[PATCH 3/4] serial: bcm2835: add auxiliary uart1 to device tree of bcm2835

Martin Sperl kernel at martin.sperl.org
Wed Sep 23 03:01:50 PDT 2015

On 22.09.2015 04:42, Stephen Warren wrote:
> On 09/11/2015 05:20 AM, kernel at martin.sperl.org wrote:
>> From: Martin Sperl <kernel at martin.sperl.org>
>> Add the auxiliary uart1 device to the device tree of the bcm2835 SOC.
>> diff --git a/arch/arm/boot/dts/bcm2835.dtsi b/arch/arm/boot/dts/bcm2835.dtsi
>> +		uart1: uart at 7e215040 {
>> +			compatible = "ns16550";
> compatible should always include a precise HW-specific value; something
> like brcm,bcm2835-aux-uart. That way, if we find some other issue that
> needs working around on this HW in the future, all DTs will already
> contain the compatible value that SW needs in order to trigger that
> workaround. That's a generally true statement; i.e. irrespective of
> anything else in this series.
> I don't believe "ns16550" should be in the compatible value for this
> device, since the device cannot be successfully driven by SW that only
> knows about a standard 16650 UART. SW must know about the different
> divider, and there is no possibility of SW knowing about that before
> this series.

OK - I will look into creating a separate driver then that uses the 8250
implementation as a basis...

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