Re: [PATCH] clk: iproc: Do not rely on node name for correct PLL setup

[Rafał Miłecki]

On 2022-09-04 17:00, Rafał Miłecki wrote:
> On 2022-08-03 04:58, Florian Fainelli wrote:
> > After commit 31fd9b79dc58 ("ARM: dts: BCM5301X: update CRU block
> > description") a warning from clk-iproc-pll.c was generated due to a
> > duplicate PLL name as well as the console stopped working. Upon closer
> > inspection it became clear that iproc_pll_clk_setup() used the Device
> > Tree node unit name as an unique identifier as well as a parent name 
> > to
> > parent all clocks under the PLL.
> >
> > BCM5301X was the first platform on which that got noticed because of 
> > the
> > DT node unit name renaming but the same assumptions hold true for any
> > user of the iproc_pll_clk_setup() function.
> >
> > The first 'clock-output-names' property is always guaranteed to be
> > unique as well as providing the actual desired PLL clock name, so we
> > utilize that to register the PLL and as a parent name of all children
> > clock.
> >
> > Fixes: 5fe225c105fd ("clk: iproc: add initial common clock support")
> > Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
>
> Acked-by: Rafał Miłecki <rafal@xxxxxxxxxx>
>
>
> Thanks for looking into this!
>
> In the past I debugged this too and even developed a simple fix:
> clk & clock-controller@ DT nodes: __clk_core_init: clk
> clock-controller already initialized
> https://www.spinics.net/lists/linux-clk/msg63855.html
>
> For some reason my old fix didn't work with usbclk clock.

I compared your changes with my old attempt and found the missing bit. I
forgot about updating parent_name.

FWIW something like below would work too.

Thanks again for taking care of this old regression.


diff --git a/drivers/clk/bcm/clk-iproc-pll.c 
b/drivers/clk/bcm/clk-iproc-pll.c
index 33da30f99..af9ca32b8 100644
--- a/drivers/clk/bcm/clk-iproc-pll.c
+++ b/drivers/clk/bcm/clk-iproc-pll.c
@@ -783,7 +783,7 @@ void iproc_pll_clk_setup(struct device_node *node,
 	iclk = &iclk_array[0];
 	iclk->pll = pll;

-	init.name = node->name;
+	init.name = node->full_name;
 	init.ops = &iproc_pll_ops;
 	init.flags = 0;
 	parent_name = of_clk_get_parent_name(node, 0);
@@ -809,7 +809,7 @@ void iproc_pll_clk_setup(struct device_node *node,
 		const char *clk_name;

 		memset(&init, 0, sizeof(init));
-		parent_name = node->name;
+		parent_name = node->full_name;

 		ret = of_property_read_string_index(node, "clock-output-names",
 						    i, &clk_name);