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From:   Yabin Cui <yabinc@google.com>
Date:   Thu, 2 Feb 2023 12:54:29 -0800
Message-ID: <CALJ9ZPNrF-HhUNskr=_MJ1CrnO+0xzSN8pMpER3FMqf5Pd0idg@mail.gmail.com>
Subject: Re: [PATCH v2] coresight: tmc: Don't enable TMC when it's not ready.
To:     Suzuki K Poulose <suzuki.poulose@arm.com>
Cc:     Mike Leach <mike.leach@linaro.org>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Leo Yan <leo.yan@linaro.org>,
        James Clark <james.clark@arm.com>, coresight@lists.linaro.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
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Hi,

> > There is a similar unprepare function in ETR - this should have similar updates.

Thanks for reminding me! I will update the patch to fix it.

> > The tmc_flush_and_stop() function also calls tmc_wait_for_tmcready().
>
> I think this already an error message there, when it fails to complete
> the flush.I thought of adding a WARN_ON, but thought it is not worth much.

I can see error messages when tmc flush timeouts or tmcready timeouts.
I don't know how the callers (read_buffer and disable) can handle this error.
I think the perf event call chain doesn't accept failures when
disabling coresight
devices. So I feel reporting the error is the best effort we can do.

Thanks,
Yabin