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From: Lucas Stach <l.stach@pengutronix.de>
To: Richard Zhu <hongxing.zhu@nxp.com>,
	andrew.smirnov@gmail.com, shawnguo@kernel.org, kw@linux.com,
	bhelgaas@google.com, stefan@agner.ch, lorenzo.pieralisi@arm.com
Cc: linux-pci@vger.kernel.org, linux-imx@nxp.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, kernel@pengutronix.de
Subject: Re: [PATCH 1/3] dt-bindings: imx6q-pcie: specify the imx8mq pcie phy voltage
Date: Fri, 19 Mar 2021 10:49:29 +0100	[thread overview]
Message-ID: <f501f7da736e6dce90df722033381a0dc0821ad7.camel@pengutronix.de> (raw)
In-Reply-To: <1616142247-13789-1-git-send-email-hongxing.zhu@nxp.com>

Am Freitag, dem 19.03.2021 um 16:24 +0800 schrieb Richard Zhu:
> Both 1.8v and 3.3v power supplies can be feeded to i.MX8MQ PCIe PHY.
> In default, the PCIE_VPH voltage is suggested to be 1.8v refer to data
> sheet. When PCIE_VPH is supplied by 3.3v in the HW schematic design,
> the VREG_BYPASS bits of GPR registers should be cleared from default
> value 1b'1 to 1b'0.
> 
> Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
> ---
>  Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
> index de4b2baf91e8..23efbad9e804 100644
> --- a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
> +++ b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
> @@ -59,6 +59,10 @@ Additional required properties for imx7d-pcie and imx8mq-pcie:
>  Additional required properties for imx8mq-pcie:
>  - clock-names: Must include the following additional entries:
>  	- "pcie_aux"
> +- pcie-vph-3v3: If present then PCIE_VPH is feeded by 3.3v in the HW
> +  schematic design. The PCIE_VPH is suggested to be 1.8v refer to the
> +  data sheet. If the PCIE_VPH is supplied by 3.3V, the VREG_BYPASS
> +  should be cleared to zero accordingly.

Uhm, no. Please don't add boolean DT properties for random parts of the
board design.

If we need to know the voltage of PCIE_VPH, we should really add the
VPH regulator as a supply to the PCIe controller node, then work out
the voltage the usual way by using the Linux regulator API.

Regards,
Lucas


      parent reply	other threads:[~2021-03-19  9:50 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-19  8:24 Richard Zhu
2021-03-19  8:24 ` [PATCH 2/3] arm64: dts: add one property to " Richard Zhu
2021-03-19  8:24 ` [PATCH 3/3] PCI: imx: clear vreg bypass when pcie vph voltage is 3v3 Richard Zhu
2021-03-19  9:49 ` Lucas Stach [this message]

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