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

Hi Heiner,

On Tue, Nov 27, 2018 at 8:47 PM Heiner Kallweit [off-list ref] wrote:

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?  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().

That's correct: my original motivation for picking up Sergei's patches was to
make Ethernet work after suspend/resume on the same Salvator-XS board.

The main difference seems to be that I was using NFS root, while Shimoda-san
is using an initramfs.  Hence there probably is an inconsistency in reset
handling for an active vs. inactive Ethernet interface.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds