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SubjectRe: [PATCH] mmc: meson: initial ocr available by default value
Date

On Mon 13 Dec 2021 at 19:50, "rong.chen@amlogic.com" <rong.chen@amlogic.com> wrote:

> Hello,
> If 3.3V always-on power source for vmmc is supplied by hardware boards fixed, don't need regulator in software, so .dts unnecessary the link between regulator
> and MMC controller vmmc/vqmmc.

Controllable or not, your vmmc/vqmmc regulators should be described in
DT.

There are several examples of this in arch/arm64/boot/dts/amlogic/*.dts


>
> ------------------------------------------------------------------------------------------------------------------------------------------------------
> rong.chen@amlogic.com
>
>
> From: Martin Blumenstingl
> Date: 2021-12-13 16:00
> To: Rong Chen
> CC: Ulf Hansson; Neil Armstrong; Kevin Hilman; Jerome Brunet; --to=1131046452; 45581586; linux-mmc; linux-arm-kernel; linux-amlogic; linux-kernel
> Subject: Re: [PATCH] mmc: meson: initial ocr available by default value
> [ EXTERNAL EMAIL ]
>
> Hello,
>
> On Mon, Dec 13, 2021 at 8:03 AM Rong Chen <rong.chen@amlogic.com> wrote:
> >
> > The patch will add a value of ocr supported by the controller,
> > to specify some of voltage values are supported.
> Can you please share some details on this topic?
>
> We already have many boards upstreamed which work fine without
> manually setting ocr_avail in the driver.
> In general there's two types of boards:
> 1) boards where the regulator can switch between different voltages.
> One example is the Odroid-C2, see meson-gxbb-odroidc2.dts [0]
> Here we specify:
> vmmc-supply = <&tflash_vdd>;
> vqmmc-supply = <&tf_io>;
> &tflash_vdd is either turned off or at 3.3V when turned on.
> &tf_io can be either turned off, 1.8V or 3.3V.
>
> 2) boards where the voltages are fixed.
> One example is Radxa Zero, see meson-g12a-radxa-zero.dts [1]
> For the SD card the board uses:
> vmmc-supply = <&vddao_3v3>;
> vqmmc-supply = <&vddao_3v3>;
> (meaning fixed 3.3V always-on power source for both VMMC and VQMMC)
> and for eMMC the board uses:
> vmmc-supply = <&vcc_3v3>;
> vqmmc-supply = <&vcc_1v8>;
> (meaning: 3.3V always-on power source for vmmc and 1.8V always-on
> power source for VQMMC)
>
> With the information from the regulators the MMC core will
> automatically detect ocr_avail in Linux.
> Or in other words: your .dts may be missing the link between regulator
> and MMC controller vmmc/vqmmc.
> Can you please double-check this?
>
>
> Best regards,
> Martin
>
>
> [0]
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts?id=2585cf9dfaaddf00b069673f27bb3f8530e2039c#n354
>
> [1]
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/amlogic/meson-g12a-radxa-zero.dts?id=2585cf9dfaaddf00b069673f27bb3f8530e2039c#n333

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