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From: Andrew Lunn <andrew@lunn.ch>
To: Stefan Wahren <stefan.wahren@i2se.com>
Cc: "David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Michael Heimpold <michael.heimpold@in-tech.com>,
	jimmy.shen@vertexcom.com, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
Subject: Re: [PATCH RFC 3/3] net: vertexcom: Add MSE102x SPI support
Date: Thu, 16 Sep 2021 14:35:41 +0200	[thread overview]
Message-ID: <YUM6HfDYX0Twe67+@lunn.ch> (raw)
In-Reply-To: <bfbbf816-f467-7e2e-12ca-fb2172ce93f9@i2se.com>

> >> +	netif_carrier_off(mse->ndev);
> >> +	ndev->if_port = IF_PORT_10BASET;
> > That is not correct. Maybe you should add a IF_PORT_HOMEPLUG ?


> There is already a driver (qca_spi, qcauart) for a similiar Homeplug
> device (QCA7000), which also uses IF_PORT_10BASET. Should i change this
> too or leave it because of resulting changes to userspace?

Technically, it would be an ABI change. But ifmap seems pretty loosely
defined. See man 7 netdevice:

       SIOCGIFMAP, SIOCSIFMAP
              Get or set the interface's hardware parameters using ifr_map.
	      Setting the parameters is a privileged operation.

                  struct ifmap {
                      unsigned long   mem_start;
                      unsigned long   mem_end;
                      unsigned short  base_addr;
                      unsigned char   irq;
                      unsigned char   dma;
                      unsigned char   port;
                  };

              The interpretation of the ifmap structure depends on the device driver
	      and the architecture.

The if_port value ends up in port. And i've no idea where it is
actually available in user space. iproute2 does not use it, nor
ethtool. So, i would say, submit a separate patch for the other
drivers, and we will see if anybody notices.

> >> +static const struct of_device_id mse102x_match_table[] = {
> >> +	{ .compatible = "vertexcom,mse1021" },
> >> +	{ .compatible = "vertexcom,mse1022" },
> > Is there an ID register you can read to determine what device you
> > actually have? If so, i suggest you verify the correct compatible is
> > used.
> 
> AFAIK the device doesn't have any kind of ID register.

Then i would suggest changing the compatible to "vertexcom,mse102x".

If you cannot verify it, and it makes no actual difference, then 50%
of the boards will use the wrong one. Which means you can then later
not actually make use of it to enable features specific to a
compatible string.

	   Andrew

  reply	other threads:[~2021-09-16 12:35 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-14 15:17 [PATCH RFC 0/3] add Vertexcom MSE102x support Stefan Wahren
2021-09-14 15:17 ` [PATCH RFC 1/3] dt-bindings: add vendor Vertexcom Stefan Wahren
2021-09-21 20:55   ` Rob Herring
2021-09-14 15:17 ` [PATCH RFC 2/3] dt-bindings: net: add Vertexcom MSE102x support Stefan Wahren
2021-09-21 21:09   ` Rob Herring
2021-09-14 15:17 ` [PATCH RFC 3/3] net: vertexcom: Add MSE102x SPI support Stefan Wahren
2021-09-15  2:55   ` Jakub Kicinski
2021-09-15 21:17   ` Andrew Lunn
2021-09-16 11:12     ` Stefan Wahren
2021-09-16 12:35       ` Andrew Lunn [this message]
2021-09-21 21:07         ` Rob Herring
2021-09-16 11:26     ` Michael Heimpold
2021-09-16 12:46       ` Andrew Lunn

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