[PATCH v5] drivers/tty: amba: defer probing DMA availability until hw_init

[Russell King - ARM Linux]

On Tue, Mar 03, 2015 at 10:13:21AM -0600, Rob Herring wrote:
> On Thu, Feb 26, 2015 at 10:56 AM, Jorge Ramirez-Ortiz
> <jorge.ramirez-ortiz at linaro.org> wrote:
> > Fix a race condition that happens when device_initcall(pl011_dma_initicall)
> > is executed before all the devices have been probed - this issue was observed on
> > an hisi_6220 SoC (HiKey board from Linaro).
> >
> > The deferred driver probing framework relies on late_initcall to trigger
> > deferred probes so it is just possible that, even with a valid DMA driver ready
> > to be loaded, we fail to synchronize with it.
> >
> > The proposed implementation delays probing of the DMA until the uart device is
> > opened. As hw_init is invoked on port startup and port resume - but the DMA
> > probe is only required once - we avoid calling multiple times using a new field
> > in uart_amba_port to track this scenario.
> >
> > This commit allows for subsequent attempts to associate an external DMA if the
> > DMA driver was deferred at UART hw_init time.
> >
> > Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz at linaro.org>
> 
> You need to send this to Greg KH and linux-serial if you want it applied.

ARM PRIMECELL UART PL010 AND PL011 DRIVERS
M:      Russell King <linux at arm.linux.org.uk>
S:      Maintained
F:      drivers/tty/serial/amba-pl01*.c
F:      include/linux/amba/serial.h

And you really should wait for _my_ approval and ack, especially as I've
already highlighted concerns in previous replies to the change of DMA
management thing.

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