From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geert Uytterhoeven Subject: Re: [PATCH v4.1] phylib: Add device reset GPIO support Date: Fri, 8 Dec 2017 10:53:26 +0100 Message-ID: References: <1512383692-14009-2-git-send-email-geert+renesas@glider.be> <1512390905-28094-1-git-send-email-geert+renesas@glider.be> <69fe9a6d-4039-6f80-b80d-7dc0de31e5bf@cogentembedded.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: <69fe9a6d-4039-6f80-b80d-7dc0de31e5bf@cogentembedded.com> Sender: linux-kernel-owner@vger.kernel.org To: Sergei Shtylyov Cc: Geert Uytterhoeven , "David S . Miller" , Andrew Lunn , Florian Fainelli , Simon Horman , Magnus Damm , Rob Herring , Mark Rutland , Nicolas Ferre , Richard Leitner , "netdev@vger.kernel.org" , "devicetree@vger.kernel.org" , Linux-Renesas , "linux-kernel@vger.kernel.org" List-Id: devicetree@vger.kernel.org Hi Sergei, On Thu, Dec 7, 2017 at 6:20 PM, Sergei Shtylyov wrote: > On 12/04/2017 03:35 PM, Geert Uytterhoeven wrote: >> From: Sergei Shtylyov >> The PHY devices sometimes do have their reset signal (maybe even power >> supply?) tied to some GPIO and sometimes it also does happen that a boot >> loader does not leave it deasserted. So far this issue has been attacked >> from (as I believe) a wrong angle: by teaching the MAC driver to >> manipulate >> the GPIO in question; that solution, when applied to the device trees, led >> to adding the PHY reset GPIO properties to the MAC device node, with one >> exception: Cadence MACB driver which could handle the "reset-gpios" prop >> in a PHY device subnode. I believe that the correct approach is to teach >> the 'phylib' to get the MDIO device reset GPIO from the device tree node >> corresponding to this device -- which this patch is doing... >> >> Note that I had to modify the AT803x PHY driver as it would stop working >> otherwise -- it made use of the reset GPIO for its own purposes... >> >> Signed-off-by: Sergei Shtylyov >> Acked-by: Rob Herring >> [geert: Propagate actual errors from fwnode_get_named_gpiod()] >> [geert: Avoid destroying initial setup] >> [geert: Consolidate GPIO descriptor acquiring code] >> Signed-off-by: Geert Uytterhoeven > > [...] >> >> diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c >> index 2df7b62c1a36811e..8f8b7747c54bc478 100644 >> --- a/drivers/net/phy/mdio_bus.c >> +++ b/drivers/net/phy/mdio_bus.c > > [...] >> >> @@ -48,9 +49,26 @@ >> int mdiobus_register_device(struct mdio_device *mdiodev) >> { >> + struct gpio_desc *gpiod = NULL; >> + >> if (mdiodev->bus->mdio_map[mdiodev->addr]) >> return -EBUSY; >> + /* Deassert the optional reset signal */ > > > Umm, but why deassert it here for such a short time? That's a consequence of moving it from drivers/of/of_mdio.c to here. Not that it was deasserted that much longer in drivers/of/of_mdio.c, though... 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