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

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On 09/23/2015 04:01 AM, Martin Sperl wrote:
On 22.09.2015 04:42, Stephen Warren wrote:
On 09/11/2015 05:20 AM, kernel@xxxxxxxxxxxxxxxx wrote:
From: Martin Sperl <kernel@xxxxxxxxxxxxxxxx>

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@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...

I expect all you need to do is add a new PORT_* value to the existing driver (which then drives some new quirk setting re: the clock rate), and add new entry for the compatible value in of_platform_serial_table[] in drivers/tty/serial/of_serial.c to select the correct TYPE_*.
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