From: Andrew Lunn <andrew@lunn.ch>
To: Mike Looijmans <mike.looijmans@topic.nl>
Cc: netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
Heiner Kallweit <hkallweit1@gmail.com>,
Jakub Kicinski <kuba@kernel.org>,
Russell King <linux@armlinux.org.uk>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: mdiobus: Prevent spike on MDIO bus reset signal
Date: Thu, 28 Jan 2021 02:56:25 +0100 [thread overview]
Message-ID: <YBIZyWZNoQeJ7Bt4@lunn.ch> (raw)
In-Reply-To: <20210126073337.20393-1-mike.looijmans@topic.nl>
On Tue, Jan 26, 2021 at 08:33:37AM +0100, Mike Looijmans wrote:
> The mdio_bus reset code first de-asserted the reset by allocating with
> GPIOD_OUT_LOW, then asserted and de-asserted again. In other words, if
> the reset signal defaulted to asserted, there'd be a short "spike"
> before the reset.
>
> Instead, directly assert the reset signal using GPIOD_OUT_HIGH, this
> removes the spike and also removes a line of code since the signal
> is already high.
Hi Mike
Did you look at the per PHY reset? mdiobus_register_gpiod() gets the
GPIO with GPIOD_OUT_LOW. mdiobus_register_device() then immediately
sets it high.
So it looks like it suffers from the same problem.
Andrew
next prev parent reply other threads:[~2021-01-28 1:57 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-26 7:33 [PATCH] net: mdiobus: Prevent spike on MDIO bus reset signal Mike Looijmans
2021-01-26 13:14 ` Andrew Lunn
2021-01-26 13:49 ` Russell King - ARM Linux admin
[not found] ` <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.949ef384-8293-46b8-903f-40a477c056ae.b4d05392-d8bb-4828-9ac6-5a63736d3625@emailsignatures365.codetwo.com>
[not found] ` <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.0d2bd5fa-15cc-4b27-b94e-83614f9e5b38.23e4b566-2e4d-4160-a40f-4bf79ef86f8a@emailsignatures365.codetwo.com>
2021-01-27 7:08 ` Mike Looijmans
2021-01-27 22:54 ` Jakub Kicinski
2021-01-28 0:00 ` Andrew Lunn
2021-01-28 0:25 ` Russell King - ARM Linux admin
2021-01-28 1:12 ` Andrew Lunn
[not found] ` <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.949ef384-8293-46b8-903f-40a477c056ae.47109184-a5be-4b1d-bb22-724baf83e536@emailsignatures365.codetwo.com>
[not found] ` <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.0d2bd5fa-15cc-4b27-b94e-83614f9e5b38.a2a17a1f-7cb0-46c3-bdd8-65266e08a153@emailsignatures365.codetwo.com>
2021-02-02 11:40 ` Mike Looijmans
2021-02-02 13:51 ` Andrew Lunn
2021-01-28 1:56 ` Andrew Lunn [this message]
[not found] ` <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.949ef384-8293-46b8-903f-40a477c056ae.7228ddf2-6794-42a0-8b0b-3821446cdb40@emailsignatures365.codetwo.com>
[not found] ` <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.0d2bd5fa-15cc-4b27-b94e-83614f9e5b38.7855d092-e2c3-4ba5-a029-2a0bbce637e1@emailsignatures365.codetwo.com>
2021-01-28 8:45 ` Mike Looijmans
2021-01-29 20:23 ` Andrew Lunn
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