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SubjectRe: [PATCH v2] staging: comedi: resolve section mismatch in s626
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.

--
-=( Ian Abbott @ MEV Ltd. E-mail: <abbotti@mev.co.uk> )=-
-=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=-


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