V4L/DVB (5578): Workaround for bad hardare/firmware on some pluto2 devices

pluto2_driver: Workaround for pluto2 card reporting wrong number of
received packets and flooding system with interrupts.

This patch constitutes a workaround for a hardware/firmware problem of the
pluto2-based card (e.g., Satelco EasyWatch).

It can happen in rare cases that the card gets into a mode where it
always reports back a number of received packets (nbpackets) which is
larger than the maximum permissible number of packets (TS_DMA_PACKETS).
The workaround that is already in the driver in function pluto_dma_end
reports back zero received packets. In spite of the (in reality) zero
received packets the card continues to generate interrupts at a very
high rate, which can effectively stall the system.

The patch resets the TS logic, which puts the card back into normal
operations.

Signed-off-by: Holger Magnussen <holger@muscate-magnussen.de>
Signed-off-by: Andreas Oberritter <obi@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

diff --git a/drivers/media/dvb/pluto2/pluto2.c b/drivers/media/dvb/pluto2/pluto2.c
index 058df5c100348b89657c79ede7772054444ee42f..08a2599ed74a7463293ae0e8858642fd6b495d84 100644 (file)
--- a/drivers/media/dvb/pluto2/pluto2.c
+++ b/drivers/media/dvb/pluto2/pluto2.c
@@ -293,12 +293,20 @@ static void pluto_dma_end(struct pluto *pluto, unsigned int nbpackets)
         *     but no packets have been transfered.
         * [2] Sometimes (actually very often) NBPACKETS stays at zero
         *     although one packet has been transfered.
+        * [3] Sometimes (actually rarely), the card gets into an erroneous
+        *     mode where it continuously generates interrupts, claiming it
+        *     has recieved nbpackets>TS_DMA_PACKETS packets, but no packet
+        *     has been transfered. Only a reset seems to solve this
         */
        if ((nbpackets == 0) || (nbpackets > TS_DMA_PACKETS)) {
                unsigned int i = 0;
                while (pluto->dma_buf[i] == 0x47)
                        i += 188;
                nbpackets = i / 188;
+               if (i == 0) {
+                       pluto_reset_ts(pluto, 1);
+                       dev_printk(KERN_DEBUG, &pluto->pdev->dev, "resetting TS because of invalid packet counter\n");
+               }
        }
 
        dvb_dmx_swfilter_packets(&pluto->demux, pluto->dma_buf, nbpackets);