On 02/19/2012 07:40 PM, Larry Finger wrote:
I sent a previous messages to most of these lists, but got no answer, thus a second try. When a driver loads firmware synchronously in the module_init() path using request_firmware(), then there is trouble with timeouts when booting. I know that changing the request_firmware() call to request_firmware_nowait() solves the problem; however, that gives some trouble for driver b43legacy as it loads 3 or 4 firmware files depending on the hardware version. When I launch the 3 or 4 nowait requests, I get an error because the system is trying to start several tasks with the same name.
Yep, the nowait api just kicks off a kernel thread for the firmware request.
Would it be OK to load the first file with the nowait version, and issue a request_firmware() for the others from the callback routine? I think that would not cause any problems, but I would like to get confirmation from an expert.
No expert, but that is what I did although the chaining of firmware requests does not feel great. Especially for handling error flows. Johannes Berg and Kay Sievers mentioned need to unbind/rebind the driver upon failed firmware load, but I don't like the idea of building a timer-controlled retry mechanism.
Similarly, if I were to create a work queue, init and schedule it from module_init(), and then use synchronous loads to get the firmware from the work queue callback, would that get around the boot problem? I know it works as I have trial patches; however, my version of udev is not one affected. This method is very easy to implement, but again I would like confirmation from an expert.
What boot problem are you referring to? The blocking modprobe? For that problem I would say yes. Also here the problem of handling error flows exist. If the driver is kicked of during boot with a initramfs missing the firmware, should we retry until the real root is mounted?
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