Hello Sebastian,
Thank you for the clarifications.
We have discussed this internally, and there were two main discussion
points:
1. Users of custom GRLIB+LEON3 systems (FPGA/ASIC) may be affected by
the RTEMS hardware requirement change of needing one more subtimer.
2. The application will have access to one less subtimer. This affects
for example the UT700 LEON3 component.
The conclusion is that we are positive to the change proposed in this
patch. It is also in line with LEON3 hardware requirements for other
operating systems.
After the AMP scenario (see below) has been clarified, this commit is OK.
On 2023-10-13 13:00, Sebastian Huber wrote:
Hello Martin,
On 13.10.23 12:09, Martin Åberg wrote:
What are the implications when using RTEMS_MULTIPROCESSING together
with "use_gptimer"?
In bsps/sparc/leon3/include/bsp/leon3.h, we have:
> #if defined(RTEMS_MULTIPROCESSING)
> #define LEON3_CLOCK_INDEX \
> ( rtems_configuration_get_user_multiprocessing_table() ?
LEON3_Cpu_Index : 0 )
> #else
> #define LEON3_CLOCK_INDEX 0
> #endif
Can LEON3_COUNTER_GPTIMER_INDEX of CPU0 be equal to LEON3_CLOCK_INDEX
of CPU1 here?
The individual RTEMS instances could share the GPTIMER configured in
free-running mode.
LEON3_Timer_Regs is probed in amba.c. There is a link time option to set
GPTIMER core index (leon3_timer_core_index). Instances could have unique
GPTIMER cores associated.
The preprocessor symbols LEON3_CLOCK_INDEX (clock driver) and
LEON3_COUNTER_GPTIMER_INDEX (timecounter) are used as subtimer index of
the GPTIMER core LEON3_Timer_Regs.
For CPU0 these are:
- LEON3_CLOCK_INDEX is 0 (equal to hardware processor index)
- LEON3_COUNTER_GPTIMER_INDEX is 1 (LEON3_CLOCK_INDEX+1)
For CPU1 these are:
- LEON3_CLOCK_INDEX is 1 (equal to hardware processor index)
- LEON3_COUNTER_GPTIMER_INDEX is 2 (LEON3_CLOCK_INDEX+1)
etc...
In the case when LEON3_Timer_Regs is different on CPU0 and CPU1, there
is no conflict but will leave low-numbered subtimers unused. (Behavior
not introduced by this patch.)
In the case when LEON3_Timer_Regs is equal on the CPU0 and CPU1
instances, it appears there is now a conflict between
CPU0:LEON3_COUNTER_GPTIMER_INDEX and CPU1:LEON3_CLOCK_INDEX.
The GR712RC and GR740 do not need the additional GPTIMER subtimer. Which
products would be affected by this change? I hope that all future
Gaisler products provide a free-running counter device with a capture
feature for PPS.
Thank you for the input. I have created an internal ticket on the
free-running counter.
--
Best regards,
Martin Åberg
Software Engineer
Frontgrade Gaisler
martin.ab...@gaisler.com
Frontgrade Gaisler AB, Kungsgatan 12, SE-411 19 GÖTEBORG, Sweden.
+46 (0) 31 775 8650, www.gaisler.com
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