Date: Sun, 22 Dec 2013 15:09:48 -0200
From: Mauro Carvalho Chehab <m.chehab@samsung.com>
To: Antti Palosaari <crope@iki.fi>
Cc: LMML <linux-media@vger.kernel.org>,
	Frank =?UTF-8?B?U2Now6RmZXI=?= <fschaefer.oss@googlemail.com>
Subject: Re: em28xx list_add corruption reported by list debug
Message-id: <20131222150948.2c894a3b@samsung.com>
In-reply-to: <52B710AE.2070606@iki.fi>
References: <52B615C9.8040806@iki.fi> <20131222130600.652f468a@samsung.com>
 <20131222135531.6af60f77@samsung.com> <52B710AE.2070606@iki.fi>
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Em Sun, 22 Dec 2013 18:17:50 +0200
Antti Palosaari <crope@iki.fi> escreveu:

> On 22.12.2013 17:55, Mauro Carvalho Chehab wrote:
> > Em Sun, 22 Dec 2013 13:06:00 -0200
> > Mauro Carvalho Chehab <m.chehab@samsung.com> escreveu:
> >
> >> Em Sun, 22 Dec 2013 00:27:21 +0200
> >> Antti Palosaari <crope@iki.fi> escreveu:
> >>
> >>> I ran also this kind of bug. Device was PCTV 290e, which has that video
> >>> unused. I have no any analog em28xx webcam to test if that happens here too.
> >>>
> >>> Fortunately I found one video device which does not crash nor dump debug
> >>> bug warnings. It is some old gspca webcam. Have to look example how
> >>> those videobuf callbacks are implemented there..
> >>>
> >>> regards
> >>> Antti
> >>>
> >>>
> >>> [crope@localhost linux]$ cat /dev/video0
> >>> cat: /dev/video0: Invalid argument
> >>> [crope@localhost linux]$ cat /dev/video0
> >>> cat: /dev/video0: Device or resource busy
> >>> [crope@localhost linux]$
> >>>
> >>>
> >>> joulu 22 00:08:24 localhost.localdomain kernel: em28174 #0: no endpoint
> >>> for analog mode and transfer type 0
> >>
> >> It seems that there's something bad on em28174 registration: it should not
> >> be creating a v4l2 device, if the device is DVB only.
> >>
> >> The thing is that, when this driver was created, all devices were either
> >> analog only or hybrid. Only very recently, pure DVB devices got added.
> >>
> >> It shouldn't be that hard to split em28xx_init_dev() into a few routines
> >> that would only register v4l2 if the device has analog support.
> >>
> >> Again, this changeset:
> >> 	https://patchwork.linuxtv.org/patch/17967/
> >>
> >> Seems to be part of such solution, as it already splits the v4l2
> >> register logic into a separate function.
> >
> > Ok, if I didn't make any mistake, this changeset should do the trick:
> > 	https://patchwork.linuxtv.org/patch/21282/
> >
> > Please notice that this is compile-tested only.
> 
> I started to testing that patch, but now I get following compilation 
> errors:
> 
> WARNING: "em28xx_detect_sensor" [drivers/media/usb/em28xx/em28xx.ko] 
> undefined!
> WARNING: "em28xx_init_camera" [drivers/media/usb/em28xx/em28xx.ko] 
> undefined!
> WARNING: "em28xx_resolution_set" 
> [drivers/media/usb/em28xx/em28xx-v4l.ko] undefined!
> WARNING: "em28xx_colorlevels_set_default" 
> [drivers/media/usb/em28xx/em28xx-v4l.ko] undefined!
> WARNING: "em28xx_set_outfmt" [drivers/media/usb/em28xx/em28xx-v4l.ko] 
> undefined!
> WARNING: "em28xx_read_reg_req_len" 
> [drivers/media/usb/em28xx/em28xx-v4l.ko] undefined!
> WARNING: "em28xx_wake_i2c" [drivers/media/usb/em28xx/em28xx-v4l.ko] 
> undefined!
> WARNING: "em28xx_set_alternate" [drivers/media/usb/em28xx/em28xx-v4l.ko] 
> undefined!
> WARNING: "em28xx_vbi_supported" [drivers/media/usb/em28xx/em28xx-v4l.ko] 
> undefined!
> WARNING: "em28xx_release_resources" 
> [drivers/media/usb/em28xx/em28xx-v4l.ko] undefined!
> WARNING: "em28xx_boards" [drivers/media/usb/em28xx/em28xx-v4l.ko] undefined!
> 
> anyhow, I am not sure if those are related or not. I will re-compile 
> whole kernel to see (build only media).


That's the lack of exporting symbols or moving the code. I'm currently
working on testing this patchset.

> 
> regards
> Antti
> 


-- 

Cheers,
Mauro