[PATCH] amba-pl011: support hardware flow control

[Russell King - ARM Linux]

On Wed, Feb 10, 2010 at 01:16:37AM +0000, Jamie Lokier wrote:
> Russell King - ARM Linux wrote:
> > This means that when the kernel's buffers fill up, the kernel calls
> > down to the serial core layer to throttle the input.  This then
> > calls into the set_mctrl function to de-assert RTS.  However, because
> > the hardware ignores the requested software state, the RTS signal
> > is not de-asserted, and the remote end continues sending data.
> > 
> > So, enabling hardware auto-RTS is bad news - you will lose data if
> > the application stops reading data.
> 
> Surely the driver can just stop reading from the UART when the
> kernel's buffers are full and hardware-RTS is enabled.  Then the
> hardware will deassert RTS itself.

I'll let you work out how to implement that.