[openwrt/openwrt] ath79: rb912: fix pll init issues

[LEDE Commits]

xback pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/2a000546187122c86143c97337af4d5beacc4908

commit 2a000546187122c86143c97337af4d5beacc4908
Author: Koen Vandeputte <koen.vandeputte at ncentric.com>
AuthorDate: Wed Jan 12 16:11:15 2022 +0100

    ath79: rb912: fix pll init issues
    
    It was reported that some rb912 boards (ar934x) have issues with some ethernet speeds.
    Investigation shows that the board failed to adapt the ethernet pll values as shown here:
    
    [    5.284359] ag71xx 19000000.eth: failed to read pll-handle property
    
    added custom prints in code and triggering a link switch:
    
    [   62.821446] Atheros AG71xx: fast reset
    [   62.826442] Atheros AG71xx: update pll 2
    [   62.830494] Atheros AG71xx: no pll regmap!
    
    Comparison with another very similar board (rb922 - QCA955x) showed a missing
    reference clock frequency in dts, which seems to cause a pll init issue.
    Unfortunately, no errors are printed when this occurs.
    
    Adding the frequency property fixes the pll init as it can be parsed now
    by the ethernet driver.
    
    [   55.861407] Atheros AG71xx: fast reset
    [   55.866403] Atheros AG71xx: update pll 2
    [   55.870462] Atheros AG71xx: ath79_set_pllval: regmap: 0x81548000, pll_reg: 0x2c, pll_val: 0x02000000
    
    Signed-off-by: Sergey Ryazanov <ryazanov.s.a at gmail.com>
    Signed-off-by: Koen Vandeputte <koen.vandeputte at ncentric.com>
---
 target/linux/ath79/dts/ar9342_mikrotik_routerboard-912uag-2hpnd.dts | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/target/linux/ath79/dts/ar9342_mikrotik_routerboard-912uag-2hpnd.dts b/target/linux/ath79/dts/ar9342_mikrotik_routerboard-912uag-2hpnd.dts
index ee2c12b4e0..14286ae8f7 100644
--- a/target/linux/ath79/dts/ar9342_mikrotik_routerboard-912uag-2hpnd.dts
+++ b/target/linux/ath79/dts/ar9342_mikrotik_routerboard-912uag-2hpnd.dts
@@ -127,6 +127,10 @@
 	};
 };
 
+&ref {
+	clock-frequency = <25000000>;
+};
+
 &spi {
 	status = "okay";