On Fri, 21 Jul 2023 13:24:19 -0600
Rob Herring [off-list ref] wrote:

On Fri, Jul 21, 2023 at 10:19 AM Hugo Villeneuve [off-list ref] wrote:

quoted

From: Hugo Villeneuve <hvilleneuve@dimonoff.com>

Commit 679875d1d880 ("sc16is7xx: Separate GPIOs from modem control lines")
and commit 21144bab4f11 ("sc16is7xx: Handle modem status lines")
changed the function of the GPIOs pins to act as modem control
lines without any possibility of selecting GPIO function.

Requiring a new DT property is not fixing a kernel regression. You
should be returning the kernel to original behavior and then have a
new DT property for new behavior.

Hi Rob,
please read the entire patch history starting from V1
 and you will understand why this course of action was
 not selected.

 

quoted

As a consequence, applications that depends on GPIO lines configured
by default as GPIO pins no longer work as expected.

Also, the change to select modem control lines function was done only
for channel A of dual UART variants (752/762). This was not documented
in the log message.

Allow to specify GPIO or modem control line function in the device
tree, and for each of the ports (A or B).

Do so by using the new device-tree property named
"modem-control-line-ports" (property added in separate patch).

That's not the name in the patch.

We added a "nxp," prefix at some point.

Do you want me to send a V9 only with this change?

Hugo.

quoted

When registering GPIO chip controller, mask-out GPIO pins declared as
modem control lines according to this new "modem-control-line-ports"
DT property.

Boards that need to have GPIOS configured as modem control lines
should add that property to their device tree. Here is a list of
boards using the sc16is7xx driver in their device tree and that may
need to be modified:
    arm64/boot/dts/freescale/fsl-ls1012a-frdm.dts
    mips/boot/dts/ingenic/cu1830-neo.dts
    mips/boot/dts/ingenic/cu1000-neo.dts

Then again, if no one cares about those boards needing a change then
it can be okay.


Rob

-- 
Hugo Villeneuve [off-list ref]