Re: [PATCH v3 3/3] net: cdc_ncm: Add ACPI MAC address pass through functionality

[Greg KH <greg@kroah.com>]

On Thu, Sep 05, 2019 at 08:51:15PM -0500, Charles Hyde wrote:
> This change adds support to cdc_ncm for ACPI MAC address pass through
> functionality that also exists in the Realtek r8152 driver.  This is in
> support of Dell's Universal Dock D6000, to give it the same feature
> capability as is currently available in Windows and advertized on Dell's
> product web site.
> 
> Today's v3 patch series includes a function named get_ethernet_addr()
> which replaces two instances where the same code snippet was located in
> teh previous patch series.  I also created a post reset function to set
> the MAC address, if there exists an ACPI MAC address pass through (MAPT)
> method.  Oliver Neukum had requested a post reset function for this
> purpose.
> 
> Signed-off-by: Charles Hyde <charles.hyde@dellteam.com>
> Cc: Mario Limonciello <mario.limonciello@dell.com>
> Cc: chip.programmer@gmail.com
> Cc: Oliver Neukum <oliver@neukum.org>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Len Brown <lenb@kernel.org>
> Cc: linux-usb@vger.kernel.org
> Cc: linux-acpi@vger.kernel.org
> ---
>  drivers/net/usb/cdc_ncm.c | 74 +++++++++++++++++++++++++++++++++------
>  1 file changed, 64 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
> index 85093579612f..e0152d44f5af 100644
> --- a/drivers/net/usb/cdc_ncm.c
> +++ b/drivers/net/usb/cdc_ncm.c
> @@ -52,6 +52,7 @@
>  #include <linux/usb/usbnet.h>
>  #include <linux/usb/cdc.h>
>  #include <linux/usb/cdc_ncm.h>
> +#include <acpi/acpi_mac_passthru.h>
>  
>  #if IS_ENABLED(CONFIG_USB_NET_CDC_MBIM)
>  static bool prefer_mbim = true;
> @@ -833,6 +834,45 @@ static const struct net_device_ops cdc_ncm_netdev_ops = {
>  	.ndo_validate_addr   = eth_validate_addr,
>  };
>  
> +static int get_ethernet_addr(struct usb_interface *intf)
> +{
> +	struct sockaddr sa;
> +	struct usbnet *dev = usb_get_intfdata(intf);
> +	struct cdc_ncm_ctx *ctx;
> +	int ret = 0;
> +
> +	if (!dev)
> +		return 0;
> +
> +	ctx = (struct cdc_ncm_ctx *)dev->data[0];
> +	if (!ctx->ether_desc)
> +		return 0;
> +
> +	ret = cdc_ncm_get_ethernet_address(dev, ctx);
> +	if (ret) {
> +		dev_dbg(&intf->dev, "failed to get mac address\n");
> +		return ret;
> +	}
> +
> +	/* Check for a Dell Universal Dock D6000 before checking if ACPI
> +	 * supports MAC address pass through.
> +	 */
> +	if (strstr(dev->udev->product, "D6000")) {

As other people have pointed out, that's funny.

No, this is explicitly what the USB vendor/product ids are for, don't
try to make up something that will be guaranteed to not work
correctly...

> +		sa.sa_family = dev->net->type;
> +		if (get_acpi_mac_passthru(sa.sa_data)) {
> +			if (!memcmp(dev->net->dev_addr, sa.sa_data,
> +				    ETH_ALEN)) {
> +				if (!cdc_ncm_set_ethernet_address(dev, &sa))
> +					memcpy(dev->net->dev_addr, sa.sa_data,
> +					       ETH_ALEN);
> +			}
> +		}
> +	}
> +	dev_info(&intf->dev, "MAC-Address: %pM\n", dev->net->dev_addr);

If a driver is working properly, it should not spit out any kernel log
messages.  Make this dev_dbg() if you need it for your own debugging
logic.

thanks,

greg k-h