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driver core: Make deferred_probe_timeout default a Kconfig option

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Code using driver_deferred_probe_check_state() differs from most
EPROBE_DEFER handling in the kernel. Where other EPROBE_DEFER handling
(e.g. clks, gpios and regulators) waits indefinitely for suppliers to
show up, code using driver_deferred_probe_check_state() will fail
after the deferred_probe_timeout.

This is a problem for generic distro kernels which want to support many
boards using a single kernel build. These kernels want as much drivers to
be modular as possible. The initrd also should be as small as possible,
so the initrd will *not* have drivers not needing to get the rootfs.

Combine this with waiting for a full-disk encryption password in
the initrd and it is pretty much guaranteed that the default 10s timeout
will be hit, causing probe() failures when drivers on the rootfs happen
to get modprobe-d before other rootfs modules providing their suppliers.

Make the default timeout configurable from Kconfig to allow distro kernel
configs where many of the supplier drivers are modules to set the default
through Kconfig.

Reviewed-by: Saravana Kannan <saravanak@kernel.org>
Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Link: https://patch.msgid.link/20260314084916.10868-1-johannes.goede@oss.qualcomm.com
[ Drop deferred_probe_timeout documentation change in
  kernel-parameters.txt. - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
This commit is contained in:
Hans de Goede 2026-03-14 09:49:16 +01:00 committed by Danilo Krummrich
parent 3210dabba4
commit 56e3ee721b
2 changed files with 10 additions and 5 deletions
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9
drivers/base/Kconfig
View File

@ -73,6 +73,15 @@ config DEVTMPFS_SAFE
with the PROT_EXEC flag. This can break, for example, non-KMS
video drivers.
config DRIVER_DEFERRED_PROBE_TIMEOUT
int "Default value for deferred_probe_timeout"
default 0 if !MODULES
default 10 if MODULES
help
Set the default value for the deferred_probe_timeout kernel parameter.
See Documentation/admin-guide/kernel-parameters.txt for a description
of the deferred_probe_timeout kernel parameter.
config STANDALONE
bool "Select only drivers that don't need compile-time external firmware"
default y

6
drivers/base/dd.c
View File

@ -257,11 +257,7 @@ static int deferred_devs_show(struct seq_file *s, void *data)
}
DEFINE_SHOW_ATTRIBUTE(deferred_devs);
#ifdef CONFIG_MODULES
static int driver_deferred_probe_timeout = 10;
#else
static int driver_deferred_probe_timeout;
#endif
static int driver_deferred_probe_timeout = CONFIG_DRIVER_DEFERRED_PROBE_TIMEOUT;
static int __init deferred_probe_timeout_setup(char *str)
{