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From: Jerome Brunet <jbrunet@baylibre.com>
To: Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	netdev@vger.kernel.org, ingrassia@epigenesys.com
Cc: linus.luessing@c0d3.blue, khilman@baylibre.com,
	linux-amlogic@lists.infradead.org, narmstrong@baylibre.com,
	peppe.cavallaro@st.com, alexandre.torgue@st.com
Subject: Re: [RFT net-next 2/2] net: stmmac: dwmac-meson8b: don't try to change m250_div parent's rate
Date: Sat, 23 Dec 2017 18:43:24 +0100	[thread overview]
Message-ID: <1514051004.29566.55.camel@baylibre.com> (raw)
In-Reply-To: <1514050857.29566.53.camel@baylibre.com>

On Sat, 2017-12-23 at 18:40 +0100, Jerome Brunet wrote:
> > Trying to set the rate of m250_div's parent clock makes no sense since
> > it's a mux which has neither CLK_MUX_ROUND_CLOSEST nor
> > CLK_SET_RATE_PARENT set.
> > It even does harm on Meson8b SoCs where the input clock for the mux
> > cannot be divided down to 250MHz evenly (the parent rate is 500002394Hz)
> 
> So your problem is more with the mux actually, not the divider. Instead of
> removing CLK_SET_RATE_PARENT from the divider, may I suggest to put
> 
> CLK_SET_RATE_PARENT | CLK_SET_RATE_NO_REPARENT on the parent mux, and keep

Thinking about it, you don't even need CLK_SET_RATE_NO_REPARENT. Just let rate
propagation figure out the best combination 

> CLK_SET_RATE_PARENT (with CLK_DIVIDER_ROUND_CLOSEST)  on the divS.
> 
> I suppose it would a accomplish the same thing with one added benefits for
> meson8b :
> 
> If the bootloader did not set the mpll2 to the correct rate, it will now be done
> thanks to rate propagation.
> 
> If I missed anything, feel free to point it out.
> 
> Cheers 

  reply	other threads:[~2017-12-23 17:43 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-23 17:04 [RFT net-next 0/2] dwmac-meson8b: clock rounding fixes for Meson8b Martin Blumenstingl
2017-12-23 17:04 ` [RFT net-next 1/2] net: stmmac: dwmac-meson8b: fix setting the PHY clock on Meson8b Martin Blumenstingl
2017-12-23 17:32   ` Jerome Brunet
2017-12-23 17:04 ` [RFT net-next 2/2] net: stmmac: dwmac-meson8b: don't try to change m250_div parent's rate Martin Blumenstingl
2017-12-23 17:40   ` Jerome Brunet
2017-12-23 17:43     ` Jerome Brunet [this message]
2017-12-23 20:00     ` Martin Blumenstingl
2017-12-23 20:40       ` Jerome Brunet
2017-12-23 21:49         ` Martin Blumenstingl
2017-12-23 22:41           ` Jerome Brunet
2017-12-23 23:12             ` Martin Blumenstingl

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