Appeases the warning "parport0 (bw-qcam): use data_reverse for this!"
Signed-off-by: Brett T. Warden <brett.warden@gmail.com>
---
It seems to work fine with my Quickcam under 2.6.22.
diff --git a/drivers/media/video/bw-qcam.c b/drivers/media/video/bw-qcam.c

index 7d47cbe..01e47ed 100644

--- a/drivers/media/video/bw-qcam.c

+++ b/drivers/media/video/bw-qcam.c

@@ -107,6 +107,11 @@ static inline void write_lpcontrol(struct

qcam_device *q, int d)

        parport_write_control(q->pport, d);

 }
+static inline void reverse_port(struct qcam_device *q)

+{

+       parport_data_reverse(q->pport);

+}

+

 static int qc_waithand(struct qcam_device *q, int val);

 static int qc_command(struct qcam_device *q, int command);

 static int qc_readparam(struct qcam_device *q);

@@ -369,7 +374,11 @@ static void qc_reset(struct qcam_device *q)

                        break;
                case QC_ANY:

-                       write_lpcontrol(q, 0x20);

+                       /*

+                        * Replaced with reverse_port

+                        * write_lpcontrol(q, 0x20);

+                        */

+                       reverse_port(q);

                        write_lpdata(q, 0x75);
                        if (read_lpdata(q) != 0x75) {

@@ -512,10 +521,12 @@ static inline int qc_readbytes(struct

qcam_device *q, char buffer[])

        switch (q->port_mode & QC_MODE_MASK)

        {

                case QC_BIDIR:          /* Bi-directional Port */

-                       write_lpcontrol(q, 0x26);

+                       reverse_port(q);

+                       write_lpcontrol(q, 0x6);

                        lo = (qc_waithand2(q, 1) >> 1);

                        hi = (read_lpstatus(q) >> 3) & 0x1f;

-                       write_lpcontrol(q, 0x2e);

+                       reverse_port(q);

+                       write_lpcontrol(q, 0xe);

                        lo2 = (qc_waithand2(q, 0) >> 1);

                        hi2 = (read_lpst...
[ message continues ]

---

~Randy

Phaedrus says that Quality is about caring.

-

Just as an aside, if you've tested this and it works, then there's no

point to keep the write_lpcontrol even as a comment. Kill those four

lines, and if someone's interested in what happened they'll just look

at the file history.
Ray

-

Point taken, thanks for the feedback.
---
diff --git a/drivers/media/video/bw-qcam.c b/drivers/media/video/bw-qcam.c

index 7d47cbe..0ba92e3 100644

--- a/drivers/media/video/bw-qcam.c

+++ b/drivers/media/video/bw-qcam.c

@@ -107,6 +107,11 @@ static inline void write_lpcontrol(struct

qcam_device *q, int d)

        parport_write_control(q->pport, d);

 }
+static inline void reverse_port(struct qcam_device *q)

+{

+       parport_data_reverse(q->pport);

+}

+

 static int qc_waithand(struct qcam_device *q, int val);

 static int qc_command(struct qcam_device *q, int command);

 static int qc_readparam(struct qcam_device *q);

@@ -369,7 +374,7 @@ static void qc_reset(struct qcam_device *q)

                        break;
                case QC_ANY:

-                       write_lpcontrol(q, 0x20);

+                       reverse_port(q);

                        write_lpdata(q, 0x75);
                        if (read_lpdata(q) != 0x75) {

@@ -512,10 +517,12 @@ static inline int qc_readbytes(struct

qcam_device *q, char buffer[])

        switch (q->port_mode & QC_MODE_MASK)

        {

                case QC_BIDIR:          /* Bi-directional Port */

-                       write_lpcontrol(q, 0x26);

+                       reverse_port(q);

+                       write_lpcontrol(q, 0x6);

                        lo = (qc_waithand2(q, 1) >> 1);

                        hi = (read_lpstatus(q) >> 3) & 0x1f;

-                       write_lpcontrol(q, 0x2e);

+                       reverse_port(q);

+                       write_lpcontrol(q, 0xe);

                        lo2 = (qc_waithand2(q, 0) >> 1);

