linux-kernel - Re: [PATCH 4/4] can: m_can_platform: Add support for transceiver as phy

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Message-ID: <9509372e-60f1-85cf-cc22-f7c1e66ae738@pengutronix.de>
Date:   Mon, 12 Apr 2021 12:22:26 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Aswath Govindraju <a-govindraju@...com>
Cc:     Vignesh Raghavendra <vigneshr@...com>,
        Kishon Vijay Abraham I <kishon@...com>,
        Lokesh Vutla <lokeshvutla@...com>,
        Grygorii Strashko <grygorii.strashko@...com>,
        Faiz Abbas <faiz_abbas@...com>,
        Chandrasekar Ramakrishnan <rcsekar@...sung.com>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Vinod Koul <vkoul@...nel.org>,
        Sriram Dash <sriram.dash@...sung.com>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-phy@...ts.infradead.org
Subject: Re: [PATCH 4/4] can: m_can_platform: Add support for transceiver as
 phy

On 4/9/21 3:40 PM, Aswath Govindraju wrote:
> From: Faiz Abbas <faiz_abbas@...com>
> 
> Add support for implementing transceiver node as phy. The max_bitrate is
> obtained by getting a phy attribute.
> 
> Signed-off-by: Faiz Abbas <faiz_abbas@...com>
> Signed-off-by: Aswath Govindraju <a-govindraju@...com>
> ---
>  drivers/net/can/m_can/m_can_platform.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/net/can/m_can/m_can_platform.c b/drivers/net/can/m_can/m_can_platform.c
> index 599de0e08cd7..4a762b5a21d8 100644
> --- a/drivers/net/can/m_can/m_can_platform.c
> +++ b/drivers/net/can/m_can/m_can_platform.c
> @@ -6,6 +6,7 @@
>  // Copyright (C) 2018-19 Texas Instruments Incorporated - http://www.ti.com/
>  
>  #include <linux/platform_device.h>
> +#include <linux/phy/phy.h>
>  
>  #include "m_can.h"
>  
> @@ -67,7 +68,9 @@ static int m_can_plat_probe(struct platform_device *pdev)
>  	struct resource *res;
>  	void __iomem *addr;
>  	void __iomem *mram_addr;
> +	struct phy *transceiver;
>  	int irq, ret = 0;
> +	u32 bitrate_max;
>  
>  	mcan_class = m_can_class_allocate_dev(&pdev->dev,
>  					      sizeof(struct m_can_plat_priv));
> @@ -101,6 +104,28 @@ static int m_can_plat_probe(struct platform_device *pdev)
>  		goto probe_fail;
>  	}
>  
> +	transceiver = devm_phy_optional_get(&pdev->dev, "can_transceiver");
> +	if (IS_ERR(transceiver)) {
> +		ret = PTR_ERR(transceiver);
> +		dev_err(&pdev->dev, "error while getting phy, err=%d\n", ret);
> +		return ret;
> +	}
> +
> +	if (!transceiver) {
> +		dev_warn(&pdev->dev, "No transceiver phy found\n");

I think that's a bit to loud.

> +	} else {
> +		ret = phy_power_on(transceiver);

Please move the phy power on/off to the ndo_open and ndo_stop callbacks. There's
no need to power the transceivers if the CAN interface is down.

> +		if (ret) {
> +			dev_err(&pdev->dev, "error powering on phy, err=%d\n", ret);
> +			return ret;
> +		}
> +		/* converting from Mbps to bps */
> +		bitrate_max = (transceiver->attrs.max_link_rate) * 1000000;
> +		if (!bitrate_max)
> +			dev_warn(&pdev->dev, "Invalid value for transceiver max bitrate. Ignoring bitrate limit\n");

Please move this check to the generic transcevier code.

> +		priv->cdev.can.bitrate_max = bitrate_max;
> +	}
> +
>  	priv->base = addr;
>  	priv->mram_base = mram_addr;
>  
> 

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
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