RE: [PATCH/RFC] net: phy: device: Don't deassert the reset when register and probe

Hi Heiner,

From: Heiner Kallwei, Sent: Wednesday, November 28, 2018 4:46 AM

On 27.11.2018 17:44, Andrew Lunn wrote:

quoted

On Tue, Nov 27, 2018 at 12:18:20PM +0000, Yoshihiro Shimoda wrote:

quoted

Some PHY device needs edge signal of the reset, but the previous code
is impossible to achieve it like following:

 1) Kernel boots by using initramfs.
 --> No open the nic, so the provious code deasserts the reset by
     phy_device_register() and phy_probe().
 2) Kernel enters the suspend.
 --> So, keep the reset signal as deassert.
 --> On R-Car Salvator-XS board, unfortunately, the board power is
     turned off.
 3) Kernel returns from suspend.
 4) ifconfig eth0 up
 --> Then, since edge signal of the reset doesn't happen,
     it cannot link up.

Hi Yoshihiro

It sounds like you should be adding code to the suspend/resume
handling of phylib, so that it toggle the reset on resume. You cannot
just delete code like you proposed, it is going to break devices. But
adding code should be O.K.

The commit message mentions that the patch is supposed to fix some
issue on the Salvator-XS board. I found the following from a year ago
https://www.spinics.net/lists/netdev/msg457308.html
which is also about PHY reset and this board. Is there still something
open?

Thank you for your comment!
As Geert mentioned on this email thread, that patch can handle if user opened
the NIC and then the PHY was active.

 But as Andrew mentioned already: Just deleting code w/o
checking what it's good for and whether this could have side effects,
isn't a solution. Especially because the patch would silently remove
the call to phy_scan_fixups().

I should have mentioned on the commit log, but phy_scan_fixups() is called
by phy_init_hw() and phy_init_hw() is called phy_attach_direct(). So,
I think we can remove phy_scan_fixups(). However, as you mentioned,
this patch could have side effects...

So, I'll make such a suspend/resume patch that Andrew mentioned later.

Best regards,
Yoshihiro Shimoda