                        hi2 = (read_lpstatus(q) >> 3) & 0x1f;

                        switch (q->bpp)

@@ -613,10 +620,13 @@ static long qc_capture(struct qcam_device * q,

char __user *buf, unsigned long l
        if ((q->port_mode & QC_MODE_MASK) == QC_BIDIR)

        {

-               write_lpcontrol(q, 0x2e);       /* turn port...
[ message continues ]

Better, and do you have time for two (possibly stupid) questions? In

each of the last cases it looks like the transformation is from a

write_lpcontrol -> reverse_port and a write_lpcontrol (old address -

0x20). Except the first one, which merely has the reverse_port. One

would think that there should be a write_lpcontrol(q, 0x0); after that

one.
Also, is the reverse port sticky, or does it only apply to the next

write? If it's only the next, then maybe a different name would be

better. If it's sticky, then I think the code is wrong...
Ray

-

In response to Randy's and your questions, here's what I understand:
The error message comes from parport_pc_write_control in

include/linux/parport_pc.h, which is called by bw-qcam's

write_lpcontrol():
static __inline__ void parport_pc_write_control (struct parport *p,

                         unsigned char d)

{

    const unsigned char wm = (PARPORT_CONTROL_STROBE |

                  PARPORT_CONTROL_AUTOFD |

                  PARPORT_CONTROL_INIT |

                  PARPORT_CONTROL_SELECT);
    /* Take this out when drivers have adapted to newer interface. */

    if (d & 0x20) {

        printk (KERN_DEBUG "%s (%s): use data_reverse for this!\n",

            p->name, p->cad->name);

        parport_pc_data_reverse (p);

    }
    __parport_pc_frob_control (p, wm, d & wm);

}
The mask wm works out to 0x0f, so first it calls

parport_pc_data_reverse(), then masks off the high nibble with the

reverse flag and makes the regular call.
Looking at that more carefully, I'm not sure whether I need to add the

write_lpcontrol(q, 0) after the first call. Other than that, I believe

I'm following the same procedure.
As for whether data_reverse is sticky, I don't know... I'll see what I

can find out.
--

Brett Warden

-

Fixes use of parport_write_control() to match the newer interface that

requires explicit parport_data_reverse() and parport_data_forward()

calls. This eliminates the following error message and restores the

original intended behavior:
parport0 (bw-qcam): use data_reverse for this!
Also increases threshold in qc_detect() from 300 to 400, as my camera

often results in a count of approx 330. Added a kernel error message

to indicate detection failure.
Signed-off-by: Brett T. Warden <brett.warden@gmail.com>
---
Thanks Ray and Randy for your comments, and for pointing out that I

needed to reset the port to forward mode!
diff --git a/drivers/media/video/bw-qcam.c b/drivers/media/video/bw-qcam.c

index 7d47cbe..961e377 100644

--- a/drivers/media/video/bw-qcam.c

+++ b/drivers/media/video/bw-qcam.c

@@ -104,6 +104,17 @@ static inline void write_lpdata(struct

qcam_device *q, int d)
 static inline void write_lpcontrol(struct qcam_device *q, int d)

 {

+       if(0x20 & d) {

+               /* Set bidirectional mode to reverse (data in) */

+               parport_data_reverse(q->pport);

+       } else {

+               /* Set bidirectional mode to forward (data out) */

+               parport_data_forward(q->pport);

+       }

+

+       /* Now issue the regular port command, but strip out the

+        * direction flag */

+       d &= ~0x20;

        parport_write_control(q->pport, d);

 }
@@ -344,10 +355,13 @@ static int qc_detect(struct qcam_device *q)

        /* Be (even more) liberal in what you accept...  */
 /*     if (count > 30 && count < 200) */

-       if (count > 20 && count < 300)

+       if (count > 20 && count < 400)

+       {

                return 1;       /* found */

-       else

+       } else {

+               printk(KERN_ERR "No Quickcam found on port %s\n",

q->pport->name);

                return 0;       /* not found */

+       }

 }
--

Brett Warden

-

On Thu, 27 Sep 2007 12:28:31 -0700
Acked-by: Alan Cox <alan@redhat.com>

-