V4L/DVB (7013): bw-qcam: add module parameter 'force_init' to skip polite auto-detection prior to direct initialization

Setting force_init=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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 9 insertions, 1 deletions

diff --git a/drivers/media/video/bw-qcam.c b/drivers/media/video/bw-qcam.c
index 58423525591f..032265383df2 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 force_init;         /* Whether to probe aggressively */
 
 module_param(maxpoll, int, 0);
 module_param(yieldlines, int, 0);
 module_param(video_nr, int, 0);
 
+/* Set force_init=1 to avoid detection by polling status register and
+ * immediately attempt to initialize qcam */
+module_param(force_init, 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 (force_init)
+                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 */
         }
 }