[linux-dvb] SAA7146 short delay flag and budget cards

Carlo E. Prelz fluido at fluido.as
Wed Sep 21 09:12:10 CEST 2005


Good morning. After moving to an AMD64 system and kernel 2.6.14rc1,
plus last Saturday's CVS dvb drivers, I found that, while talking with
my hauppauge DVB-S budget card, delays for frontend IOCTL's
(FE_READ_STATUS, FE_READ_SNR and FE_READ_SIGNAL_STRENGTH) were
unexpectedly increased. Each ioctl took 200-400 milliseconds to
return. After a long and painful search, I found out that the delay
happened in I2C comms. I noticed that, in av7110.c, a flag was set,
called SAA7146_I2C_SHORT_DELAY, in the saa7146_extension
structure. So, I applied the following simple patch:

--- budget.c~   2005-09-04 14:58:21.000000000 +0200
+++ budget.c    2005-09-17 23:28:14.000000000 +0200
@@ -740,7 +740,7 @@

 static struct saa7146_extension budget_extension = {
        .name           = "budget dvb\0",
-       .flags          = 0,
+       .flags          = SAA7146_I2C_SHORT_DELAY,

        .module         = THIS_MODULE,
        .pci_tbl        = pci_tbl,

Well, the card now reacts *very* quickly, and I do not notice any side
effects. 

Is there any reason why this flag is not set?

Carlo

-- 
  *         Se la Strada e la sua Virtu' non fossero state messe da parte,
* K * Carlo E. Prelz - fluido at fluido.as             che bisogno ci sarebbe
  *               di parlare tanto di amore e di rettitudine? (Chuang-Tzu)



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