From: Andrey Smirnov <andrew.smirnov@gmail.com>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: "barebox@lists.infradead.org" <barebox@lists.infradead.org>
Subject: Re: [PATCH 7/7] commands: Add mdio_read and mdio_write
Date: Tue, 26 Jan 2016 18:09:00 -0800 [thread overview]
Message-ID: <CAHQ1cqEemyC0CfVQeshBuJtA1p0mCQaPB33noov4N7FSk5F+Ng@mail.gmail.com> (raw)
In-Reply-To: <20160126215555.GD13058@pengutronix.de>
On Tue, Jan 26, 2016 at 1:55 PM, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> On Mon, Jan 25, 2016 at 09:55:58PM -0800, Andrey Smirnov wrote:
>> Add commands for low-level access to MDIO bus.
>
> Do we really need this? We can already read/write phy registers using
> /dev/phyx which imo is quite convenient since it can be accessed with
> regular md/mw commands.
>
> This of course is currently limited to the phys that are actually
> registered, you can't just bang on MDIO addresses on which no phys are
> registered. Maybe we could register all phys on a MDIO bus instead of
> only the used ones?
Just to explain the purpose of this patch -- there are number of
reasons we might want to be able to access "unregistered" PHYs:
- Not all MDIO attached devices would have PHYSID1,2 registers
available which might cause mdiobus_scan() to not detect those PHYs
- MDIO bus troubleshooting
As for registering all PHYs on a bus, correct me if I am wrong but
that would result in 32*N number of entries in /dev, where N is number
of MDIO buses in the system. The device I am working with right now
has 3 MDIO buses which would mean that I'd end up with 96 additional
entries in /dev, which might be a little bit overwhelming from UI
point of view. The other UI problem with that approach is that
/dev/phy's are numbered linearly so in order to figure out how to
access device on bus N at address M, user would have to perform N*32 +
M in their head.
Andrey
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next prev parent reply other threads:[~2016-01-27 2:09 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-26 5:55 [PATCH 1/7] include/linux/phy.h: Add MII_ADDR_C45 Andrey Smirnov
2016-01-26 5:55 ` [PATCH 2/7] net: Port bitbanged MDIO code from Linux kernel Andrey Smirnov
2016-01-26 5:55 ` [PATCH 3/7] miitool: Fix PHY argument handling Andrey Smirnov
2016-01-26 5:55 ` [PATCH 4/7] mdio_bus: Change dev_info to dev_dbg Andrey Smirnov
2016-01-26 5:55 ` [PATCH 5/7] mdio_bus: Add mdiobus_get_bus() function Andrey Smirnov
2016-01-26 5:55 ` [PATCH 6/7] miitool: Don't print negative parent IDs Andrey Smirnov
2016-01-26 5:55 ` [PATCH 7/7] commands: Add mdio_read and mdio_write Andrey Smirnov
2016-01-26 21:55 ` Sascha Hauer
2016-01-27 2:09 ` Andrey Smirnov [this message]
2016-01-27 2:29 ` Trent Piepho
2016-01-27 7:19 ` Sascha Hauer
2016-01-27 7:26 ` Sascha Hauer
2016-01-28 18:00 ` Andrey Smirnov
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