2008-04-18 09:01:44     [HELP] Add device driver problem in 08R1-RC8

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2008-04-18 09:01:44     [HELP] Add device driver problem in 08R1-RC8

Qiang HE (CHINA)

Message: 54480   

 

Dear all,

 

We upgrade our device driver for a FT245BL chip from uClinux-dist 2007R1-RC3 to 2008R1-RC8, the steps are the same, but the driver can't be opened.

 

The device is named 'ft245bl', it's a char device. The function xxx_init() is called in the booting progress with no problem, but after booted, there is no /dev/ft235bl in the /dev folder, and when we open it, it just return a -1, and the function xxx_open is not called.

 

In the file:

 

uClinux-dist/vendors/AnalogDevices/BF533-EZKIT/device_table.txt

 

we added a line:

 

/dev/ft245bl c 664 0 0 253 0 0 0 -

 

When in the 2007R1, a device name /dev/ft245bl appears no matter the driver is installed or not, but in 2008R1, it just don't appear.

 

What can we do?

 

Thanks.

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2008-04-18 13:20:57     Re: [HELP] Add device driver problem in 08R1-RC8

Robin Getz (UNITED STATES)

Message: 54495    Qiang:

 

in 2008 (and future) releases, we have move to mdev - dynamic population of the /dev filesystem - it no longer uses the device_table.txt file.

 

-Robin

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2008-04-18 14:03:03     Re: [HELP] Add device driver problem in 08R1-RC8

Mike Frysinger (UNITED STATES)

Message: 54501    we moved to mdev, not udev

 

we default to dynamic device node creation ... if you want static device node creation, you have to make the selection yourself in the user/vendor configuration menu

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2008-04-18 20:37:57     Re: [HELP] Add device driver problem in 08R1-RC8

Qiang HE (CHINA)

Message: 54513    Thanks, is there any documnent about this change?

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2008-04-18 20:51:05     Re: [HELP] Add device driver problem in 08R1-RC8

Mike Frysinger (UNITED STATES)

Message: 54514    in the release notes i imagine

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2008-04-18 22:08:59     Re: [HELP] Add device driver problem in 08R1-RC8

Qiang HE (CHINA)

Message: 54515   

 

The release note just says:

57.Enable mdev daemon to create proper dynamic device inode.

But it doesn't mention the device_table.txt.

 

I don't know how to use mdev, do you mean I can use 'make xconfig" to make some configuration to distable/ignore mdev and use the device_table.txt to set up driver nodes? If not, how to use mdev to set up driver nodes?

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2008-04-18 22:57:03     Re: [HELP] Add device driver problem in 08R1-RC8

Mike Frysinger (UNITED STATES)

Message: 54516    mdev doesnt do anything magical.  if your device driver is written properly, it will trigger the right hotplug events which will automatically call mdev which will automatically create the device nodes.

 

if you're having trouble writing a character device, there are plenty of examples in the tree ... or you can read the relevant chapters in the linux device drivers book.

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2008-04-18 23:12:48     Re: [HELP] Add device driver problem in 08R1-RC8

Qiang HE (CHINA)

Message: 54517   

 

The driver works just fine in dist 2007, it was written following the example driver in the uClinux online help. I just can't understand what's different between 07 and 08.

 

BTW, the register_chrdev function returns a '0', is it normal? In 2007, it returns '0' too, but the driver works, /dev/ft235bl apears.

 

I'm not in my office and can't make any test now.

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2008-04-18 23:36:26     Re: [HELP] Add device driver problem in 08R1-RC8

Mike Frysinger (UNITED STATES)

Message: 54518    2007R1 used static device nodes by default ... thus it wouldnt have "appeared", it would have always been there when you edited the device table.

 

if you want to know about proper character device driver writing, read LDD3 like i already said.  they devote whole chapters to the topic.

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