On 08/15/2016 09:48 AM, Alexander Graf wrote:
On the raspberry pi, you can disable the serial port to gain dynamic frequency
scaling which can get handy at times.
However, in such a configuration the serial controller gets its rx queue filled
up with zero bytes which then happily get transmitted on to whoever calls
getc() today.
This patch adds detection logic for that case by checking whether the RX pin is
mapped to GPIO15 and disables the mini uart if it is not mapped properly.
That way we can leave the driver enabled in the tree and can determine during
runtime whether serial is usable or not, having a single binary that allows for
uart and non-uart operation.
Acked-by: Stephen Warren <swar...@wwwdotorg.org>
Nits:
I'd hope for a core DM feature to disable statically created devices
rather than re-implementing it per driver, so we don't have to re-invent
this each time we need it. Still, we can refactor this later if it turns
out to be more generally useful.
Perhaps a separate patch for the raw serial driver feature
(serial_bcm283x_mu.h, serial_bcm283x_mu.c), and the board-specific logic
(all the other files)?
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