Re: [Intel-wired-lan] [PATCH linux-next] e1000: Remove redundant statement

Apologies for the duplicates, mail from my intel account going out
through outlook.com is not being delivered.

On Wed, Oct 20, 2021 at 7:00 AM Simon Horman [off-list ref] wrote:

quoted

Value stored to 'ctrl_reg' is never read.

I agree this does seem to be the case.

quoted

Reported-by: Zeal Robot <redacted>
Signed-off-by: luo penghao <redacted>

Reviewed-by: Simon Horman <horms@kernel.org>

Thanks for the review, but (davem/kuba) please do not apply.

quoted

@@ -1215,8 +1215,6 @@ static int e1000_integrated_phy_loopback(struct e1000_adapter *adapter)
              e1000_write_phy_reg(hw, PHY_CTRL, 0x8140);
      }

-     ctrl_reg = er32(CTRL);

Thanks for your patch, but this change is not safe. you're removing a
read that could do two things. The first is that the read "flushes"
the write just above to PCI (it's a PCI barrier), and the second is
that the read can have some side effects.

If this change must be done, the code should be to remove the
assignment to ctrl_reg, but leave the read, so the line would just
look like:
        er32(CTRL);

This will get rid of the warning and not change the flow from the
hardware perspective.

quoted

-
      /* force 1000, set loopback */
      e1000_write_phy_reg(hw, PHY_CTRL, 0x4140);

Please do not apply this.