linux-kernel - [PATCH] drivers: core: Clarify EPROBE

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Message-Id: <20241105045535.84071-1-yesanishhere@gmail.com>
Date: Mon,  4 Nov 2024 20:55:35 -0800
From: anish kumar <yesanishhere@...il.com>
To: corbet@....net
Cc: linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org,
	anish kumar <yesanishhere@...il.com>
Subject: [PATCH] drivers: core: Clarify EPROBE_DEFER retry mechanism

The existing documentation for EPROBE_DEFER explains its purpose
and usage, but does not specify when deferred probes are retried.
This patch adds information about the retry mechanism to provide
a more complete explanation of how EPROBE_DEFER works.

Specifically, it clarifies that:

1. Deferred probes are added to a pending list
2. A successful probe of any device triggers moving all devices
   from the pending list to an active list
3. A workqueue processes the active list to retry deferred probes

This additional context helps developers better understand the
behavior and implications of using EPROBE_DEFER in their drivers.

Signed-off-by: anish kumar <yesanishhere@...il.com>
---
 Documentation/driver-api/driver-model/driver.rst | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/Documentation/driver-api/driver-model/driver.rst b/Documentation/driver-api/driver-model/driver.rst
index 06f818b1d622..c86b948d0dfe 100644
--- a/Documentation/driver-api/driver-model/driver.rst
+++ b/Documentation/driver-api/driver-model/driver.rst
@@ -171,10 +171,13 @@ released all resources it allocated.
 Optionally, probe() may return -EPROBE_DEFER if the driver depends on
 resources that are not yet available (e.g., supplied by a driver that
 hasn't initialized yet).  The driver core will put the device onto the
-deferred probe list and will try to call it again later. If a driver
-must defer, it should return -EPROBE_DEFER as early as possible to
-reduce the amount of time spent on setup work that will need to be
-unwound and reexecuted at a later time.
+deferred probe list and will retry again as and when a device or driver
+gets added to the system. A successful probe of any device will trigger
+moving all devices from pending list to active list. A workqueue processes
+the active list to retry deferred probes. If a driver must defer, it
+should return -EPROBE_DEFER as early as possible to reduce the amount
+of time spent on setup work that will need to be unwound and reexecuted
+at a later time.
 
 .. warning::
       -EPROBE_DEFER must not be returned if probe() has already created
-- 
2.39.3 (Apple Git-146)