From: Marek Vasut <marex@denx.de>
To: George McCollister <george.mccollister@gmail.com>
Cc: netdev@vger.kernel.org, Andrew Lunn <andrew@lunn.ch>,
"David S . Miller" <davem@davemloft.net>,
Florian Fainelli <f.fainelli@gmail.com>,
Tristram Ha <Tristram.Ha@microchip.com>,
Vivien Didelot <vivien.didelot@savoirfairelinux.com>,
Woojung Huh <woojung.huh@microchip.com>
Subject: Re: [PATCH V2] net: dsa: microchip: Always set regmap stride to 1
Date: Sat, 28 Sep 2019 03:56:25 +0200 [thread overview]
Message-ID: <638f42ee-bb8e-0217-df09-665ddd795ad5@denx.de> (raw)
In-Reply-To: <CAFSKS=PFBewpMiMXuPmJXqv=sbYhS8_9k=DrwAXjjPNi7xFwcA@mail.gmail.com>
On 9/26/19 3:52 PM, George McCollister wrote:
> On Wed, Sep 25, 2019 at 5:08 PM Marek Vasut wrote:
>>
>> The regmap stride is set to 1 for regmap describing 8bit registers already.
>> However, for 16/32/64bit registers, the stride is 2/4/8 respectively. This
>> is not correct, as the switch protocol supports unaligned register reads
>> and writes and the KSZ87xx even uses such unaligned register accesses to
>> read e.g. MIB counter.
>>
>> This patch fixes MIB counter access on KSZ87xx.
>
> After looking through a couple hundred pages of register documentation
> for KSZ9477 and KSZ9567 I find only registers that are aligned to
> their width. In my testing the KSZ9567 works fine with and without the
> patch. The only downside is that all of the unaligned registers
> needlessly show up in the debugfs regmap, this doesn't really matter
> though. As long as it fixes the issues on KSZ87xx this looks fine to
> me.
Right.
To avoid exposing all registers through regmap debugfs entries, we would
have to define the regmap constrains for
readable/writeable/volatile/precious registers, which we should
eventually do anyway, but that's way beyond the scope of this fix.
next prev parent reply other threads:[~2019-09-28 1:56 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-25 22:08 [PATCH V2] net: dsa: microchip: Always set regmap stride to 1 Marek Vasut
2019-09-26 13:52 ` George McCollister
2019-09-28 1:56 ` Marek Vasut [this message]
2019-09-27 18:21 ` David Miller
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