linux-kernel - Re: [PATCH v2] staging: comedi: resolve section mismatch in s626

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Date:	Tue, 10 Apr 2012 11:24:38 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Ian Abbott <abbotti@....co.uk>
Cc:	"devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
	Gerard Snitselaar <dev@...tselaar.org>,
	Ian Abbott <ian.abbott@....co.uk>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"fmhess@...rs.sourceforge.net" <fmhess@...rs.sourceforge.net>
Subject: Re: [PATCH v2] staging: comedi: resolve section mismatch in s626

On Mon, Apr 02, 2012 at 11:48:54AM +0100, Ian Abbott wrote:
> On 2012-03-19 23:26, Greg KH wrote:
> >On Mon, Mar 19, 2012 at 03:46:49PM -0700, Gerard Snitselaar wrote:
> >>On Mon, Mar 19, 2012 at 09:43:25AM -0700, Gerard Snitselaar wrote:
> >>>On Mon, Mar 19, 2012 at 09:31:03AM -0700, Greg KH wrote:
> >>>>
> >>>>Ick, why is this loop even needed?  We are only here if the pci device
> >>>>is present in the system so this shouldn't be needed at all, right?
> >>>>
> >>>>Or is this a bit more complex than I am making it out to be?
> >>>>
> >>>>greg k-h
> >>>
> >>>Most likely not. I will take a look at some of the other drivers in
> >>>comedi and see how the attach code looks there. I believe the code
> >>>section in hpdi_attach() was written by the same person. Unfortunately
> >>>I don't have a device to actually play around and see what changes are
> >>>doing.
> >>>
> >>
> >>I looked at this a bit more. It looks like they lose visibility to the
> >>pci_dev structure.
> >>
> >>*_probe()
> >>    comedi_pci_auto_config()     pci_dev
> >>       comedi_auto_config()      pci_dev->dev
> >>          comedi_device_attach() ??
> >>             driv->attach()      ??<= iterate through pci devices.
> >>
> >>Most of the examples I have looked at so far use for_each_pci_dev() to
> >>find the device, and s626 shortcuts it a bit by directly making calls
> >>to pci_get_subsys() with specific ids. They all verify they have the
> >>right device by checking the bus and slot that are grabbed from the
> >>pci_dev in comedi_pci_auto_config() and passed down.
> >
> >Ugh, surely there's a way to keep the pci dev through the
> >comedi_device_attach() call, right?
> 
> comedi_device_attach() is also called for the COMEDI_DEVCONFIG ioctl
> for "manually" configuring a comedi device, and that has no idea
> about struct pci_dev, etc.
> 
> I recently posted a series of patches that allows lower-level comedi
> drivers to supply separate hooks for auto-configuring PCI devices or
> USB devices without abusing the old "manual configuration" code
> paths, see <http://driverdev.linuxdriverproject.org/pipermail/devel/2012-March/025331.html>.
> 
> The old loop that searches the PCI bus is still needed for the
> "manual configuration" code path.

So, now that I've applied your patches, this patch isn't needed anymore,
right?  Or should it be reworked to use the new interfaces?

thanks,

greg k-h
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