[OpenWrt-Devel] [PATCH] ramips: Setup missing gpio exports and fine-tune the memory model number.

[John Clark]

 > +            pinctrl-0;
 >> are you sure this bit is correct ?

That is there to override the setting from the parent dtsi file. One 
could argue that the parent dtsi file should not be setting up the 
function of the uart -- this should in fact be done at the dts file 
level.  We can see below in the file for the mt7620a.dtsi that this is 
not set, so there is precedence for taking it out of the dtsi.  I 
hesitated be edit the parent dtsi file as I thought this would pose a 
backward compatibility issue in CC, but perhaps this is the more 
appropriate PR for the main branch.  I am happy to resubmit the PR for 
main to do it like the dtsi for the mt7620a if you like.

https://dev.openwrt.org/browser/trunk/target/linux/ramips/dts/rt5350.dtsi
85                    uart at 500 {
86                            compatible = "ralink,rt5350-uart", 
"ralink,rt2880-uart", "ns16550a";
87                            reg = <0x500 0x100>;
88
89                            resets = <&rstctrl 12>;
90                            reset-names = "uart";
91
92                            interrupt-parent = <&intc>;
93                            interrupts = <5>;
94
95                            reg-shift = <2>;
96
97                            pinctrl-names = "default";
98                            pinctrl-0 = <&uartf_pins>;
99
100                            status = "disabled";
101                    };


https://dev.openwrt.org/browser/trunk/target/linux/ramips/dts/mt7620a.dtsi
85                    uart at 500 {
86                            compatible = "ralink,mt7620a-uart", 
"ralink,rt2880-uart", "ns16550a";
87                            reg = <0x500 0x100>;
88
89                            resets = <&rstctrl 12>;
90                            reset-names = "uart";
91
92                            interrupt-parent = <&intc>;
93                            interrupts = <5>;
94
95                            reg-shift = <2>;
96
97                            status = "disabled";
98                    };


Without clearing the pinctrl-0 in the dts file as I have in my PR, the 
parent dtsi file is asking for the uartf pins to be configured for 
function “uartf” on line 255 of the parent dtsi:

     ralink,function = "uartf";

This dtsi function competes with dts function in the pull request:

     ralink,function = "gpio uartf";

The two conflicting settings will cause a kernel error at boot time.  If 
I take the pinctrl-0; override out, we can see this conflict:

[    0.197413] pinctrl core: add 1 pinctrl maps
[    0.197487] rt2880-pinmux pinctrl: found group selector 2 for uartf
[    0.197526] rt2880-pinmux pinctrl: request pin 7 (io7) for 10000500.uart
[    0.197558] rt2880-pinmux pinctrl: pin io7 already requested by 
pinctrl; cannot claim for 10000500.uart
[    0.197895] rt2880-pinmux pinctrl: pin-7 (10000500.uart) status -22
[    0.198130] rt2880-pinmux pinctrl: could not request pin 7 (io7) from 
group uartf  on device rt2880-pinmux
[    0.198471] of_serial 10000500.uart: Error applying setting, reverse 
things back
[    0.199394] 10000500.uart: ttyS0 at MMIO 0x10000500 (irq = 13, 
base_baud = 2500000) is a Palmchip BK-3103
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