From: Francesco Dolcini <francesco@dolcini.it>
To: Frieder Schrempf <frieder.schrempf@kontron.de>
Cc: Francesco Dolcini <francesco@dolcini.it>,
Wojciech Dubowik <Wojciech.Dubowik@mt.com>,
linux-kernel@vger.kernel.org, Rob Herring <robh@kernel.org>,
Krzysztof Kozlowski <krzk+dt@kernel.org>,
Conor Dooley <conor+dt@kernel.org>,
Shawn Guo <shawnguo@kernel.org>,
Sascha Hauer <s.hauer@pengutronix.de>,
Pengutronix Kernel Team <kernel@pengutronix.de>,
Fabio Estevam <festevam@gmail.com>,
devicetree@vger.kernel.org, imx@lists.linux.dev,
linux-arm-kernel@lists.infradead.org,
Philippe Schenker <philippe.schenker@impulsing.ch>,
stable@vger.kernel.org
Subject: Re: [PATCH v2] arm64: dts: imx8mm-verdin: Link reg_usdhc2_vqmmc to usdhc2
Date: Wed, 23 Apr 2025 12:26:51 +0200 [thread overview]
Message-ID: <20250423102651.GC4811@francesco-nb> (raw)
In-Reply-To: <17ec22a0-b68b-4ac5-b2bc-986837639a37@kontron.de>
On Wed, Apr 23, 2025 at 10:00:22AM +0200, Frieder Schrempf wrote:
> Am 23.04.25 um 09:08 schrieb Francesco Dolcini:
> > On Wed, Apr 23, 2025 at 08:50:54AM +0200, Frieder Schrempf wrote:
> >> Am 22.04.25 um 14:46 schrieb Wojciech Dubowik:
> >>>
> >>> Define vqmmc regulator-gpio for usdhc2 with vin-supply
> >>> coming from LDO5.
> >>>
> >>> Without this definition LDO5 will be powered down, disabling
> >>> SD card after bootup. This has been introduced in commit
> >>> f5aab0438ef1 ("regulator: pca9450: Fix enable register for LDO5").
> >>>
> >>> Fixes: f5aab0438ef1 ("regulator: pca9450: Fix enable register for LDO5")
> >>>
> >>> Cc: stable@vger.kernel.org
> >>> Signed-off-by: Wojciech Dubowik <Wojciech.Dubowik@mt.com>
...
> > With this solution (that I proposed), the sdcard driver just use the
> > GPIO to select the right voltage and that's it, simple, no un-needed i2c
> > communication with the PMIC, and the DT clearly describe the way the HW
> > is designed.
>
> Yes, but your solution relies on the fact that the LDO5 registers
> actually have the correct values for 1v8 and 3v3 setup. The bootloader
> might have changed these values. I would prefer it if we could have a
> solution that puts the LDO5 in a defined state, that is independent from
> any external conditions.
I do not think this is a real concern, the PMIC is programmed during
manufacturing, if the PMIC programming is not correct we have way more
issues ...
Francesco
next prev parent reply other threads:[~2025-04-23 11:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-22 12:46 [PATCH v2] arm64: dts: imx8mm-verdin: Link reg_usdhc2_vqmmc to usdhc2 Wojciech Dubowik
2025-04-22 13:01 ` Francesco Dolcini
2025-04-23 6:50 ` Frieder Schrempf
2025-04-23 7:08 ` Francesco Dolcini
2025-04-23 8:00 ` Frieder Schrempf
2025-04-23 10:26 ` Francesco Dolcini [this message]
2025-04-23 11:22 ` Frieder Schrempf
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