[PATCH v2] media: cx88-mpeg: clear interrupt status register before streaming video

["Daniel González Cabanelas" <dgcbueu@gmail.com>]

Some cx88 video cards may have transport stream status interrupts set
to 1 from cold start, causing errors like this:

  cx88xx: cx88_print_irqbits: core:irq mpeg  [0x100000] ts_err?*
  cx8802: cx8802_mpeg_irq: mpeg:general errors: 0x00100000

According to CX2388x datasheet, the interrupt status register should be
cleared before enabling IRQs to stream video.

Fix it by clearing the Transport Stream Interrupt Status register.

Signed-off-by: Daniel González Cabanelas <dgcbueu@gmail.com>
---
Changes in v2:
  - Added bits 8 and 12 to the clear operation. Now all documented
    MO_TS_INTSTAT bits are cleared.

 drivers/media/pci/cx88/cx88-mpeg.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/media/pci/cx88/cx88-mpeg.c b/drivers/media/pci/cx88/cx88-mpeg.c
index 680e1e3fe..2c1d5137a 100644
--- a/drivers/media/pci/cx88/cx88-mpeg.c
+++ b/drivers/media/pci/cx88/cx88-mpeg.c
@@ -162,6 +162,9 @@ int cx8802_start_dma(struct cx8802_dev    *dev,
 	cx_write(MO_TS_GPCNTRL, GP_COUNT_CONTROL_RESET);
 	q->count = 0;
 
+	/* clear interrupt status register */
+	cx_write(MO_TS_INTSTAT,  0x1f1111);
+
 	/* enable irqs */
 	dprintk(1, "setting the interrupt mask\n");
 	cx_set(MO_PCI_INTMSK, core->pci_irqmask | PCI_INT_TSINT);
-- 
2.35.1