Re: Re: [PATCH 1/3] mmc:sunxi-mmc:add support on discrete device power supply

["michael@allwinnertech.com" <michael@allwinnertech.com>]

> From: Ulf Hansson
> Date: 2021-12-29 00:49
> To: Michael Wu
> CC: mripard; wens; samuel; andre.przywara; jernej.skrabec; linux-mmc; linux-arm-kernel; linux-sunxi; linux-kernel
> Subject: Re: [PATCH 1/3] mmc:sunxi-mmc:add support on discrete device power supply
> On Wed, 22 Dec 2021 at 04:07, Michael Wu <michael@allwinnertech.com> wrote:
> >
> > Because some platform has no regulator, only use discrete devices
> > to supply power,For this situation, to use sd/mmc card, we add ocr manually
> >
> > Signed-off-by: Michael Wu <michael@allwinnertech.com>
> > ---
> >  drivers/mmc/host/sunxi-mmc.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c
> > index 2702736a1c57..afeefead6501 100644
> > --- a/drivers/mmc/host/sunxi-mmc.c
> > +++ b/drivers/mmc/host/sunxi-mmc.c
> > @@ -1300,6 +1300,14 @@ static int sunxi_mmc_resource_request(struct sunxi_mmc_host *host,
> >         if (ret)
> >                 return ret;
> >
> > +       /**
> > +        * Some platforms has no regulator. Discrete devices are used instead.
> > +        * To support sd/mmc card, we need to add ocr manually.
> > +        */
> > +       if (!host->mmc->ocr_avail)
> > +               host->mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;
> > +
> 
> Rather than doing this, I suggest you hook up a fixed vmmc regulator in the DTS.
> 
> Nevertheless, it seems reasonable to check that the ocr_avail gets set
> up correctly. And if it doesn't, perhaps we should print a warning and
> return an error code.
> 
> > +
> >         host->reg_base = devm_platform_ioremap_resource(pdev, 0);
> >         if (IS_ERR(host->reg_base))
> >                 return PTR_ERR(host->reg_base);
> 
> Kind regards
> Uffe

Dear Uffe,
Thanks for your suggestion. It is a better solution.
I've modified my patch. Please check if it's reasonable. If it is, I'll re-sumbit it later.

---
Subject: [PATCH v2] mmc: sunxi-mmc: check ocr_avail on resource request

Some platforms have no regulator, discrete power devices are used instead.
However, sunxi_mmc_probe does not catch this exception when regulator is
absent in DTS. This leads to sd or eMMC init failure.
To solve this, a fixed vmmc regulator must be hooked up in DTS, like this:
reg_dummy_vmmc: dummy_vmmc {
	compatible = "regulator-fixed";
	regulator-name = "dummy-vmmc";
	regulator-min-microvolt = <500000>;
	regulator-max-microvolt = <3500000>;
};
mmc0:mmc@4020000 {
	compatible = "allwinner,sun50i-a100-emmc";
	device_type = "mmc0";
	vmmc-supply = <&reg_dummy_vmmc>;
}
In this patch, we print an error message and abort the probe process if
the regulator is not specified in DTS.

Signed-off-by: Michael Wu <michael@allwinnertech.com>
---

diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c
index 2702736..0da74bd 100644
--- a/drivers/mmc/host/sunxi-mmc.c
+++ b/drivers/mmc/host/sunxi-mmc.c
@@ -1300,6 +1300,11 @@
 	if (ret)
 		return ret;
 
+	if (!host->mmc->ocr_avail) {
+		dev_err(&pdev->dev, "Could not get mmc regulator\n");
+		return -EINVAL;
+	}
+
 	host->reg_base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(host->reg_base))
 		return PTR_ERR(host->reg_base);

Best Regards,
Michael Wu
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