All of lore.kernel.org
 help / color / mirror / Atom feed
From: festevam@gmail.com (Fabio Estevam)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/2] ARM: dts: imx6qdl-microsom-ar8035: Adjust Ethernet PHY reset duration
Date: Tue, 5 Jan 2016 10:23:37 -0200	[thread overview]
Message-ID: <CAOMZO5ByFwYk7JT=U-y-ECpDHLXwwk3XSiRWpsini2E34qmLbA@mail.gmail.com> (raw)
In-Reply-To: <20160104224234.GR19062@n2100.arm.linux.org.uk>

On Mon, Jan 4, 2016 at 8:42 PM, Russell King - ARM Linux
<linux@arm.linux.org.uk> wrote:
> On Mon, Jan 04, 2016 at 05:11:40PM -0200, Fabio Estevam wrote:
>> From: Fabio Estevam <fabio.estevam@nxp.com>
>>
>> As per the AR8035 datasheet:
>>
>> "For a reliable power on reset, suggest to keep asserting the reset
>> low long enough (10ms) to ensure the clock is stable and clock-to-reset
>> 1ms requirement is satisfied."
>
> This is questionable.  The quote you indicate above is "For a reliable
> POWER ON RESET".  It depends what use this DT is being put to.  Given
> that the only boot loader which is trustworthy on SoldRun hardware is
> their uboot versions, and these don't use DT, I would say that the
> only time that this is used is when the kernel is booting.
>
> That reset is not a power on reset, the phy has been powered for a
> comparitively long time by the time the kernel gets to use it.  So, I
> think on balance I'm going to NAK this change until there is a reason
> for it to be made - iow, when there _is_ a boot loader where the
> requirement for this parameter to be used at power on is required.

Ok, understood. I was working on a fix for U-boot where the 2ms reset
was not enough, so I thought about extending it to the kernel. I see
your point and agree that for the kernel we could keep the existing
2ms reset delay.

      reply	other threads:[~2016-01-05 12:23 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-04 19:11 [PATCH 1/2] ARM: dts: imx6qdl-sabresd: Pass 'phy-reset-duration' property Fabio Estevam
2016-01-04 19:11 ` [PATCH 2/2] ARM: dts: imx6qdl-microsom-ar8035: Adjust Ethernet PHY reset duration Fabio Estevam
2016-01-04 22:42   ` Russell King - ARM Linux
2016-01-05 12:23     ` Fabio Estevam [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAOMZO5ByFwYk7JT=U-y-ECpDHLXwwk3XSiRWpsini2E34qmLbA@mail.gmail.com' \
    --to=festevam@gmail.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.