Re: [PATCH 1/1] V4L/v4l2-dev: Make 'videodev_init' as a subsys initcall

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Bhupesh,

On Monday 12 March 2012 18:13:18 Bhupesh SHARMA wrote:
> On Monday, March 12, 2012 3:35 PM Laurent Pinchart wrote:
> > On Monday 12 March 2012 14:39:02 Bhupesh Sharma wrote:
> > > As the V4L2 based UVC webcam gadget (g_webcam) expects the
> > > 'videodev' to present when the 'webcam_bind' routine is called,
> > > so 'videodev' should be available as early as possible.
> > > 
> > > Now, when 'g_webcam' is built as a module (i.e. not a part of
> > > kernel) the late availability of 'videodev' is OK, but if
> > > 'g_webcam' is built statically as a part of the kernel,
> > > the kernel crashes (a sample crash dump using Designware 2.0 UDC
> > > is provided below).
> > > 
> > > To solve the same, this patch makes 'videodev_init' as a subsys
> > 
> > initcall.
> > 
> > > Kernel Crash Dump:
> > > ------------------
> > 
> > [snip]
> > 
> > > Signed-off-by: Bhupesh Sharma <bhupesh.sharma@st.com>
> > > ---
> > > 
> > >  drivers/media/video/v4l2-dev.c |    2 +-
> > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > > 
> > > diff --git a/drivers/media/video/v4l2-dev.c
> > 
> > b/drivers/media/video/v4l2-dev.c
> > 
> > > index 96e9615..041804b 100644
> > > --- a/drivers/media/video/v4l2-dev.c
> > > +++ b/drivers/media/video/v4l2-dev.c
> > > @@ -788,7 +788,7 @@ static void __exit videodev_exit(void)
> > > 
> > >  	unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
> > >  
> > >  }
> > > 
> > > -module_init(videodev_init)
> > > +subsys_initcall(videodev_init);
> > > 
> > >  module_exit(videodev_exit)
> > >  
> > >  MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab
> > 
> > <mchehab@infradead.org>");
> > 
> > Shouldn't drivers/media/media-devnode.c then use subsys_initcall() as
> > well ?
> 
> Yes, it should. Do you want me to send a patch for the same also?
> 
> But I have no platform to check whether the Media Controller changes
> for g_webcam work on a real platform (i.e. omap3isp), so can you
> kindly test the patch I send for the same on your setup?

I'll test both on the OMAP3 ISP and I'll send a patch for media-devnode.c.

-- 
Regards,

Laurent Pinchart