[linux-dvb] Re: cinergyT2: which kernel/usb module to use?

[Holger Waechtler <holger@qanu.de>]

Hi Johannes, hi Stefan,

Holger Waechtler wrote:

> Johannes Stezenbach wrote:
>
> > > I would hesistate to implement a workaround limiting the number of 
> > > events (e.g. by a synchronous counter incremented by the 
> > > wakeup(poll_wq) call and decremented in the ioctl()) since this 
> > > would just hide application bugs in the future, too and introduce 
> > > new workarounds in every new driver exposing the same behaviour.
> > >   
> >
> > Look, it seems you don't like the API. Fine. But I kindly
> > ask you to play by the rules and implement the same API
> > as the other drivers do. The reason is simple: Interoperability.
> >
> > You don't like how VDR uses the API and want VDR to be changed
> > so it works with your driver? And what about mplayer, xine,
> > kaxtv, mythtv, dvbstream and whatever is out there?
> >
> > I have no problems if you start dvb-kernel-v5 and implement
> > your dream API, but your driver only has a right to be
> > included in dvb-kernel if it maintains API compatibility
> > with the other drivers in dvb-kernel. Period.
> >  
> :) sounds like we need the evil counter-hack to get peace...

can you please try the attached patch and test if it solves your problem?

Holger


btw: Johannes, since the original v3 frontend API was designed by Ralph, 
Andre and me I think it is just fair if the original authors publicly 
announce their criticism, propose changes for future API versions as 
well as implementation recommendations arised out of pasttime 
experiences. Please stop nagging. thanks.

? build-2.4/include/linux
Index: linux/drivers/media/dvb/cinergyT2/cinergyT2.c
===================================================================
RCS file: /cvs/linuxtv/dvb-kernel/linux/drivers/media/dvb/cinergyT2/cinergyT2.c,v
retrieving revision 1.15.2.3
diff -p -u -p -u -r1.15.2.3 cinergyT2.c
--- linux/drivers/media/dvb/cinergyT2/cinergyT2.c	27 Nov 2004 19:15:22 -0000	1.15.2.3
+++ linux/drivers/media/dvb/cinergyT2/cinergyT2.c	29 Nov 2004 18:24:54 -0000
@@ -176,6 +176,7 @@ struct cinergyt2 {
 	struct work_struct query_work;
 
 	wait_queue_head_t poll_wq;
+	int pending_fe_events;
 
 	void *streambuf;
 	dma_addr_t streambuf_dmahandle;
@@ -663,6 +664,12 @@ int cinergyt2_ioctl (struct inode *inode
 		 *  are trivial to fill as soon FE_GET_FRONTEND is done.
 		 */
 		struct dvb_frontend_event *e = (void *) arg;
+		if (cinergyt2->pending_fe_events == 0) {
+			if (file->f_flags & O_NONBLOCK)
+				return -EWOULDBLOCK;
+			wait_event_interruptible(cinergyt2->poll_wq,
+						 cinergyt2->pending_fe_events > 0);
+		}
 		return cinergyt2_ioctl(inode, file, FE_READ_STATUS,
 					(unsigned long) &e->status);
 	}
@@ -695,7 +702,7 @@ int cinergyt2_mmap(struct file *file, st
 		goto bailout;
 	}
 
-        vma->vm_flags |= (VM_IO | VM_DONTCOPY);
+	vma->vm_flags |= (VM_IO | VM_DONTCOPY);
 	vma->vm_file = file;
 
 	ret = remap_pfn_range(vma, vma->vm_start,
@@ -711,11 +718,11 @@ bailout:
 
 static
 struct file_operations cinergyt2_fops = {
-	.owner          = THIS_MODULE,
+	.owner		= THIS_MODULE,
 	.ioctl		= cinergyt2_ioctl,
-	.poll           = cinergyt2_poll,
-	.open           = cinergyt2_open,
-	.release        = cinergyt2_release,
+	.poll		= cinergyt2_poll,
+	.open		= cinergyt2_open,
+	.release	= cinergyt2_release,
 /*	.mmap		= cinergyt2_mmap*/
 };
 
@@ -800,8 +807,10 @@ static void cinergyt2_query (void *data)
 	unc += le32_to_cpu(s->uncorrected_block_count);
 	s->uncorrected_block_count = unc;
 
-	if (lock_bits != s->lock_bits)
+	if (lock_bits != s->lock_bits) {
 		wake_up_interruptible(&cinergyt2->poll_wq);
+		cinergyt2->pending_fe_events++;
+	}
 
 	schedule_delayed_work(&cinergyt2->query_work,
 			      msecs_to_jiffies(QUERY_INTERVAL));