linux-kernel - Re: [PATCH] bw-qcam: use data_reverse instead of manually poking the control register

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Message-ID: <a372714f0709271228r7de8a4a0p4c5d75e939513f08@mail.gmail.com>
Date:	Thu, 27 Sep 2007 12:28:31 -0700
From:	"Brett Warden" <brett.warden@...il.com>
To:	"Ray Lee" <ray-lk@...rabbit.org>,
	"Randy Dunlap" <randy.dunlap@...cle.com>
Cc:	linux-kernel@...r.kernel.org, trivial@...nel.org
Subject: Re: [PATCH] bw-qcam: use data_reverse instead of manually poking the control register

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@...il.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
-
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