Re: [PATCH v8 8/9] riscv: dts: spacemit: k1-bananapi-f3: add SD card support with UHS modes

From: "Troy Mitchell" <troy.mitchell@linux.dev>
To: "Iker Pedrosa" <ikerpedrosam@gmail.com>,
	"Margherita Milani" <margherita.milani@amarulasolutions.com>
Cc: Rob Herring <robh@kernel.org>, Conor Dooley <conor+dt@kernel.org>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Michael Opdenacker <michael.opdenacker@rootcommit.com>,
	Alexandre Ghiti <alex@ghiti.fr>,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	Troy Mitchell <troy.mitchell@linux.dev>,
	linux-mmc@vger.kernel.org, Ulf Hansson <ulf.hansson@linaro.org>,
	linux-riscv@lists.infradead.org,
	Adrian Hunter <adrian.hunter@intel.com>,
	Palmer Dabbelt <palmer@dabbelt.com>, Yixun Lan <dlan@kernel.org>,
	Javier Martinez Canillas <javierm@redhat.com>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	spacemit@lists.linux.dev, Paul Walmsley <pjw@kernel.org>
Subject: Re: [PATCH v8 8/9] riscv: dts: spacemit: k1-bananapi-f3: add SD card support with UHS modes
Date: Thu, 07 May 2026 18:45:07 +0800	[thread overview]
Message-ID: <DICDTHYTPDSP.210EBVHTQ6966@linux.dev> (raw)
In-Reply-To: <CABdCQ=OsPva9=YPdBd=3HW1OO7=_zJtpXjvaiA0WLEDT5Scs_Q@mail.gmail.com>

On Thu May 7, 2026 at 5:53 PM CST, Iker Pedrosa wrote:
> Hi,
>
> El jue, 7 may 2026 a las 10:20, Margherita Milani
> (<margherita.milani@amarulasolutions.com>) escribió:
>>
>> Good morning Iker,
>>
>> > Add complete SD card controller support with UHS high-speed modes.
>> >
>> > - Enable sdhci0 controller with 4-bit bus width
>> > - Configure card detect GPIO with inversion
>> > - Connect vmmc-supply to buck4 for 3.3V card power
>> > - Connect vqmmc-supply to aldo1 for 1.8V/3.3V I/O switching
>> > - Add dual pinctrl states for voltage-dependent pin configuration
>> > - Support UHS-I SDR25, SDR50, and SDR104 modes
>>
>>
>> Tested-by: Margherita Milani <margherita.milani@amarulasolutions.com>
>>
>> However I noticed it only works when CONFIG_I2C_K1 is enabled.
>> Michael Opdenacker told me it's necessary to enable the regulators
>> used by the mmc controller.
>> Should we add the dependency between CONFIG_MMC_SDHCI_OF_K1 and
>> CONFIG_I2C_K1? (Unless some boards don't have these dependency?)
>> Thank you for your patchset which was really nice!
>
> Thank you for catching this! You're absolutely right about the dependency.
>
> From what I can see, all current SpacemiT K1 boards follow this design
> pattern where the SD card power is provided by an I2C-controlled PMIC.
> However, before adding a hard dependency, I'd like to get input from
> the community, does anyone know of K1-based boards that provide SD
> card power through fixed regulators or other means that don't require
> I2C?
if K1 needs to switch between standard and high-speed (UHS) modes,
I believe the I2C-controlled PMIC is mandatory to handle the voltage
switching (typically 3.3V to 1.8V).

I don't think any board would want to be stuck in standard mode permanently.
If high-speed mode is an option, why not use it? I think adding this
dependency is a good idea, but keep in mind it also needs to depend on P1.

                            - Troy

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