linux-kernel - RE: [PATCH] staging: comedi: remove this

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Message-ID: <ADE657CA350FB648AAC2C43247A983F0020698BAC8D8@AUSP01VMBX24.collaborationhost.net>
Date:	Wed, 23 May 2012 11:28:32 -0500
From:	H Hartley Sweeten <hartleys@...ionengravers.com>
To:	Ian Abbott <abbotti@....co.uk>,
	Dan Carpenter <dan.carpenter@...cle.com>
CC:	Linux Kernel <linux-kernel@...r.kernel.org>,
	"devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
	"fmhess@...rs.sourceforge.net" <fmhess@...rs.sourceforge.net>,
	Ian Abbott <ian.abbott@....co.uk>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
Subject: RE: [PATCH] staging: comedi: remove this_board macro in the s526
 driver

On Wednesday, May 23, 2012 2:18 AM, Ian Abbott wrote:
> On 2012-05-23 06:48, Dan Carpenter wrote:
>> On Tue, May 22, 2012 at 06:20:10PM -0700, H Hartley Sweeten wrote:
>>> -/*
>>> - * Initialize dev->board_name.  Note that we can use the "thisboard"
>>> - * macro now, since we just initialized it in the last line.
>>> - */
>>> -	dev->board_ptr =&s526_boards[0];
>>
>> Was this intended?  Most of the boards have auto probing so the
>> ->board_ptr gets set automatically.  We already called
>> comedi_board() so I wonder if the autoprobed board is the same as
>> the&s526_boards[0];?  NULL pointer perhaps?  I don't know.
>
> If .num_names in struct comedi_driver is non-zero, the core comedi 
> module will set dev->board_ptr to something non-NULL and meaningful to 
> the driver before it calls the driver's ->attach() method.  (This is 
> done by the comedi_recognize() function.)  The driver can change 
> dev->board_ptr to something else if it wants.  In this case, 
> dev->board_ptr will already be set to &s526_boards[0] so there is no 
> point setting it again.

Ian,

Side-note on the boardinfo stuff.

I wonder if it makes sense to create a common boardinfo struct
and modify the comedi_driver struct a bit. Something like:

struct comedi_boardinfo {
	const char *name;
	unsigned short	vendor;
	unsigned short device;
	void *private;
};

struct comedi_driver {
	struct comedi_driver *next;

	const char *driver_name;
	struct module *module;
	int (*attach) (struct comedi_device *, struct comedi_devconfig *);
	void (*detach) (struct comedi_device *);
	int (*attach_pci) (struct comedi_device *, struct pci_dev *);
	int (*attach_usb) (struct comedi_device *, struct usb_interface *);

	u32 num_boards;
	struct comedi_boardinfo *board;
};

This would allow comedi_recognize() to walk the boardinfo
to find the match without all the ugly casts. It should also
allow creating a common comedi_find_pcidev() for all the
comedi pci drivers to use when probing for the board_ptr.

This would create a bit of churn but I think it would be a
lot cleaner in the end.

What do you think?

Regards,
Hartley


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