Re: [RFC PATCH 1/2] serial: 8250: Add a notifier chain for driverregistration.

From: David Daney
Date: Thu Mar 17 2011 - 14:42:30 EST

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@xxxxxxxxxxxxxxxxxx> wrote:

The 8250 driver is a bit weird in that in addition to supporting
platform devices, extra devices can be added by calling

The problem is that if we call serial8250_register_port() before the
driver is initialized Bad Things happen (we dereference NULL

There doesn't seem to be a general way to know if a driver has been

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.


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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