Re: [PATCH 2/3] rtc: imx-sc: Make compatible string more generic

[Trent Piepho <tpiepho@impinj.com>]

On Tue, 2019-06-11 at 17:32 -0300, Fabio Estevam wrote:
> Hi Anson,
> 
> On Tue, Jun 11, 2019 at 3:31 AM <Anson.Huang@nxp.com> wrote:
> > 
> > From: Anson Huang <Anson.Huang@nxp.com>
> > 
> > i.MX system controller RTC driver can support all i.MX SoCs
> > with system controller inside, this patch makes the compatible
> > string more generic to support other i.MX SoCs with system
> > controller inside, such as i.MX8QM etc..
> > 
> > Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
> > ---
> >  drivers/rtc/rtc-imx-sc.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/rtc/rtc-imx-sc.c b/drivers/rtc/rtc-imx-sc.c
> > index c933045..38ef3ca 100644
> > --- a/drivers/rtc/rtc-imx-sc.c
> > +++ b/drivers/rtc/rtc-imx-sc.c
> > @@ -178,7 +178,7 @@ static int imx_sc_rtc_probe(struct
> > platform_device *pdev)
> >  }
> > 
> >  static const struct of_device_id imx_sc_dt_ids[] = {
> > -       { .compatible = "fsl,imx8qxp-sc-rtc", },
> > +       { .compatible = "fsl,imx-sc-rtc", },
> 
> What is wrong with the current compatible string?
> 
> If you want to support i.MX8QM just add in its dtsi:
> 
> compatible = "fsl,imx8qm-sc-rtc", "fsl,imx8qxp-sc-rtc"
> 
> and add a dt-bindings entry for "fsl,imx8qm-sc-rtc"

Yes, I thought this is (was?) the recommended practice for IP blocks in
SoCs that don't have their own version (vs something like a Synopsis
block used many places):

* Use the first SoC to have the block as the base compatible for the
block.
* Always add the current SoC, in additional to the base, in the SoC's
dts's list of compatibles.  Even if unneeded at the present.
* The driver will list the base compatible in the match table, and will
add new ones for specific socs if/when there is a need for it.