From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1519CC433E0 for ; Mon, 25 May 2020 03:34:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ECB06207DA for ; Mon, 25 May 2020 03:34:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388747AbgEYDeP (ORCPT ); Sun, 24 May 2020 23:34:15 -0400 Received: from foss.arm.com ([217.140.110.172]:35314 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388397AbgEYDeO (ORCPT ); Sun, 24 May 2020 23:34:14 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E00FC31B; Sun, 24 May 2020 20:34:13 -0700 (PDT) Received: from [192.168.122.166] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8FF6D3F305; Sun, 24 May 2020 20:34:13 -0700 (PDT) Subject: Re: [RFC 04/11] net: phy: Handle c22 regs presence better To: Russell King - ARM Linux admin Cc: netdev@vger.kernel.org, davem@davemloft.net, andrew@lunn.ch, f.fainelli@gmail.com, hkallweit1@gmail.com, madalin.bucur@oss.nxp.com, calvin.johnson@oss.nxp.com, linux-kernel@vger.kernel.org References: <20200522213059.1535892-1-jeremy.linton@arm.com> <20200522213059.1535892-5-jeremy.linton@arm.com> <20200523183731.GZ1551@shell.armlinux.org.uk> From: Jeremy Linton Message-ID: Date: Sun, 24 May 2020 22:34:13 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200523183731.GZ1551@shell.armlinux.org.uk> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 5/23/20 1:37 PM, Russell King - ARM Linux admin wrote: > On Fri, May 22, 2020 at 04:30:52PM -0500, Jeremy Linton wrote: >> Until this point, we have been sanitizing the c22 >> regs presence bit out of all the MMD device lists. >> This is incorrect as it causes the 0xFFFFFFFF checks >> to incorrectly fail. Further, it turns out that we >> want to utilize this flag to make a determination that >> there is actually a phy at this location and we should >> be accessing it using c22. >> >> Signed-off-by: Jeremy Linton >> --- >> drivers/net/phy/phy_device.c | 16 +++++++++++++--- >> 1 file changed, 13 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c >> index f0761fa5e40b..2d677490ecab 100644 >> --- a/drivers/net/phy/phy_device.c >> +++ b/drivers/net/phy/phy_device.c >> @@ -689,9 +689,6 @@ static int get_phy_c45_devs_in_pkg(struct mii_bus *bus, int addr, int dev_addr, >> return -EIO; >> *devices_in_package |= phy_reg; >> >> - /* Bit 0 doesn't represent a device, it indicates c22 regs presence */ >> - *devices_in_package &= ~BIT(0); >> - >> return 0; >> } >> >> @@ -742,6 +739,8 @@ static int get_phy_c45_ids(struct mii_bus *bus, int addr, u32 *phy_id, >> int i; >> const int num_ids = ARRAY_SIZE(c45_ids->device_ids); >> u32 *devs = &c45_ids->devices_in_package; >> + bool c22_present = false; >> + bool valid_id = false; >> >> /* Find first non-zero Devices In package. Device zero is reserved >> * for 802.3 c45 complied PHYs, so don't probe it at first. >> @@ -770,6 +769,10 @@ static int get_phy_c45_ids(struct mii_bus *bus, int addr, u32 *phy_id, >> return 0; >> } >> >> + /* Bit 0 doesn't represent a device, it indicates c22 regs presence */ >> + c22_present = *devs & BIT(0); >> + *devs &= ~BIT(0); >> + >> /* Now probe Device Identifiers for each device present. */ >> for (i = 1; i < num_ids; i++) { >> if (!(c45_ids->devices_in_package & (1 << i))) >> @@ -778,6 +781,13 @@ static int get_phy_c45_ids(struct mii_bus *bus, int addr, u32 *phy_id, >> ret = _get_phy_id(bus, addr, i, &c45_ids->device_ids[i], true); >> if (ret < 0) >> return ret; >> + if (valid_phy_id(c45_ids->device_ids[i])) >> + valid_id = true; > > Here you are using your "devices in package" validator to validate the > PHY ID value. One of the things it does is mask this value with > 0x1fffffff. That means you lose some of the vendor OUI. To me, this > looks completely wrong. I think in this case I was just using it like the comment in get_phy_device() "if the phy_id is mostly F's, there is no device here". My understanding is that the code is trying to avoid the 0xFFFFFFFF returns that seem to indicate "bus ok, phy didn't respond". I just checked the OUI registration, and while there are a couple OUI's registered that have a number of FFF's in them, none of those cases seems to overlap sufficiently to cause this to throw them out. Plus a phy would also have to have model+revision set to 'F's. So while might be possible, if unlikely, at the moment I think the OUI registration keeps this from being a problem. Particularly, if i'm reading the mapping correctly, the OUI mapping guarantees that the field cannot be all '1's due to the OUI having X & M bits cleared. It sort of looks like the mapping is trying to lose those bits, by tossing bit 1 & 2, but the X & M are in the wrong octet (AFAIK, I just read it three times cause it didn't make any sense).