Re: [PATCH v8 1/2] Serial: silabs si4455 serial driver

On Tue, Jan 12, 2021 at 03:43:22PM +0000, József Horváth wrote:

On Tue, Jan 12, 2021 at 11:28:08AM +0100, 'Greg Kroah-Hartman' wrote:

quoted

On Tue, Jan 12, 2021 at 10:18:33AM +0000, Jozsef Horvath wrote:

quoted

--- a/include/uapi/linux/serial_core.h
+++ b/include/uapi/linux/serial_core.h

@@ -279,4 +279,7 @@
 /* Freescale LINFlexD UART */
 #define PORT_LINFLEXUART	122
 
+/* Silicon Labs SI4455 */
+#define PORT_SI4455     123

What userspace tool is going to need this value?

The PORT_SI4455 is defined for using as port type value in struct uart_port.
I checked other serial drivers under drivers/tty/serial and the port types
used by serial drivers are defined in two places:

include/uapi/linux/serial_core.h
include/uapi/linux/serial.h

The port type is required by serial_core, and its value goes back to
user space with TIOCGSERIAL ioctl call.

What is it required for?  Who uses this?

I can't set port type value to 0(PORT_UNKNOWN).

Why not?

I think my drivers source is not the best place to defining PORT_SI4455,
 but I can't find better place then include/uapi/linux/serial_core.h

Could you please help me where is the correct location for this definition?

I ask as I am trying to figure out why we keep adding these ids, yet no
tool that i know of seems to actually use them.

If you don't have a tool that needs to use a new id, then I would
recommend not adding it, right?

thanks,

greg k-h