[media] cx23885[v4]: Fix interrupt storm when enabling IR receiver

Apparently the Flatiron genereates an interrupt after the built-in self
test for each of its left and right channels has completed.

Apparently Conexant wire-OR'ed the Flatiron's interrupt output with the
interrupt output of the CX23885 A/V core.

Those interrupts need to be handled, otherwise, they generate an
interrrupt request storm.

So:

- Add flatiron readreg and writereg functions prototypes
  on a new header file;
- Modify the av interrupt handler to cleanup flatiron IRQs if no other
  interrupt handling happens.

Signed-off-by: Luis Alves <ljalvs@gmail.com>
Acked-by: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/media/pci/cx23885/cx23885-av.c b/drivers/media/pci/cx23885/cx23885-av.c
index e958a01fd554..c443b7ac5adf 100644
--- a/drivers/media/pci/cx23885/cx23885-av.c
+++ b/drivers/media/pci/cx23885/cx23885-av.c
@@ -23,6 +23,7 @@
 
 #include "cx23885.h"
 #include "cx23885-av.h"
+#include "cx23885-video.h"
 
 void cx23885_av_work_handler(struct work_struct *work)
 {
@@ -32,5 +33,17 @@ void cx23885_av_work_handler(struct work_struct *work)
 
 	v4l2_subdev_call(dev->sd_cx25840, core, interrupt_service_routine,
 			 PCI_MSK_AV_CORE, &handled);
+
+	/* Getting here with the interrupt not handled
+	   then probbaly flatiron does have pending interrupts.
+	*/
+	if (!handled) {
+		/* clear left and right adc channel interrupt request flag */
+		cx23885_flatiron_write(dev, 0x1f,
+			cx23885_flatiron_read(dev, 0x1f) | 0x80);
+		cx23885_flatiron_write(dev, 0x23,
+			cx23885_flatiron_read(dev, 0x23) | 0x80);
+	}
+
 	cx23885_irq_enable(dev, PCI_MSK_AV_CORE);
 }