Re: musb as module broken in 2.6.38

From: Alexander Holler
Date: Wed Mar 16 2011 - 07:21:56 EST

Am 16.03.2011 11:48, schrieb Felipe Balbi:

On Mar 16, 2011, at 12:43 PM, Alexander Holler wrote:

Am 16.03.2011 11:38, schrieb Felipe Balbi:

On Mar 16, 2011, at 12:30 PM, Alexander Holler wrote:
Am 16.03.2011 11:24, schrieb Felipe Balbi:

On Mar 16, 2011, at 12:17 PM, Alexander Holler wrote:
static int __init omap2430_probe(struct platform_device *pdev)

Neither omap2430_init() nor omap2430_probe() will be called here.

and why is that ? It's even in sysfs already:

beagle linux # ls /sys/devices/platform/ | grep musb

Don't know, I haven't written or changed the driver. ;)

hehe, Just thought that you had something in mind already.

probe() functions are called when, in case of platform_devices,
the name matches with driver name. musb-omap2430 platform_device
is allocated in arch/arm/mach-omap2/usb-musb.c, then musb-2430
driver lives in drivers/usb/musb/omap2430.c. musb-2430 allocates a
platform_device for musb-hdrc core driver.

We did that because the same core is used in many different platforms
(OMAP, discrete chips, ST-Ericsson, DaVinci, PCI cards, etc) so we
needed to "abstract" platform-specific details such as clock handling
and power management.

There's still work to be done, for sure, e.g. the DMA part is still quite
screwed up, but the drivers are correctly named which means they
should be matching and probing. Now, musb-hdrc isn't probing, as
you say, and I'd like to know why. I'll try to spend some time in
it when I get back to the office.

I currently assume it's something with


Have to read about subsys_initcall() and why omap2430_init isn't called here.

I guess I know what the problem is. If you search for omap2430_init
in vmlinux it won't be there. I guess when a directory is marked as
obj-m, Kbuild won't search for symbols to be statically linked to vmlinux
on that directory. Since we use the same Kconfig entry to select musb as
module and include drivers/usb/musb directory into build system, we
are falling into that case.

Try changing drivers/usb/musb to obj-y in drivers/Makefile and see if things
start working.

Thanks, seems to be the right way, but doesn't work without more changes. I get some undefined references e.g. to stuff in musb_core.c and musb_debug (otg_state_string and musb_debug). I assume it's because musb_core and musb_debug are part of the module musb_hdrc.


Alexander Holler
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