On 12/27/2011 13:34, Stephen Hemminger wrote:
> On Tue, 27 Dec 2011 00:06:15 -0500
> Joshua Kinard <kumba@xxxxxxxxxx> wrote:
>
>> @@ -95,7 +95,7 @@ struct mace_video {
>> * Ethernet interface
>> */
>> struct mace_ethernet {
>> - volatile unsigned long mac_ctrl;
>> + volatile u64 mac_ctrl;
>> volatile unsigned long int_stat;
>> volatile unsigned long dma_ctrl;
>> volatile unsigned long timer;
>
>
> This device driver writer needs to read:
> Documentation/volatile-considered-harmful.txt
MIPS I/O registers are always memory-mapped, and to prevent the compiler
from trying to over-optimize, volatile is used to make sure we always read a
value from the hardware and not from some cached value.
See MIPS Run (2nd Ed), pp 307, section 10.5.2 highlights an example of this,
which is viewable here:
http://books.google.com/books?id=kk8G2gK4Tw8C&pg=PA307&lpg=PA308#v=onepage&q&f=false
But other than that, yeah, this driver needs to pretty much be stripped down
to the nuts and bolts and re-written. Maybe something to tackle in the
future. I still haven't gotten around to submitting the RTC driver for O2's
(that I re-wrote from a patch sent into LKML years ago) upstream yet.
--
Joshua Kinard
Gentoo/MIPS
kumba@xxxxxxxxxx
4096R/D25D95E3 2011-03-28
"The past tempts us, the present confuses us, the future frightens us. And
our lives slip away, moment by moment, lost in that vast, terrible in-between."
--Emperor Turhan, Centauri Republic
