Re: [RFC] pata_icside driver

[Russell King]

On Mon, Apr 09, 2007 at 01:24:45AM -0700, Roland Dreier wrote:
>  > Lets say that we want to do MW DMA mode 2.  This has the minimum timing
>  > of 70ns active, 25ns recovery, 120ns cycle time.
>  > 
>  > When you quantise those figures using a clock period of 62.5ns (16MHz)
>  > you end up with: 2 clocks active (2*62.5 > 70), 1 clock recovery
>  > (1*62.5 > 25) and 2 clocks cycle (2*62.5 > 120).
>  > 
>  > Last time I checked, active + recovery must always be equal to the cycle
>  > time, and unless my math is failing me, 2 + 1 does not equal 2.
> 
> Do you mean active + recovery must be less than or equal to the cycle
> time?  Because 70ns + 25ns does not equal 120ns either...

Now that I've had some breakfast, yes.

In any case, active + recovery must never be greater than the cycle time.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/