[PATCH] bw-qcam: Adds module parameter 'aggressive' to skip polite auto-detection prior to direct initialization.

[PATCH] bw-qcam: Adds module parameter 'aggressive' to skip polite auto-detection prior to direct initialization.

[Brett T. Warden]

Setting aggressive=1 bypasses the friendly auto-detection by polling the status register, and instead attempts to initialize the qcam directly. Not friendly to other parallel devices, but much more reliable than the auto-detection.

Signed-off-by: Brett T. Warden <brett.warden@gmail.com>
---
 drivers/media/video/bw-qcam.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/drivers/media/video/bw-qcam.c b/drivers/media/video/bw-qcam.c
index 5842352..b74a9cb 100644
--- a/drivers/media/video/bw-qcam.c
+++ b/drivers/media/video/bw-qcam.c
@@ -82,11 +82,16 @@ OTHER DEALINGS IN THE SOFTWARE.
 static unsigned int maxpoll=250;   /* Maximum busy-loop count for qcam I/O */
 static unsigned int yieldlines=4;  /* Yield after this many during capture */
 static int video_nr = -1;
+static unsigned int aggressive;		/* Whether to probe aggressively */
 
 module_param(maxpoll, int, 0);
 module_param(yieldlines, int, 0);
 module_param(video_nr, int, 0);
 
+/* Set aggressive=1 to avoid detection by polling status register and
+ * immediately attempt to initialize qcam */
+module_param(aggressive, int, 0);
+
 static inline int read_lpstatus(struct qcam_device *q)
 {
 	return parport_read_status(q->pport);
@@ -331,6 +336,9 @@ static int qc_detect(struct qcam_device *q)
 	int count = 0;
 	int i;
 
+	if (aggressive)
+		return 1;
+
 	lastreg = reg = read_lpstatus(q) & 0xf0;
 
 	for (i = 0; i < 500; i++)
@@ -354,12 +362,12 @@ 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 < 400) {
 		return 1;	/* found */
 	} else {
 		printk(KERN_ERR "No Quickcam found on port %s\n",
 			q->pport->name);
+		printk(KERN_DEBUG "Quickcam detection counter: %u\n", count);
 		return 0;	/* not found */
 	}
 }
-- 
1.5.2.5

Re: [PATCH] bw-qcam: Adds module parameter 'aggressive' to skip polite auto-detection prior to direct initialization.

[Alan Cox]

On Tue,  4 Dec 2007 16:44:41 -0800
"Brett T. Warden" <brett.warden@gmail.com> wrote:

> Setting aggressive=1 bypasses the friendly auto-detection by polling the status register, and instead attempts to initialize the qcam directly. Not friendly to other parallel devices, but much more reliable than the auto-detection.

Someone still has a bw-qcam device ?

The status polling ought to be rock solid - what values do you see ?

Re: [PATCH] bw-qcam: Adds module parameter 'aggressive' to skip polite auto-detection prior to direct initialization.

[Brett Warden]

Sorry, forgot to copy back to the lists.

On Dec 5, 2007 8:49 AM, Brett Warden <brett.warden@gmail.com> wrote:
> On Dec 4, 2007 4:46 PM, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> >
> > Someone still has a bw-qcam device ?
>
> Yes. I haven't found a better option for very-low-light, although I
> admit I haven't looked in a long while. The last one I tried was an
> OV518+, but of course that driver seems to have been abandoned.
>
> > The status polling ought to be rock solid - what values do you see ?
>
> It has been as high as 94-96, but after being connected, powered, and
> used for a while, it drops sometimes into the 40s, but has even been
> as low as 8-14. When it's that low, it never comes back up until
> either I disconnect/reconnect the power, or I force the driver to
> initialize it through this hack. Even after trying that again just
> now, it's ranging from 24-33.
>
> --
> Brett Warden
>



-- 
Brett Warden

[PATCH] bw-qcam: Adds module parameter 'aggressive' to skip polite auto-detection prior to direct initialization.

[Brett T. Warden]

Setting aggressive=1 bypasses the friendly auto-detection by polling the status register, and instead attempts to initialize the qcam directly. Not friendly to other parallel devices, but much more reliable than the auto-detection.

Signed-off-by: Brett T. Warden <brett.warden@gmail.com>
---
 drivers/media/video/bw-qcam.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/drivers/media/video/bw-qcam.c b/drivers/media/video/bw-qcam.c
index 5842352..b74a9cb 100644
--- a/drivers/media/video/bw-qcam.c
+++ b/drivers/media/video/bw-qcam.c
@@ -82,11 +82,16 @@ OTHER DEALINGS IN THE SOFTWARE.
 static unsigned int maxpoll=250;   /* Maximum busy-loop count for qcam I/O */
 static unsigned int yieldlines=4;  /* Yield after this many during capture */
 static int video_nr = -1;
+static unsigned int aggressive;		/* Whether to probe aggressively */
 
 module_param(maxpoll, int, 0);
 module_param(yieldlines, int, 0);
 module_param(video_nr, int, 0);
 
+/* Set aggressive=1 to avoid detection by polling status register and
+ * immediately attempt to initialize qcam */
+module_param(aggressive, int, 0);
+
 static inline int read_lpstatus(struct qcam_device *q)
 {
 	return parport_read_status(q->pport);
@@ -331,6 +336,9 @@ static int qc_detect(struct qcam_device *q)
 	int count = 0;
 	int i;
 
+	if (aggressive)
+		return 1;
+
 	lastreg = reg = read_lpstatus(q) & 0xf0;
 
 	for (i = 0; i < 500; i++)
@@ -354,12 +362,12 @@ 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 < 400) {
 		return 1;	/* found */
 	} else {
 		printk(KERN_ERR "No Quickcam found on port %s\n",
 			q->pport->name);
+		printk(KERN_DEBUG "Quickcam detection counter: %u\n", count);
 		return 0;	/* not found */
 	}
 }
-- 
1.5.3.7