[RFC PATCH] arm64: defconfig: Set MFD_TPS6594_I2C as built-in

[Krzysztof Kozlowski]

On 19/08/2024 22:43, Judith Mendez wrote:
> SK-AM62A-LP is a device targeting automotive front-camera applications
> among other use-cases. It utilizes the TPS6593x PMIC (interfaced over I2C)
> to power the SoC and various other peripherals on the board [1].
> 
> MMCSD requires the PMIC to be setup correctly before setting the bus
> pins to 1.8V using the TPS6594 driver interfaced over i2c.
> 
> Currently, the following could be seen when booting the am62ax platform:
> 
> "platform fa00000.mmc: deferred probe pending: platform: supplier regulator-5 not ready"
> "vdd_mmc1: disabling"
> 
> and a failure to boot the SK-AM62A-LP.
> 
> One solution is to use initramfs [2], but using initramfs increases the
> boot time for this automotive solution which requires faster boot time
> parameters.

This is a defconfig, not a distro/product config, so your product
constraints are not really relevant. You are supposed to boot defconfig
with proper initramfs with necessary modules.

I don't get why people mistake defconfig with their product stuff...

> 
> Another solution is to change MFD_TPS6594_I2C to built-in, that way the
> PMIC is setup and the regulators are ready before MMCSD switches to UHS
> mode, this is the preferred solution since it does not increase boot time
> like the initramfs solution does.

Use initramfs. Several devices, e.g. most Android ones, have fixed size
of boot partition, so size of kernel is important.

> 
> [1] https://www.ti.com/lit/zip/sprr459
> [2] https://lore.kernel.org/linux-devicetree/5f03207b-c29b-4d16-92b0-d14eef77bf17@linaro.org/
> Fixes: f9010eb938be ("arm64: defconfig: Enable TPS6593 PMIC for SK-AM62A")

No bug here to be fixed. You miss initramfs.

> 
> Signed-off-by: Judith Mendez <jm at ti.com>


Best regards,
Krzysztof