[v2] r8169: fix invalid register dump

From: Peter Wu <lekensteyn@gmail.com>

For some reason, my PCIe RTL8111E onboard NIC on a GA-Z68X-UD3H-B3
motherboard reads as FFs when reading from MMIO with a block size
larger than 7. Therefore change to reading blocks of four bytes.

Thanks to Francois for a better implementation.

Signed-off-by: Peter Wu <lekensteyn@gmail.com>
---
 drivers/net/ethernet/realtek/r8169.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

On Sat, 2013-08-17 at 11:04 +0200, Peter Wu wrote:
> From: Peter Wu <lekensteyn@gmail.com>
> 
> For some reason, my PCIe RTL8111E onboard NIC on a GA-Z68X-UD3H-B3
> motherboard reads as FFs when reading from MMIO with a block size
> larger than 7. Therefore change to reading blocks of four bytes.
> 
> Thanks to Francois for a better implementation.
> 
> Signed-off-by: Peter Wu <lekensteyn@gmail.com>
> ---
>  drivers/net/ethernet/realtek/r8169.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/realtek/r8169.c b/drivers/net/ethernet/realtek/r8169.c
> index b5eb419..2943916 100644
> --- a/drivers/net/ethernet/realtek/r8169.c
> +++ b/drivers/net/ethernet/realtek/r8169.c
> @@ -1897,12 +1897,16 @@ static void rtl8169_get_regs(struct net_device *dev, struct ethtool_regs *regs,
>  			     void *p)
>  {
>  	struct rtl8169_private *tp = netdev_priv(dev);
> +	u32 __iomem *data = tp->mmio_addr;
> +	u32 *dw = p;
> +	int i;
>  
>  	if (regs->len > R8169_REGS_SIZE)
>  		regs->len = R8169_REGS_SIZE;
>  
>  	rtl_lock_work(tp);
> -	memcpy_fromio(p, tp->mmio_addr, regs->len);
> +	for (i = regs->len; i > 0; i -= 4)
> +		memcpy_fromio(dw++, data++, min(4, i));

I would be very wary of accessing registers with any width other than
the usual (32 bits).

And as I said, the kernel buffer is always large enough for all your
registers, so this could just be:

	for (i = 0; i < R8169_REGS_SIZE; i += 4)
		memcpy_fromio(dw++, data++, 4);

Ben.

>  	rtl_unlock_work(tp);
>  }
>

Ben Hutchings <bhutchings@solarflare.com> :
[...]
> I would be very wary of accessing registers with any width other than
> the usual (32 bits).

You are right. Most registers do not seem to care - some are 8 bits
wide - but the 8168c datasheet states that it's out of spec for the
descriptor ring address registers.

Peter, please use Ben's suggestion as is.