Re: [PATCH, RFC] Driver for reading HP laptop LCD brightness

[Matthew Garrett]

On Sun, Feb 05, 2006 at 03:27:26PM +0100, Arjan van de Ven wrote:

> disable_irq() and enable_irq() are really really evil. Are you sure you
> need these? To me on first sight it looks like a bug (think of shared
> interrupts for example), can you explain what you are trying to achieve
> with these?

We're talking to the hardware directly. There's a potential race where 
the BIOS will try to access the cmos at the same time, with potentially 
interesting results (We set the address we want to read with the outb. 
The BIOS runs, outbs its own address, and then reads. We then read from 
the address the BIOS was looking at, rather than what we were looking 
at).

On all the hardware this will run on, IRQ 8 is the RTC. I don't believe 
it can share interrupts.
-- 
Matthew Garrett | mjg59@xxxxxxxxxxxxx
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