Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753579AbdLGRks (ORCPT ); Thu, 7 Dec 2017 12:40:48 -0500 Received: from mail-lf0-f68.google.com ([209.85.215.68]:43094 "EHLO mail-lf0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753272AbdLGRkm (ORCPT ); Thu, 7 Dec 2017 12:40:42 -0500 X-Google-Smtp-Source: AGs4zMYAotQ3Vv3NwYwM2iNZ9j3c1fpgD2ToiX9YnAkyY/uYT/FmU9Rrj9eYOgT66i94EW/DS6zDmg== Subject: Re: [PATCH v4.1] phylib: Add device reset GPIO support From: Sergei Shtylyov To: Geert Uytterhoeven , "David S . Miller" , Andrew Lunn , Florian Fainelli , Simon Horman , Magnus Damm Cc: Rob Herring , Mark Rutland , Nicolas Ferre , Richard Leitner , netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-renesas-soc@vger.kernel.org, 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> Organization: Cogent Embedded Message-ID: <7019d8c1-4444-e981-b2fb-7fefde4a34be@cogentembedded.com> Date: Thu, 7 Dec 2017 20:40:37 +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: <69fe9a6d-4039-6f80-b80d-7dc0de31e5bf@cogentembedded.com> 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: 2356 Lines: 56 On 12/07/2017 08:20 PM, Sergei Shtylyov wrote: >> 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? > >> + if (mdiodev->dev.of_node) >> + gpiod = fwnode_get_named_gpiod(&mdiodev->dev.of_node->fwnode, >> + "reset-gpios", 0, GPIOD_OUT_LOW, >> + "PHY reset"); >> + if (PTR_ERR(gpiod) == -ENOENT) >> + gpiod = NULL; >> + else if (IS_ERR(gpiod)) >> + return PTR_ERR(gpiod); > > Hm, returning on error with reset deasserted? Oops, error means we couldn't drive the GPIO at all... The 1st question remains though... [...] MBR, Sergei