);
ub_state_stat_counted(sc, cmd);
return;
}

rc = le32_to_cpu(bcs->Residue);
if (rc != cmd->len - cmd->act_len) {
/*
* It is all right to transfer less, the caller has
* to check. But it's not all right if the device
* counts disagree with our counts.
*/
/* P3 */ printk("%s: resid %d len %d act %d\n",
sc->name, rc, cmd->len, cmd->act_len);
goto Bad_End;
}

switch (bcs->Status) {
case US_BULK_STAT_OK:
break;
Expand All @@ -1272,6 +1375,10 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
}

/* Not zeroing error to preserve a babble indicator */
if (cmd->error != 0) {
ub_state_sense(sc, cmd);
return;
}
cmd->state = UB_CMDST_DONE;
ub_cmdtr_state(sc, cmd);
ub_cmdq_pop(sc);
Expand Down Expand Up @@ -1310,7 +1417,7 @@ static void ub_state_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd, int rc)
* Factorization helper for the command state machine:
* Submit a CSW read.
*/
static void __ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
static int __ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
int rc;

Expand All @@ -1328,11 +1435,12 @@ static void __ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
/* XXX Clear stalls */
ub_complete(&sc->work_done);
ub_state_done(sc, cmd, rc);
return;
return -1;
}

sc->work_timer.expires = jiffies + UB_STAT_TIMEOUT;
add_timer(&sc->work_timer);
return 0;
}

/*
Expand All @@ -1341,13 +1449,34 @@ static void __ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
*/
static void ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
__ub_state_stat(sc, cmd);

if (__ub_state_stat(sc, cmd) != 0)
return;

cmd->stat_count = 0;
cmd->state = UB_CMDST_STAT;
ub_cmdtr_state(sc, cmd);
}

/*
* Factorization helper for the command state machine:
* Submit a CSW read and go to STAT state with counter (along [C] path).
*/
static void ub_state_stat_counted(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{

if (++cmd->stat_count >= 4) {
ub_state_sense(sc, cmd);
return;
}

if (__ub_state_stat(sc, cmd) != 0)
return;

cmd->state = UB_CMDST_STAT;
ub_cmdtr_state(sc, cmd);
}

/*
* Factorization helper for the command state machine:
* Submit a REQUEST SENSE and go to SENSE state.
Expand Down

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