Re: [PATCH 1/2] serial: samsung: Move uart_register_driver call todevice probe
From: Greg KH
Date: Mon Jan 20 2014 - 16:15:22 EST
On Mon, Jan 20, 2014 at 10:05:30AM +0000, Russell King - ARM Linux wrote:
> On Mon, Jan 20, 2014 at 02:32:34PM +0530, Tushar Behera wrote:
> > uart_register_driver call binds the driver to a specific device
> > node through tty_register_driver call. This should typically happen
> > during device probe call.
> > In a multiplatform scenario, it is possible that multiple serial
> > drivers are part of the kernel. Currently the driver registration fails
> > if multiple serial drivers with same default major/minor numbers are
> > included in the kernel.
> > A typical case is observed with amba-pl011 and samsung-uart drivers.
> The samsung-uart driver is at fault here - the major/minor numbers were
> officially registered to amba-pl011. Samsung needs to be fixed properly.
I agree, the Samsung driver is "broken" here, but that's no reason why
these two drivers can't register with the tty layer _after_ the hardware
is detected, and not before.
That saves resources on systems that build the drivers in, yet do not
have the hardware present, which is always a good thing.
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