[PATCH] coresight-tmc: Add configurable timeout for flush and tmcready

[Leo Yan]

On Fri, Jun 27, 2025 at 12:23:29PM +0100, James Clark wrote:
> 
> 
> On 27/06/2025 12:10 pm, Yuanfang Zhang wrote:
> > The current implementation uses a fixed timeout via
> > coresight_timeout(), which may be insufficient when multiple
> > sources are enabled or under heavy load, leading to TMC
> > readiness or flush completion timeout.
> > 
> > This patch introduces a configurable timeout mechanism for
> > flush and tmcready.
> > 
> 
> What kind of values are you using? Is there a reason to not increase the
> global one?

IIUC, this patch is related to patch [1].

It seems to me that both patches aim to address the long latency when
flushing the TMC, but take different approaches. In the earlier patch,
both Mike and I questioned how the timeout occurred in hardware, but
no information provided about the cause.

I would suggest that we first make clear if this is a hardware quirk or
a common issue in Arm CoreSight.

Thanks,
Leo

[1] https://lore.kernel.org/linux-arm-kernel/CAJ9a7Vgre_3mkXB_xeVx5N9BqPTa2Ai4_8E+daDZ-yAUv44A9g@mail.gmail.com/