Subject: Re: [PATCH] r8169: Load MAC address from device tree if present

From: Thierry Reding <[email-masked]>
Date: Fri, 25 Jan 2019 16:33:10 +0100

On Fri, Jan 25, 2019 at 03:57:11PM +0100, Andrew Lunn wrote:
> On Fri, Jan 25, 2019 at 11:18:14AM +0100, Thierry Reding wrote:
> > From: Thierry Reding <[email-masked]>
> > 
> > If the system was booted using a device tree and if the device tree
> > contains a MAC address, use it instead of reading one from the EEPROM.
> > This is useful in situations where the EEPROM isn't properly programmed
> > or where the firmware wants to override the existing MAC address.
> > 
> > Signed-off-by: Thierry Reding <[email-masked]>
> > ---
> > Based on net-next.
> > 
> >  drivers/net/ethernet/realtek/r8169.c | 35 +++++++++++++++++-----------
> >  1 file changed, 22 insertions(+), 13 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/realtek/r8169.c b/drivers/net/ethernet/realtek/r8169.c
> > index f574b6b557f9..fd9edd643ca5 100644
> > --- a/drivers/net/ethernet/realtek/r8169.c
> > +++ b/drivers/net/ethernet/realtek/r8169.c
> > @@ -6957,6 +6957,21 @@ static int rtl_alloc_irq(struct rtl8169_private *tp)
> >  	return pci_alloc_irq_vectors(tp->pci_dev, 1, 1, flags);
> >  }
> >  
> > +static void rtl_read_mac_address(struct rtl8169_private *tp,
> > +				 u8 mac_addr[ETH_ALEN])
> > +{
> > +	/* Get MAC address */
> > +	switch (tp->mac_version) {
> > +	case RTL_GIGA_MAC_VER_35 ... RTL_GIGA_MAC_VER_38:
> > +	case RTL_GIGA_MAC_VER_40 ... RTL_GIGA_MAC_VER_51:
> > +		*(u32 *)&mac_addr[0] = rtl_eri_read(tp, 0xe0, ERIAR_EXGMAC);
> > +		*(u16 *)&mac_addr[4] = rtl_eri_read(tp, 0xe4, ERIAR_EXGMAC);
> > +		break;
> > +	default:
> > +		break;
> > +	}
> > +}
> > +
> >  DECLARE_RTL_COND(rtl_link_list_ready_cond)
> >  {
> >  	return RTL_R8(tp, MCU) & LINK_LIST_RDY;
> > @@ -7148,6 +7163,7 @@ static int rtl_get_ether_clk(struct rtl8169_private *tp)
> >  static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
> >  {
> >  	const struct rtl_cfg_info *cfg = rtl_cfg_infos + ent->driver_data;
> > +	u8 mac_addr[ETH_ALEN] __aligned(4);
> 
> Hi Thierry
> 
> Maybe now would be a good time to cleanup this __aligned(4), pointer
> aliasing, etc?

Are you proposing that I rewrite rtl_read_mac_address() to manually
extract bytes from each register read? Something along these lines:

	value = rtl_eri_read(tp, 0xe0, ERIAR_EXGMAC);
	mac_addr[0] = (value >>  0) & 0xff;
	mac_addr[1] = (value >>  8) & 0xff;
	mac_addr[2] = (value >> 16) & 0xff;
	mac_addr[3] = (value >> 24) & 0xff;

	value = rtl_eri_read(tp, 0xe4 ERIAR_EXGMAC);
	mac_addr[4] = (value >>  0) & 0xff;
	mac_addr[5] = (value >>  8) & 0xff;

Looks like maybe that should be a separate patch?

> 
> > +	/* get MAC address */
> > +	if (eth_platform_get_mac_address(&pdev->dev, mac_addr))
> > +		rtl_read_mac_address(tp, mac_addr);
> > +
> 
> Maybe that could be made more readable with:
> 
>       err = eth_platform_get_mac_address(&pdev->dev, mac_addr);
>       if (err)
>       	 	rtl_read_mac_address(tp, mac_addr);

I was following the same pattern that other drivers were, but I can
change to the above if you prefer.

Thanks,
Thierry