[LinuxBIOS] about cs5536 interrupt ack
tiansm at lemote.com
Thu Jul 12 09:26:07 CEST 2007
8259 problem seems to be done with the attached patch, IDE hung seems
to be the dma setting problem.
Thanks all for your advise, comments. I have learned a lot. now I
continue to trace down the IDE problem.
Maciej W. Rozycki wrote:
> On Wed, 11 Jul 2007, Songmao Tian wrote:
>>> Huh? Have you managed to find an 8259A clone *that* broken? So what does
>>> it return if you write 0xc to the address 0x20 in the I/O port space and
>>> then read back from that location? You should complain to the
>> It's the value of IRR, so guess IRR. AMD has well documented cs5536, I
>> appreciate that.
> Indeed. I am surprised they have decided to drop the poll command -- it
> surely does not require much logic as it mostly reuses what's used to
> produce the vector anyway and it is commonly used when 8259A
> implementations are interfaced to non-i386 processors. PPC is another
>>> More or less -- 3-5 should probably be the outcome of a single read
>>> transaction from the north bridge. I.e. you issue a read to a "magic"
>>> location, 3-5 happen, and the data value returned is the vector presented by
>>> the interrupt controller on the PCI bus.
>> yeah, we can implement a register in north bridge.
> Strictly speaking it would not be a register, but a "PCI INTA address
> space" much like PCI memory or I/O port address spaces. Though as the
> former ignores addresses driven on the bus, the space occupied does not
> have to be extensive -- I would assume whatever slot size is available
> with the address decoder you have implemented would do.
>>> You can still dispatch interrupts manually by examining the IRR register,
>>> but having a way to ask the 8259A's prioritiser would be nice. Although
>>> given such a lethal erratum you report I would not count on the prioritiser
>>> to provide any useful flexibility...
>> yeah, that's a straight thought, tried but failed:(, patch followed.
> You may have to modify other functions from arch/mips/kernel/i8259.c;
> yes, this makes the whole experience not as pretty as one would hope...
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