Re: [PATCH 1/2] Revert commit 1b0a83ac04e383e3bed21332962b90710fcf2828

[Andrew Lunn <andrew@lunn.ch>]

On Wed, Apr 29, 2020 at 09:03:32AM +0000, Badel, Laurent wrote:
> Description: This patch reverts commit 1b0a83ac04e3 
> ("net: fec: add phy_reset_after_clk_enable() support")
> which produces undesirable behavior when PHY interrupts are enabled.
> 
> Rationale: the SMSC LAN8720 (and possibly other chips) is known
> to require a reset after the external clock is enabled. Calls to
> phy_reset_after_clk_enable() in fec_main.c have been introduced in 
> commit 1b0a83ac04e3 ("net: fec: add phy_reset_after_clk_enable() support")
> to handle the chip reset after enabling the clock.
> However, this breaks when interrupts are enabled because
> the reset reverts the configuration of the PHY interrupt mask to default
> (in addition it also reverts the "energy detect" mode setting).
> As a result the driver does not receive the link status change
> and other notifications resulting in loss of connectivity. 
> 
> Proposed solution: revert commit 1b0a83ac04e3 and bring the reset 
> before the PHY configuration by adding it to phy_init_hw() [phy_device.c].
> 
> Test results: using an iMX28-EVK-based board, these 2 patches successfully
> restore network interface functionality when interrupts are enabled.
> Tested using both linux-5.4.23 and latest mainline (5.6.0) kernels.
> 
> Fixes: 1b0a83ac04e383e3bed21332962b90710fcf2828 ("net: fec: add phy_reset_after_clk_enable() support")
> Signed-off-by: Laurent Badel <laurentbadel@eaton.com>

Hi Laurent

Please also read https://www.kernel.org/doc/Documentation/networking/netdev-FAQ.txt

       Andrew