Hi Bill,
On 28/05/11 00:23, J. William Campbell wrote:
On 5/27/2011 12:35 AM, Graeme Russ wrote:
Hi Wolfgang,
On 27/05/11 17:13, Wolfgang Denk wrote:
Dear Graeme Russ,
In messageBANLkTinWvY9b4QzeLNawF7MKT9z1zeMXyg@mail.gmail.com you wrote:
I think we will need to define get_timer() weak - Nios will have to override the default implementation to cater for it's (Nios') limitations
Please don't - isn't the purpose of this whole discussion to use common code for this ?
Yes, but Nios is particularly bad - It has a 10ms tick counter :(
Hi All, And a hardware timer that you can't read to subdivide the 10 ms. Note that this is not necessarily a problem with all NIOS implementations. The timer characteristics can be controlled when you generate the bitstream for the FPGA. You can make the counter both faster and readable if you want. It just uses a bit more silicon. Sad to say, it probably will require per board get_ticks routine. For the "old" nios2 timers however, overriding get_timer with a /board routine is probably the only way to go.
Actually, using the logic you presented in the "Remove calls to [get,reset]_timer outside arch/" thread, we could have a common get_timer() implementation which deals with all timer resolution issues:
#if !defined(CONFIG_MIN_TIMER_RESOLUTION) #define CONFIG_MIN_TIMER_RESOLUTION 1 #endif
u32 get_timer(u32 base) { if (base != 0) { if (timer - base < (CONFIG_MIN_TIMER_RESOLUTION * 2)) return 0; else return timer - base - CONFIG_MIN_TIMER_RESOLUTION; } else { return timer; } }
This would also guarantee that timeout loops run for _at least_ the timeout period
Regards,
Graeme