Re: [PATCH] sh: sh7785lcr: register the PCA9564 as I2C bus 0

[John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>]

On Sat, 2026-10-03 at 11:07 +0200, John Paul Adrian Glaubitz wrote:
> On Sat, 2026-10-03 at 10:28 +0200, Karl Mehltretter wrote:
> > The R2025S/D board information is registered on I2C bus 0. Commit
> > 44454baa7ca7 ("i2c: Dynamically assign adapter id if it wasn't explictly
> > specified") changed the PCA9564 platform driver to pass negative platform
> > device IDs to the I2C core. The SH7785LCR device uses ID -1, so the core
> > assigns it a dynamic bus number. Reserving bus 0 for the board information
> > makes i2c-1 the first dynamic bus, and the RTC is never instantiated.
> > 
> > Set the platform device ID to 0 so the adapter is registered as i2c-0 and
> > the RTC board information matches it.
> > 
> > Fixes: 44454baa7ca7 ("i2c: Dynamically assign adapter id if it wasn't explictly specified")
> > Assisted-by: LLM
> > Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
> > ---
> > 
> > Tested with 29-bit and 32-bit kernels on a custom QEMU model of the
> > SH7785LCR. Both registered the controller as i2c-0 and the R2025S/D as
> > rtc0.
> > Testing on real hardware is welcome.
> > 
> >  arch/sh/boards/board-sh7785lcr.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/arch/sh/boards/board-sh7785lcr.c b/arch/sh/boards/board-sh7785lcr.c
> > index 25c4968f0d8b..b93423df582f 100644
> > --- a/arch/sh/boards/board-sh7785lcr.c
> > +++ b/arch/sh/boards/board-sh7785lcr.c
> > @@ -256,7 +256,7 @@ static struct i2c_pca9564_pf_platform_data i2c_platform_data = {
> >  
> >  static struct platform_device i2c_device = {
> >  	.name		= "i2c-pca-platform",
> > -	.id		= -1,
> > +	.id		= 0,
> >  	.dev		= {
> >  		.platform_data	= &i2c_platform_data,
> >  	},
> 
> Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>

I have to admit though I don't fully understand the description of this
patch. Either I don't have enough coffee or it's not precise enough.

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer
`. `'   Physicist
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913