[Linux-stm32] [RFC] Add trig_ts function in STM to generate TRIG_TS packet periodically

[Suzuki K Poulose]

On 21/02/2023 06:53, Jinlong Mao wrote:
> Hi all,
> 
> When there is some small packet sent from STM to ETR, the small packet 
> could be stuck between source
> and sink even if manual flush is set when disable ETR.

Why ? The manual flush should trigger a flush request upstream
and eventually cause a flush ? If this doesn't work as expected
we should try to get to the bottom of that first, before jumping
into "software work arounds".

> So there is requirement that flush the STM trace periodically after 
> enabling STM to ETR.
> 
> STM can generate TRIG_TS packet by writing to offset 0xF0 of the driver 
> STM stimulus port.
> ETR has ability to initiate a flush on seeing a TRIG_TS packet.

Why is this different from the "manual flush" and how does it help ?
Is it because one of the components doesn't respond properly to the
flush request ?


Kind regards
Suzuki

> 
> For this requirement, I want to create a sysfs node like trig_ts for STM.
> When writing 1 to this sysfs node, a timer with 1 second periodicity in 
> STM will start to generate the trig_ts packet to ETR.
> Once ETR receive the TRIG_TS packet, it will initiate a flush.
> 
> Could you please help to provide your comments on this requirement ?
> 
> Thanks
> Jinlong Mao
>