Messages in this thread | | | Date | Thu, 17 Mar 2011 11:42:19 -0700 | From | David Daney <> | Subject | Re: [RFC PATCH 1/2] serial: 8250: Add a notifier chain for driver registration. |
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On 03/17/2011 11:25 AM, Grant Likely wrote: > On Thu, Mar 17, 2011 at 12:18:49PM +0000, Alan Cox wrote: >> On Wed, 16 Mar 2011 18:26:06 -0700 >> David Daney<ddaney@caviumnetworks.com> wrote: >> >>> The 8250 driver is a bit weird in that in addition to supporting >>> platform devices, extra devices can be added by calling >>> serial8250_register_port(). >>> >>> The problem is that if we call serial8250_register_port() before the >>> driver is initialized Bad Things happen (we dereference NULL >>> pointers). >>> >>> There doesn't seem to be a general way to know if a driver has been >>> initialized >> >> I've had a bigger dig into this. I think the correct answer is probably >> "always go via platform devices or similar". That *is* the notifier in >> the kernel of today. serial8250_register_port ultimately should I think >> ultimatly become an internal helper. > > +1 > > Depending on serial8250_register_port() definitely the wrong thing to > do for platform support code. It would be better to figure out how to > get the dt bits you need into 8250.c or of_serial.c. >
IMHO, of_serial.c is no better than my board/chip specific code that calls serial8250_register_port().
Really what would be ideal would be a hook to add a dev.platform_data pointer to the appropriate struct plat_serial8250_port when the platform device is created. It is possible that the platform bus notifiers could be used for this. We would also want to have a way to add an of_device_id to those recognized by 8250.c
If we did that, serial8250_probe() would automatically do the right thing.
David Daney
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