From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751229AbeDYBJL (ORCPT ); Tue, 24 Apr 2018 21:09:11 -0400 Received: from mail-qt0-f193.google.com ([209.85.216.193]:47070 "EHLO mail-qt0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750756AbeDYBJG (ORCPT ); Tue, 24 Apr 2018 21:09:06 -0400 X-Google-Smtp-Source: AB8JxZoL4oNqAyLjF0XJgfDqHxvEbdzl3Z4HOcprwDUt8qvn3Ar/c2FZQ7P2JRiPIp3KtBBJkxg8/w== Subject: Re: [PATCH] net: phy: allow scanning busses with missing phys To: Andrew Lunn Cc: Alexandre Belloni , "David S . Miller" , Allan Nielsen , Thomas Petazzoni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20180424160904.32457-1-alexandre.belloni@bootlin.com> <2833f30a-cf95-e5c7-e44f-218929e61024@gmail.com> <20180424180153.GD2360@lunn.ch> From: Florian Fainelli Openpgp: preference=signencrypt Autocrypt: addr=f.fainelli@gmail.com; prefer-encrypt=mutual; keydata= xsDiBEjPuBIRBACW9MxSJU9fvEOCTnRNqG/13rAGsj+vJqontvoDSNxRgmafP8d3nesnqPyR xGlkaOSDuu09rxuW+69Y2f1TzjFuGpBk4ysWOR85O2Nx8AJ6fYGCoeTbovrNlGT1M9obSFGQ X3IzRnWoqlfudjTO5TKoqkbOgpYqIo5n1QbEjCCwCwCg3DOH/4ug2AUUlcIT9/l3pGvoRJ0E AICDzi3l7pmC5IWn2n1mvP5247urtHFs/uusE827DDj3K8Upn2vYiOFMBhGsxAk6YKV6IP0d ZdWX6fqkJJlu9cSDvWtO1hXeHIfQIE/xcqvlRH783KrihLcsmnBqOiS6rJDO2x1eAgC8meAX SAgsrBhcgGl2Rl5gh/jkeA5ykwbxA/9u1eEuL70Qzt5APJmqVXR+kWvrqdBVPoUNy/tQ8mYc nzJJ63ng3tHhnwHXZOu8hL4nqwlYHRa9eeglXYhBqja4ZvIvCEqSmEukfivk+DlIgVoOAJbh qIWgvr3SIEuR6ayY3f5j0f2ejUMYlYYnKdiHXFlF9uXm1ELrb0YX4GMHz80nRmxvcmlhbiBG YWluZWxsaSA8Zi5mYWluZWxsaUBnbWFpbC5jb20+wmYEExECACYCGyMGCwkIBwMCBBUCCAME FgIDAQIeAQIXgAUCVF/S8QUJHlwd3wAKCRBhV5kVtWN2DvCVAJ4u4/bPF4P3jxb4qEY8I2gS 6hG0gACffNWlqJ2T4wSSn+3o7CCZNd7SLSDOw00ESM+4EhAQAL/o09boR9D3Vk1Tt7+gpYr3 WQ6hgYVON905q2ndEoA2J0dQxJNRw3snabHDDzQBAcqOvdi7YidfBVdKi0wxHhSuRBfuOppu pdXkb7zxuPQuSveCLqqZWRQ+Cc2QgF7SBqgznbe6Ngout5qXY5Dcagk9LqFNGhJQzUGHAsIs hap1f0B1PoUyUNeEInV98D8Xd/edM3mhO9nRpUXRK9Bvt4iEZUXGuVtZLT52nK6Wv2EZ1TiT OiqZlf1P+vxYLBx9eKmabPdm3yjalhY8yr1S1vL0gSA/C6W1o/TowdieF1rWN/MYHlkpyj9c Rpc281gAO0AP3V1G00YzBEdYyi0gaJbCEQnq8Vz1vDXFxHzyhgGz7umBsVKmYwZgA8DrrB0M oaP35wuGR3RJcaG30AnJpEDkBYHznI2apxdcuTPOHZyEilIRrBGzDwGtAhldzlBoBwE3Z3MY 31TOpACu1ZpNOMysZ6xiE35pWkwc0KYm4hJA5GFfmWSN6DniimW3pmdDIiw4Ifcx8b3mFrRO BbDIW13E51j9RjbO/nAaK9ndZ5LRO1B/8Fwat7bLzmsCiEXOJY7NNpIEpkoNoEUfCcZwmLrU +eOTPzaF6drw6ayewEi5yzPg3TAT6FV3oBsNg3xlwU0gPK3v6gYPX5w9+ovPZ1/qqNfOrbsE FRuiSVsZQ5s3AAMFD/9XjlnnVDh9GX/r/6hjmr4U9tEsM+VQXaVXqZuHKaSmojOLUCP/YVQo 7IiYaNssCS4FCPe4yrL4FJJfJAsbeyDykMN7wAnBcOkbZ9BPJPNCbqU6dowLOiy8AuTYQ48m vIyQ4Ijnb6GTrtxIUDQeOBNuQC/gyyx3nbL/lVlHbxr4tb6YkhkO6shjXhQh7nQb33FjGO4P