Re: [PATCH 2/2] pinctrl: spacemit: add clock support for K1 SoC

[Yixun Lan]

Hi Rob,

On 14:38 Tue 15 Apr     , Rob Herring wrote:
> On Sat, Apr 12, 2025 at 10:34:31PM +0000, Yixun Lan wrote:
> > Hi Rob,
> > 
> > On 13:27 Sat 12 Apr     , Rob Herring wrote:
> > > On Sat, Apr 12, 2025 at 02:58:11PM +0800, Yixun Lan wrote:
> > > > For SpacemiT K1 SoC's pinctrl, explicitly acquiring clocks in
> > > > the driver instead of relying on bootloader or default hardware
> > > > settings to enable it.
> > > > 
> > > > Signed-off-by: Yixun Lan <dlan@xxxxxxxxxx>
> > > > ---
> > > >  drivers/pinctrl/spacemit/pinctrl-k1.c | 10 ++++++++++
> > > >  1 file changed, 10 insertions(+)
> > > > 
> > > > diff --git a/drivers/pinctrl/spacemit/pinctrl-k1.c b/drivers/pinctrl/spacemit/pinctrl-k1.c
> > > > index 67e867b04a02ea1887d93aedfdea5bda037f88b1..3805fb09c1bc3b8cf2ccfc22dd25367292b397b9 100644
> > > > --- a/drivers/pinctrl/spacemit/pinctrl-k1.c
> > > > +++ b/drivers/pinctrl/spacemit/pinctrl-k1.c
> > > > @@ -2,6 +2,7 @@
> > > >  /* Copyright (c) 2024 Yixun Lan <dlan@xxxxxxxxxx> */
> > > >  
> > > >  #include <linux/bits.h>
> > > > +#include <linux/clk.h>
> > > >  #include <linux/cleanup.h>
> > > >  #include <linux/io.h>
> > > >  #include <linux/of.h>
> > > > @@ -721,6 +722,7 @@ static int spacemit_pinctrl_probe(struct platform_device *pdev)
> > > >  {
> > > >  	struct device *dev = &pdev->dev;
> > > >  	struct spacemit_pinctrl *pctrl;
> > > > +	struct clk *func_clk, *bus_clk;
> > > >  	const struct spacemit_pinctrl_data *pctrl_data;
> > > >  	int ret;
> > > >  
> > > > @@ -739,6 +741,14 @@ static int spacemit_pinctrl_probe(struct platform_device *pdev)
> > > >  	if (IS_ERR(pctrl->regs))
> > > >  		return PTR_ERR(pctrl->regs);
> > > >  
> > > > +	func_clk = devm_clk_get_optional_enabled(dev, "func");
> > > > +	if (IS_ERR(func_clk))
> > > > +		return dev_err_probe(dev, PTR_ERR(func_clk), "failed to get func clock\n");
> > > > +
> > > > +	bus_clk = devm_clk_get_optional_enabled(dev, "bus");
> > > > +	if (IS_ERR(bus_clk))
> > > > +		return dev_err_probe(dev, PTR_ERR(bus_clk), "failed to get bus clock\n");
> > > 
> > > Do you really need these to be optional? Yes, it maintains 
> > >
> > Yes, the motivation here to make it optional is maintaining the 
> > compatibility, to not break the case of using old dtb with new kernel,
> > since the serial console device (uart0) is activated now [1]
> > 
> > IIUC, from the DT perspective, it's mandatory to keep this compatibility?
> 
> It's up to the platform. It's only mandatory to understand you are 
> breaking compatibility when you do.
> 
> > 
> > In dt-binding of patch [1/2], the clocks/clock-names has been described as 
> > required property, so it's sort of mandatory from DT's view.
> > 
> > One lesson I learned is that the pinctrl dt node shouldn't be activated
> > untill all prerequisite dependencies meet.. it's ok to push the driver,
> > but should postpone the DT part..
> > 
> > > compatibility, but if this platform isn't stable, then do you really 
> > > need that?
> > > 
> > I don't get what's your meaning of "isn't stable" here, the fact won't
> > change for K1 SoC: the pinctrl controller requires two clocks
> 
> You required 1 clock and now you require 2. That's not stable. 
previously pinctrl requires no clock (no clock property populated)

> Generally, early on with platforms, their DT is not complete enough to 
> maintain compatibility. There's also likely not many users or h/w 
> availability for compatibility to be an issue. So requiring the DT to be 
> in-sync with the kernel is not a problem.
> 
Ok, then in this case, I will simply drop this _optional_ API

thanks

-- 
Yixun Lan (dlan)
Gentoo Linux Developer
GPG Key ID AABEFD55