From: Weifeng Liu <weifeng.liu.z@gmail.com>
To: platform-driver-x86@vger.kernel.org, linux-serial@vger.kernel.org
Cc: Weifeng Liu <weifeng.liu.z@gmail.com>,
Andy Shevchenko <andriy.shevchenko@intel.com>,
Maximilian Luz <luzmaximilian@gmail.com>,
Hans de Goede <hdegoede@redhat.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Subject: [PATCH v3 1/2] platform/surface: aggregator: Defer probing when serdev is not ready
Date: Sun, 5 May 2024 21:07:49 +0800 [thread overview]
Message-ID: <20240505130800.2546640-2-weifeng.liu.z@gmail.com> (raw)
In-Reply-To: <20240505130800.2546640-1-weifeng.liu.z@gmail.com>
This is an attempt to alleviate race conditions in the SAM driver where
essential resources like serial device and GPIO pins are not ready at
the time ssam_serial_hub_probe() is called. Instead of giving up
probing, a better way would be to defer the probing by returning
-EPROBE_DEFER, allowing the kernel try again later.
However, there is no way of identifying all such cases from other real
errors in a few days. So let's take a gradual approach identify and
address these cases as they arise. This commit marks the initial step
in this process.
Suggested-by: Maximilian Luz <luzmaximilian@gmail.com>
Reviewed-by: Maximilian Luz <luzmaximilian@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Weifeng Liu <weifeng.liu.z@gmail.com>
---
drivers/platform/surface/aggregator/core.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/drivers/platform/surface/aggregator/core.c b/drivers/platform/surface/aggregator/core.c
index ba550eaa06fc..7b1871eb7a6f 100644
--- a/drivers/platform/surface/aggregator/core.c
+++ b/drivers/platform/surface/aggregator/core.c
@@ -645,9 +645,22 @@ static int ssam_serial_hub_probe(struct serdev_device *serdev)
/* Set up serdev device. */
serdev_device_set_drvdata(serdev, ctrl);
serdev_device_set_client_ops(serdev, &ssam_serdev_ops);
+
+ /*
+ * The following step can fail when it's called too early before the
+ * underlying UART device is ready (in this case -ENXIO is returned).
+ * Instead of simply giving up and losing everything, we can defer
+ * the probing by returning -EPROBE_DEFER so that the kernel would be
+ * able to retry later.
+ */
status = serdev_device_open(serdev);
- if (status)
+ if (status == -ENXIO)
+ status = -EPROBE_DEFER;
+ if (status) {
+ dev_err_probe(&serdev->dev, status,
+ "failed to open serdev device\n");
goto err_devopen;
+ }
astatus = ssam_serdev_setup_via_acpi(ssh->handle, serdev);
if (ACPI_FAILURE(astatus)) {
--
2.44.0
next prev parent reply other threads:[~2024-05-05 13:08 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-05 13:07 [PATCH v3 0/2] Defer probing of SAM if serdev device is not ready Weifeng Liu
2024-05-05 13:07 ` Weifeng Liu [this message]
2024-05-06 9:06 ` [PATCH v3 1/2] platform/surface: aggregator: Defer probing when serdev " Andy Shevchenko
2024-05-05 13:07 ` [PATCH v3 2/2] platform/surface: aggregator: Log critical errors during SAM probing Weifeng Liu
2024-05-13 11:55 ` Hans de Goede
2024-05-06 14:41 ` [PATCH v3 0/2] Defer probing of SAM if serdev device is not ready Hans de Goede
2024-05-06 14:52 ` Andy Shevchenko
2024-05-07 13:44 ` Weifeng Liu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240505130800.2546640-2-weifeng.liu.z@gmail.com \
--to=weifeng.liu.z@gmail.com \
--cc=andriy.shevchenko@intel.com \
--cc=andriy.shevchenko@linux.intel.com \
--cc=hdegoede@redhat.com \
--cc=linux-serial@vger.kernel.org \
--cc=luzmaximilian@gmail.com \
--cc=platform-driver-x86@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).