What? Clock Slowdown Again?

What? Clock Slowdown Again?

[Eric Gillespie]

==== Problem One ====
Hi all.  I started noticing the "clock slowdown" problem when I started with
2.4.x series of kernels, and described it in a past post.  In summary, under
framebuffer mode, when the interrupts are disabled, they don't get re-enabled
quickly enough to make sure the system clock keeps up.  I was told about a
patch that would help to solve this, I applied said patch (2.4.3) then, when
the kernel updated to 2.4.11, I was pleased to see the Andrew Morton patch
integrated into the kernel.  

However, I'm noticing the slowdown again, though not to the same extent.  I
took the kernel up to 2.4.17 but I need to do some further tests to see what
else I can ferret out. 

==== Problem Two ====

Also, what are the plans for replacing the virt_to_bus / bus_to_virt
functions?  The sourcecode basically says to use pci_map functions, but, being
almost a kernel illiterate (I know how to compile, apply patches, and not much
else) I don't know how to get started on converting.  I thought that
pci_resource_{start,end,len} may also be needed too.  Am I right?

Again, thanks for all your time.  I read KT and found out about why my 2.5.4
kernel refused to compile, fixed that, fixed another couple of things, then
came up against this bus_to_virt problem, which I'd like to get fixed before I
go anywhere with 2.5 - understandable as I just aout live for my 160x64 text
screen 8-)  I use a VESA framebuffer, as the SiS framebuffer code hasn't been
extended to include the 5597/5598 yet.

Must go...now I can FINALLY send this off, six months after originally
composeng it.

Regards, The Viking
(Please, email me as well, the list takes a VERY long time to read, and I
might miss your post...)

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Re: What? Clock Slowdown Again?

[Francois Romieu]

Eric Gillespie <viking@flying-brick.caverock.net.nz> :
[...]
> Also, what are the plans for replacing the virt_to_bus / bus_to_virt
> functions?  The sourcecode basically says to use pci_map functions, but, being
> almost a kernel illiterate (I know how to compile, apply patches, and not much
> else) I don't know how to get started on converting.  I thought that
> pci_resource_{start,end,len} may also be needed too.  Am I right?

Look at Documentation/DMA-mapping.txt, section "Types of DMA mappings"
Read it again from the start. If you aren't familiar with PCI, 
http://ww.google.com/search?hl=en&q=PCI+dual+address+cycle+explanation may
help. Then look at drivers/net/{epic/eepro100/3c59x}.c and grep for the
functions quoted in DMA-mapping.txt. After that, glue all the pieces in 
your head. 

-- 
Ueimor