From: Faiz Abbas <faiz_abbas@ti.com>
To: Marc Kleine-Budde <mkl@pengutronix.de>,
<linux-kernel@vger.kernel.org>, <devicetree@vger.kernel.org>,
<netdev@vger.kernel.org>, <linux-can@vger.kernel.org>
Cc: <wg@grandegger.com>, <robh+dt@kernel.org>, <mark.rutland@arm.com>,
<kishon@ti.com>
Subject: Re: [PATCH 1/6] phy: Add max_bitrate attribute & phy_get_max_bitrate()
Date: Mon, 5 Nov 2018 11:57:41 +0530 [thread overview]
Message-ID: <d75c9e3c-e12b-e0b8-832c-ad117dcbe990@ti.com> (raw)
In-Reply-To: <5e1a0b67-510a-5512-d477-0b363e4733fe@pengutronix.de>
Hi Marc,
On Saturday 03 November 2018 03:06 PM, Marc Kleine-Budde wrote:
> On 11/02/2018 08:26 PM, Faiz Abbas wrote:
>> In some subsystems (eg. CAN) the physical layer capabilities are
>> the limiting factor in the datarate of the device. Typically, the
>> physical layer transceiver does not provide a way to discover this
>> limitation at runtime. Thus this information needs to be represented as
>> a phy attribute which is read from the device tree.
>>
>> Therefore, add an optional max_bitrate attribute to the generic phy
>> sybsystem. Also add the complementary API which enables the consumer
>> to get max_bitrate.
>>
>> Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
>
> NACK - We already have such a functionality in the CAN subsystem.
> Please have a look at the patches:
>
> e759c626d826 can: m_can: Support higher speed CAN-FD bitrates
> b54f9eea7667 dt-bindings: can: m_can: Document new can transceiver binding
> 2290aefa2e90 can: dev: Add support for limiting configured bitrate
> 54a7fbcc17bc dt-bindings: can: can-transceiver: Document new binding
>
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.
Thanks,
Faiz
next prev parent reply other threads:[~2018-11-05 6:25 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-02 19:26 [PATCH 0/6] Add Support for MCAN transceivers in AM65x-evm Faiz Abbas
2018-11-02 19:26 ` [PATCH 1/6] phy: Add max_bitrate attribute & phy_get_max_bitrate() Faiz Abbas
2018-11-03 9:36 ` Marc Kleine-Budde
2018-11-05 6:27 ` Faiz Abbas [this message]
2018-11-05 9:37 ` Marc Kleine-Budde
2018-11-05 11:14 ` Faiz Abbas
2018-11-05 11:47 ` Marc Kleine-Budde
2018-11-05 13:22 ` Faiz Abbas
2018-11-02 19:26 ` [PATCH 2/6] dt-bindings: phy: phy-of-simple: Document new binding Faiz Abbas
2018-11-06 20:55 ` Rob Herring
2018-11-02 19:26 ` [PATCH 3/6] phy: phy-of-simple: Add support for simple generic phy driver Faiz Abbas
2018-11-03 5:04 ` kbuild test robot
2018-11-02 19:26 ` [PATCH 4/6] dt-bindings: can: m_can: Document transceiver implementation as a phy Faiz Abbas
2018-11-02 19:26 ` [PATCH 5/6] dt-bindings: can: can-transceiver: Remove legacy binding documentation Faiz Abbas
2018-11-03 20:12 ` Sergei Shtylyov
2018-11-02 19:26 ` [PATCH 6/6] can: m_can: Add support for transceiver as phy Faiz Abbas
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