Re: [PATCH v4 1/2] mtd: rawnand: meson: discard the common MMC sub clock framework

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hello,

liang.yang@amlogic.com wrote on Mon, 18 Apr 2022 11:40:10 +0800:

> Hi Miquel,
> 
> i have some confusion when i prepare the patches. for DT compatibility, it falls back to the old DT when failed to get resource by the new DT, but there is some points:
> a. old DT depends on MMC sub clock driver, but it never be merged, so it can't work.

I don't get what you mean here, sorry. I believe there is a new way to
describe this clock but grabbing the one from the MMC still works, does
not it?

> b. if it falls back to the old DT, beside the regmap lookup below, it seems that we have to preserve the code of the old clock setting in nfc_clk_init().

Yes, probably.

> do we still need to avoid break DT compatibility?

We should try our best to avoid breaking the DT, yes.

> 
> Thanks.
> 
> On 2022/4/11 10:40, Liang Yang wrote:
> >>>       nfc->dev = dev;
> >>> -    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >>> -    nfc->reg_base = devm_ioremap_resource(dev, res);
> >>> +    nfc->reg_base = devm_platform_ioremap_resource_byname(pdev, "nfc");  
> >>
> >> This change seems unrelated.  
> > 
> > To be consistent with the following > devm_platform_ioremap_resource_byname(pdev, "emmc"). do you mean that we > don't need it?>  
> >>>       if (IS_ERR(nfc->reg_base))
> >>>           return PTR_ERR(nfc->reg_base);
> >>> -    nfc->reg_clk =
> >>> -        syscon_regmap_lookup_by_phandle(dev->of_node,
> >>> -                        "amlogic,mmc-syscon");
> >>> -    if (IS_ERR(nfc->reg_clk)) {
> >>> -        dev_err(dev, "Failed to lookup clock base\n");
> >>> -        return PTR_ERR(nfc->reg_clk);
> >>> -    }
> >>> +    nfc->sd_emmc_clock = devm_platform_ioremap_resource_byname(pdev, >>> "emmc");
> >>> +    if (IS_ERR(nfc->sd_emmc_clock))
> >>> +        return PTR_ERR(nfc->sd_emmc_clock);  
> >>
> >> While I agree this is much better than the previous solution, we cannot
> >> break DT compatibility, so you need to try getting the emmc clock, but
> >> if it fails you should fallback to the regmap lookup.  
> > 
> > ok, i will fix it next version. thanks.
> >   
> >>  
> >>>       irq = platform_get_irq(pdev, 0);  


Thanks,
Miquèl