From: Leo Yan <leo.yan@arm.com>
To: Jie Gan <jie.gan@oss.qualcomm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>,
Mike Leach <mike.leach@arm.com>,
James Clark <james.clark@linaro.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Tingwei Zhang <tingwei.zhang@oss.qualcomm.com>,
coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] coresight: platform: check the availability of the endpoint before parse
Date: Fri, 20 Mar 2026 08:25:49 +0000 [thread overview]
Message-ID: <20260320082549.GO8048@e132581.arm.com> (raw)
In-Reply-To: <20260320-add-availability-check-v1-1-b2e39cdeb6e0@oss.qualcomm.com>
On Fri, Mar 20, 2026 at 03:31:12PM +0800, Jie Gan wrote:
> Check endpoint availability before parsing it. If parsing a connected
> endpoint fails, the probe is deferred until the endpoint becomes
> available, or eventually fails.
I want to clarify a bit the failure flow.
Does this mean coresight_find_device_by_fwnode() returns NULL when the
remote device is not found, resulting in -EPROBE_DEFER, but the probe
never waits for the remote device to become available?
> In some legacy cases, a replicator
> has two output ports where one is disabled and the other is available.
> The replicator probe always fails because the disabled endpoint never
> becomes available for parsing. In addition, there is no need to defer
> probing a device that is connected to a disabled device, which improves
> probe performance.
>
> Signed-off-by: Jie Gan <jie.gan@oss.qualcomm.com>
> ---
> drivers/hwtracing/coresight/coresight-platform.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c
> index 0ca3bd762454..e337b6e2bf32 100644
> --- a/drivers/hwtracing/coresight/coresight-platform.c
> +++ b/drivers/hwtracing/coresight/coresight-platform.c
> @@ -220,6 +220,8 @@ static int of_coresight_parse_endpoint(struct device *dev,
> rparent = of_coresight_get_port_parent(rep);
> if (!rparent)
> break;
> + if (!of_device_is_available(rparent))
> + break;
> if (of_graph_parse_endpoint(rep, &rendpoint))
> break;
>
>
> ---
> base-commit: b5d083a3ed1e2798396d5e491432e887da8d4a06
> change-id: 20260320-add-availability-check-4cb2ee6e520b
>
> Best regards,
> --
> Jie Gan <jie.gan@oss.qualcomm.com>
>
next prev parent reply other threads:[~2026-03-20 8:26 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-20 7:31 [PATCH] coresight: platform: check the availability of the endpoint before parse Jie Gan
2026-03-20 8:25 ` Leo Yan [this message]
2026-03-20 8:44 ` Jie Gan
2026-03-20 9:23 ` Leo Yan
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