[PATCH 2/2] ARM: dts: imx6qdl-microsom-ar8035: Adjust Ethernet PHY reset duration

On Mon, Jan 4, 2016 at 8:42 PM, Russell King - ARM Linux
[off-list ref] wrote:

On Mon, Jan 04, 2016 at 05:11:40PM -0200, Fabio Estevam wrote:

quoted

From: Fabio Estevam <redacted>

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.