Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752379AbdLHRUS (ORCPT ); Fri, 8 Dec 2017 12:20:18 -0500 Received: from mail-lf0-f65.google.com ([209.85.215.65]:38197 "EHLO mail-lf0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751243AbdLHRUO (ORCPT ); Fri, 8 Dec 2017 12:20:14 -0500 X-Google-Smtp-Source: AGs4zMYzWR5bfweM/ovBK+5nA7uYLmdyVEd/HUzQP3Na9ousf3ULnb+RL+gcdYeDFBzYQ+hskONruw== Subject: Re: [PATCH v4.1] phylib: Add device reset GPIO support To: Geert Uytterhoeven 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" 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> From: Sergei Shtylyov Organization: Cogent Embedded Message-ID: <837cb555-f747-e8a8-ac1a-aa25ad213c0a@cogentembedded.com> Date: Fri, 8 Dec 2017 20:20:09 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-MW Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2534 Lines: 64 Hello! On 12/08/2017 12:53 PM, Geert Uytterhoeven 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. Well, you shouldn't do code moves without some thinking. ;-) > Not that it was deasserted that much longer in drivers/of/of_mdio.c, though... There it had a reason, here I'm not seeing one. Perhaps using GPIOD_ASIS (or GPIOD_OUT_HIGH) instead of GPIOD_OUT_LOW and dropping mdio_device_reset(mdiodev, 1) afterwards would make more sense here? > Gr{oetje,eeting}s, > > Geert MBR, Sergei