Re: Problems in 3.3.x with via VT6315
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From: Stefan R. <st...@s5...> - 2012-05-08 19:20:30
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On May 08 Stefan Richter wrote: > One potential cause for never timing out would be if the controller never > gives us an AT-req IRQ ('asynchronous request transmitted' interrupt). > That would be a chip bug against which our drivers are currently not > protected. JMicron JMB38x is known to behave that way; I have particularly > observed it with Coriander (IIDC capture application). However, I have not > yet heard of VIA VT6315 behaving this way. > > (The old driver stack would time out even after missing AT-req IRQ, as > would earlier versions of the newer driver stack --- at the risk of races > with transaction completion though.) > > I'm not saying that this is what happens, just suggesting it as a > possibility. PS, I forgot: A bus reset would flush such stuck requests out (hence Clemens' suggestion to test a bus reset...). But that only works if the controller's self-ID-complete DMA and interrupts still work. Alas, if the controller stopped issuing AT-req IRQs due to whatever fault, chances are limited that it would still issue self-ID-complete IRQs. -- Stefan Richter -=====-===-- -=-= -=--- http://arcgraph.de/sr/ |