linux-kernel - Re: [PATCH 1/6] phy: Add max_bitrate attribute & phy_get_max

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Date:   Mon, 5 Nov 2018 16:44:12 +0530
From:   Faiz Abbas <faiz_abbas@...com>
To:     Marc Kleine-Budde <mkl@...gutronix.de>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <netdev@...r.kernel.org>, <linux-can@...r.kernel.org>
CC:     <wg@...ndegger.com>, <robh+dt@...nel.org>, <mark.rutland@....com>,
        <kishon@...com>
Subject: Re: [PATCH 1/6] phy: Add max_bitrate attribute &
 phy_get_max_bitrate()

Hi,

On Monday 05 November 2018 03:07 PM, Marc Kleine-Budde wrote:
> On 11/05/2018 07:27 AM, Faiz Abbas wrote:
>> I remove the transceiver child node binding documentation in patch 5/6.
>>
>> The existing implementation is pretty limiting as it just has a child
>> node with no associated device. What if a transceiver requires its own
>> configurations before it can start sending/receiving messages (for
>> example, my usecase requires it to pull the standby line low)?
>>
>> I think that can be solved by implementing the transceiver as a phy and
>> exposing a generic get_max_bitrate API. That way, the transceiver device
>> can do all its startup configuration in the phy probe function.
>>
>> In any case, do suggest if you have a better idea on how to implement
>> pull gpio low requirement.
> 
> As long as we don't have any proper transceiver/phy driver, that does
> more than swtich on/off a GPIO, please add a "xceiver" regulator to your
> driver. Look for:
> 
>> devm_regulator_get(&pdev->dev, "xceiver");
> 

The transceiver is not specific to m_can. The pull down would be
required even if it were connected to some other controller.

Thanks,
Faiz