On 7/25/23 13:38, Timur Tabi wrote:

On Mon, Jul 24, 2023 at 1:33 AM Randy Dunlap [off-list ref] wrote:

quoted

Reconcile devices.txt with serial/ucc_uart.c regarding device number
assignments. ucc_uart.c supports 4 ports and uses minor devnums
46-49, so update devices.txt with that info.
Then update ucc_uart.c's reference to the location of the devices.txt
list in the kernel source tree.

Fixes: d7584ed2b994 ("[POWERPC] qe-uart: add support for Freescale QUICCEngine UART")
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Randy Dunlap <redacted>
Cc: Timur Tabi <timur@kernel.org>
Cc: Kumar Gala <redacted>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: linux-serial@vger.kernel.org
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org

Acked-by: Timur Tabi <timur@kernel.org>

One thing does concern me.  The UCC UART driver piggy-backs on the CPM
driver's layout (see cpm_uart.h), but apparently CPM UART supports 6
devices, not four:

#define UART_NR        fs_uart_nr

where fs_uart_nr is defined in enum fs_uart_id.

Unfortunately, it's been so long since I've touched this code, I'm not
sure whether this means anything.

If CPM UART code ever worked with > 4 ports, it probably just used minor devnums
that were not allocated to it.

Also, it looks like the CPU UART part of Documentation/admin-guide/devices.txt
needs to be updated:

		 46 = /dev/cucpm0		Callout device for ttyCPM0
		    ...
		 49 = /dev/cucpm5		Callout device for ttyCPM5

The driver must use some tricks to get 6 ports into 4 devnums. :)


-- 
~Randy