[PATCH 2/2] dts: Add u-boot specific 'fsl,mux_mask' property to iomuxc for vf610

[Lukasz Majewski]

Hi Tom,

> On Wed, Jun 25, 2025 at 05:28:56PM +0100, Conor Dooley wrote:
> > On Wed, Jun 25, 2025 at 08:14:24AM -0600, Tom Rini wrote:  
> > > On Wed, Jun 25, 2025 at 08:36:37AM +0200, Lukasz Majewski wrote:  
> > > > Hi Tom,
> > > >   
> > > > > On Tue, Jun 24, 2025 at 10:47:00PM +0200, Lukasz Majewski
> > > > > wrote: 
> > > > > > The commit e8a9521e649f
> > > > > > ("vf500/vf610: synchronise device trees with linux")
> > > > > > has synchronized U-Boot's DTS with v5.19 Linux kernel.
> > > > > > It turned out that in Linux's upstream iomuxc node
> > > > > > description the fsl,mux_mask' was missing, so the U-Boot's
> > > > > > pinctrl driver for NXP's Vybrid SoC was not working
> > > > > > properly.
> > > > > > 
> > > > > > As by default the mux mask was set to 0, the vf610 based
> > > > > > boards (like BK4) were bricked, due to misconfiguration of
> > > > > > gpio at early boot stage.
> > > > > > 
> > > > > > The fix for all vf610 based boards is to introduce
> > > > > > vfxxx-u-boot.dtsi file with 'fsl,mux_mask' property
> > > > > > provided and include it in boards' specific U-Boot
> > > > > > adjustment files (like vf610-bk4r1-u-boot.dtsi).
> > > > > > 
> > > > > > Signed-off-by: Lukasz Majewski <lukma at denx.de>
> > > > > > ---
> > > > > >  arch/arm/dts/vf610-bk4r1-u-boot.dtsi | 2 ++
> > > > > >  arch/arm/dts/vfxxx-u-boot.dtsi       | 9 +++++++++
> > > > > >  2 files changed, 11 insertions(+)
> > > > > >  create mode 100644 arch/arm/dts/vfxxx-u-boot.dtsi    
> > > > > 
> > > > > It looks like this is still missing upstream, so what's the
> > > > > status on that?   
> > > > 
> > > > It looks like in Linux the mux_mask is hardcoded (for Vybrid
> > > > vf610):
> > > > https://elixir.bootlin.com/linux/v6.16-rc3/source/drivers/pinctrl/freescale/pinctrl-vf610.c#L321
> > > > 
> > > > In u-boot other SoCs use it as well, but with different values:
> > > > - arch/arm/dts/imxrt1050.dtsi -> 0x7
> > > > - arch/arm/dts/imx8ulp-evk-u-boot.dtsi -> 0xf00
> > > > 
> > > > In the imx8ulp case above - it is already set in *-u-boot.dtsi
> > > > specific file, so I've followed this approach.  
> > > 
> > > Someone should unify upstream to one approach or another I would
> > > think. Or find a good explanation as to why it's not unified, and
> > > then we should follow.  
> > 
> > If these values are per-SoC, which they appear to be given these
> > look like 3 different devices, I don't see a reason for these to be
> > accepted "upstream".  
> 
> OK, yes. But it should either be "hard code a thing" or "get the
> property" not maybe-one-maybe-the-other? That was what I was trying to
> make as my point.
> 

Agreed.

Then some decision shall be made if:

1. We keep the fsl,mux-mask as *-u-boot.dtsi specific

2. Modify the pinctrl driver for Vybrid
(drivers/pinctrl/nxp/pinctrl-imx-mmio.c) and maybe add mux_mask field
to:
https://source.denx.de/u-boot/u-boot/-/blob/master/drivers/pinctrl/nxp/pinctrl-imx.h?ref_type=heads#L26

3. Try to upstream (to Linux) the property. That would require rewriting
kernel pinctrl driver for vf610 to parse "fsl,mux_mask" property.

As Conor pointed out - the approach from 3. is not feasible.

Then we shall decide if 1. or 2. shall be implemented.

Approach from 1. doesn't require any driver's modification. Approach
from 2. would introduce the extra field and some code modification to:
https://source.denx.de/u-boot/u-boot/-/blob/master/drivers/pinctrl/nxp/pinctrl-imx.c?ref_type=heads
and
https://source.denx.de/u-boot/u-boot/-/blob/master/drivers/pinctrl/nxp/pinctrl-imx-mmio.c?ref_type=heads

I would personally opt for 1.


Best regards,

Lukasz Majewski

--

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