linux-kernel - Issue with iwlwifi Firmware Loading When Compiled into the Kernel

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Message-ID: <tencent_2C31282B61589DFCC908B3831384D569440A@qq.com>
Date: Thu, 31 Oct 2024 09:46:20 +0800
From: Gang Yan <gang_yan@...mail.com>
To: Miri Korenblit <miriam.rachel.korenblit@...el.com>,
	Kalle Valo <kvalo@...nel.org>
Cc: linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Issue with iwlwifi Firmware Loading When Compiled into the Kernel

Dear Maintainer,

Recently, I met an issue that I would like to bring to your attention and 
seek your expertise on.

When I compile the iwlwifi driver directly into the kernel by setting 
[CONFIG_IWLWIFI=y], I encounter an error message stating, "iwlwifi direct 
firmware load for iwlwifi-so-XXXX failed." However, the relevant firmware 
files are present in the /lib/firmware directory.

Based on my observations, I suspect that when iwlwifi is compiled into the 
kernel, it attempts to load the firmware before the /lib/firmware directory
mounted. Consequently, the firmware cannot be found. Once the filesystem is
 mounted, iwlwifi does not attempt to reload the firmware.

To address this issue, I have considered two potential solutions:

1、Modify the Driver Code: Implement a mechanism, such as delayed_work, to 
give iwlwifi another chance to load the firmware after the filesystem has 
been mounted. This would involve adding additional logic to the driver to 
handle retries for firmware loading.

2、Modify the Kconfig: Change the configuration to allow iwlwifi to be 
compiled only as a module [CONFIG_IWLWIFI=m]. This way, the module can be 
loaded after the filesystem is fully mounted, ensuring that the firmware
 can be found and loaded successfully.

>From my perspective, unless there are compelling reasons to pursue the first
option, I would recommend implementing the second solution. It seems more 
straightforward and avoids potential complications that might arise from 
modifying the driver's core functionality.

I would greatly appreciate your insights on whether my understanding of the
issue is correct and whether such modifications are deemed necessary. 

Thank you for your time and consideration.

Best regards,

Gang Yan