netdev - Re: [PATCH 1/2] net: dsa: bcm_sf2: add function finding RGMII register

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Message-ID: <e42f1076-7f4a-574a-bce9-726b1b402a9f@gmail.com>
Date:   Thu, 18 Mar 2021 09:16:17 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Rafał Miłecki <zajec5@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Vladimir Oltean <olteanv@...il.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        bcm-kernel-feedback-list@...adcom.com,
        Rafał Miłecki <rafal@...ecki.pl>
Subject: Re: [PATCH 1/2] net: dsa: bcm_sf2: add function finding RGMII
 register



On 3/18/2021 12:30 AM, Rafał Miłecki wrote:
> On 17.03.2021 22:20, Florian Fainelli wrote:
>> On 3/17/2021 7:37 AM, Rafał Miłecki wrote:
>>> From: Rafał Miłecki <rafal@...ecki.pl>
>>>
>>> Simple macro like REG_RGMII_CNTRL_P() is insufficient as:
>>> 1. It doesn't validate port argument
>>> 2. It doesn't support chipsets with non-lineral RGMII regs layout
>>>
>>> Missing port validation could result in getting register offset from out
>>> of array. Random memory -> random offset -> random reads/writes. It
>>> affected e.g. BCM4908 for REG_RGMII_CNTRL_P(7).
>>
>> That is entirely fair, however as a bug fix this is not necessarily the
>> simplest way to approach this.
> 
> I'm not sure if I understand. Should I fix it in some totally different
> way? Or should I just follow your inline suggestions?

What I meant is that for a bug fix you could just mangled the offset of
the register such that REG_RGMII_CNTRL_P(7) would resole to the right
offset. That would be lying a little bit, but for a bug fix, that would
work. Not that it matters since the changes are still fresh in net/net-next.
-- 
Florian