WU11Nr9i/qoV8QCo12MQEo244RRA6VMud06y/E449rWZFSTwGqb0FS0seTcYNvxt8PB2izX+ HZA8SL54j479ubxhfuoTu5nXdtFYFj5Lj5x34LKPx7MpgAmj0H7SDhpFWF2FzcC1bjiW9mjW HaKaX23Awt97AqQZXegbfkJwX2Y53ufq8Np3e1542lh3/mpiGSilCsaTahEGrHK+lIusl6mz Joil+u3k01ofvJMK0ZdzGUZ/aPMZ16LofjFA+MNxWrZFrkYmiGdv+LG45zSlZyIvzSiG2lKy kuVag+IijCIom78P9jRtB1q1Q5lwZp2TLAJlz92DmFwBg1hyFzwDADjZ2nrDxKUiybXIgZp9 aU2d++ptEGCVJOfEW4qpWCCLPbOT7XBr+g/4H3qWbs3j/cDDq7LuVYIe+wchy/iXEJaQVeTC y5arMQorqTFWlEOgRA8OP47L9knl9i4xuR0euV6DChDrguup2aJVU8JPBBgRAgAPAhsMBQJU X9LxBQkeXB3fAAoJEGFXmRW1Y3YOj4UAn3nrFLPZekMeqX5aD/aq/dsbXSfyAKC45Go0YyxV HGuUuzv+GKZ6nsysJw== Message-ID: <587d8151-34a7-d771-2a14-a7259d6c1855@gmail.com> Date: Tue, 24 Apr 2018 18:08:57 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180424180153.GD2360@lunn.ch> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/24/2018 11:01 AM, Andrew Lunn wrote: > On Tue, Apr 24, 2018 at 09:37:09AM -0700, Florian Fainelli wrote: >> >> >> On 04/24/2018 09:09 AM, Alexandre Belloni wrote: >>> Some MDIO busses will error out when trying to read a phy address with no >>> phy present at that address. In that case, probing the bus will fail >>> because __mdiobus_register() is scanning the bus for all possible phys >>> addresses. >>> >>> In case MII_PHYSID1 returns -EIO or -ENODEV, consider there is no phy at >>> this address and set the phy ID to 0xffffffff which is then properly >>> handled in get_phy_device(). >> >> Humm, why not have your MDIO bus implementation do the scanning itself >> in a reset() callback, which happens before probing the bus, and based >> on the results, set phy_mask accordingly such that only PHYs present are >> populated? > > Hi Florian > > Seems a bit odd have the driver do this, when the core could. I could see arguments for doing it in either location, if this is done in the driver, the driver is responsible for knowing what addresses will respond, which does not seem to big of a stretch. If done by core, we lift the driver from taking care of that. Either way is fine, really. > >> My only concern with your change is that we are having a special >> treatment for EIO and ENODEV, so we must make sure MDIO bus drivers are >> all conforming to that. > > I don't see how it could be a problem. It used to be any error was a > real error, and would stop the bus from loading. It now means there is > nothing there. The only possible side effect is an mdio bus driver > might remain loaded without any devices if all reads return > ENODEV/EIO, were as before it would probably never load. Right, though that does not seem to be a big problem. > > Andrew > -- Florian