From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: Tushar Behera <tushar.behera@linaro.org>,
linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
linux-samsung-soc@vger.kernel.org, jslaby@suse.cz,
ben.dooks@codethink.co.uk, broonie@kernel.org
Subject: Re: [PATCH 2/2] serial: pl011: Move uart_register_driver call to device probe
Date: Thu, 13 Feb 2014 18:42:49 +0000 [thread overview]
Message-ID: <20140213184249.GC30257@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20140213182701.GA32578@kroah.com>
On Thu, Feb 13, 2014 at 10:27:01AM -0800, Greg KH wrote:
> On Thu, Feb 13, 2014 at 06:15:59PM +0000, Russell King - ARM Linux wrote:
> > On Thu, Feb 13, 2014 at 10:12:16AM -0800, Greg KH wrote:
> > > On Mon, Jan 20, 2014 at 10:04:15AM +0000, Russell King - ARM Linux wrote:
> > > > On Mon, Jan 20, 2014 at 02:32:35PM +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.
> > > >
> > > > NAK. There should not be any other driver using amba-pl011's device numbers.
> > >
> > > I agree, but there is. And because of that, moving the registration to
> > > the probe call fixes the issue with building a kernel with all of the
> > > drivers built into them, so I'm going to take both of these patches, as
> > > it does solve that problem, while still allowing the device number
> > > collision to happen.
> >
> > So what happens when two _devices_ are probed by this driver at the same
> > time?
>
> The bus that the driver is on will not allow that to happen, I thought
> we went through this before...
>
> And yes, devices on different busses could cause problems, but is that
> the case here for these devices? At first glance, I don't think that
> can happen for these drivers.
We went through this before, and I stated the paths, and no one disagreed
with that.
It /is/ racy.
--
FTTC broadband for 0.8mile line: 5.8Mbps down 500kbps up. Estimation
in database were 13.1 to 19Mbit for a good line, about 7.5+ for a bad.
Estimate before purchase was "up to 13.2Mbit".
next prev parent reply other threads:[~2014-02-13 18:42 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-20 9:02 [PATCH 0/2] serial: Move uart_register_driver call to device probe Tushar Behera
2014-01-20 9:02 ` [PATCH 1/2] serial: samsung: " Tushar Behera
2014-01-20 10:05 ` Russell King - ARM Linux
2014-01-20 11:53 ` Tushar Behera
2014-01-20 12:26 ` Russell King - ARM Linux
2014-01-20 21:43 ` Alan Cox
2014-01-20 23:14 ` Mark Brown
2014-01-20 23:21 ` Russell King - ARM Linux
2014-01-20 23:35 ` Alan Cox
2014-01-20 23:52 ` Greg Kroah-Hartman
2014-01-20 23:47 ` Alan Cox
2014-01-21 0:16 ` Russell King - ARM Linux
2014-01-21 9:03 ` Alan Cox
2014-01-21 9:49 ` Russell King - ARM Linux
[not found] ` <50b66ac6-1150-4ad7-aeaf-3d0dce77334d@email.android.com>
2014-01-26 11:54 ` Russell King - ARM Linux
2014-01-27 4:30 ` Nicolas Pitre
2014-01-27 10:07 ` Alan Cox
2014-01-27 12:32 ` Russell King - ARM Linux
2014-01-27 15:03 ` Nicolas Pitre
2014-01-21 16:59 ` Mark Brown
2014-01-21 18:30 ` Russell King - ARM Linux
2014-01-23 18:04 ` Alan Cox
2014-01-23 18:40 ` Mark Brown
2014-01-23 18:47 ` Tomasz Figa
2014-01-23 19:36 ` Mark Brown
2014-01-23 19:51 ` Alan Cox
2014-01-23 20:05 ` Mark Brown
2014-01-23 21:33 ` Alan Cox
2014-01-24 12:03 ` Mark Brown
2014-01-24 14:38 ` Alan Cox
2014-01-27 0:15 ` Mark Brown
2014-01-26 21:09 ` Pavel Machek
2014-01-27 0:04 ` Alan Cox
2014-01-20 21:16 ` Greg KH
2014-01-20 21:32 ` Russell King - ARM Linux
2014-01-20 23:11 ` Greg KH
2014-01-20 23:16 ` Russell King - ARM Linux
2014-01-20 23:51 ` Greg KH
2014-01-21 0:07 ` Russell King - ARM Linux
2014-01-21 0:26 ` Greg KH
2014-01-21 0:38 ` Russell King - ARM Linux
2014-01-21 9:25 ` One Thousand Gnomes
2014-01-21 9:45 ` Russell King - ARM Linux
2014-01-20 9:02 ` [PATCH 2/2] serial: pl011: " Tushar Behera
2014-01-20 10:04 ` Russell King - ARM Linux
2014-02-13 18:12 ` Greg KH
2014-02-13 18:15 ` Russell King - ARM Linux
2014-02-13 18:27 ` Greg KH
2014-02-13 18:42 ` Russell King - ARM Linux [this message]
2014-02-13 23:26 ` Greg KH
2014-02-14 0:07 ` Russell King - ARM Linux
2014-02-14 0:14 ` Greg KH
2014-02-14 0:38 ` Russell King - ARM Linux
2014-02-17 15:35 ` One Thousand Gnomes
2014-02-17 15:54 ` One Thousand Gnomes
2014-02-17 23:50 ` Mark Brown
2014-02-18 10:09 ` Etched Pixels
2014-02-19 13:57 ` Mark Brown
2014-02-19 14:47 ` One Thousand Gnomes
2014-02-19 15:53 ` Mark Brown
2014-02-19 0:47 ` One Thousand Gnomes
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