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From: Jerome Brunet <jbrunet@baylibre.com>
To: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: devicetree@vger.kernel.org,
	Neil Armstrong <narmstrong@baylibre.com>,
	khilman@baylibre.com, linux-kernel@vger.kernel.org,
	linux-amlogic@lists.infradead.org, linux-clk@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 0/6] add the DDR clock controller on Meson8 and Meson8b
Date: Tue, 01 Oct 2019 15:33:04 +0200	[thread overview]
Message-ID: <1jeezwr3ov.fsf@starbuckisacylon.baylibre.com> (raw)
In-Reply-To: <CAFBinCAHD+D=a2mHeHMGq12MvoksHBr308jSrdcH+UYsUmwd8w@mail.gmail.com>


On Mon 23 Sep 2019 at 22:49, Martin Blumenstingl <martin.blumenstingl@googlemail.com> wrote:

> Hi Jerome,
>
> On Mon, Sep 23, 2019 at 12:06 PM Jerome Brunet <jbrunet@baylibre.com> wrote:
>>
>> On Sat 21 Sep 2019 at 17:18, Martin Blumenstingl <martin.blumenstingl@googlemail.com> wrote:
>>
>> > Meson8 and Meson8b SoCs embed a DDR clock controller in their MMCBUS
>> > registers. This series:
>> > - adds support for this DDR clock controller (patches 0 and 1)
>> > - wires up the DDR PLL as input for two audio clocks (patches 2 and 3)
>>
>> Have you been able to validate somehow that DDR rate calculated by CCF
>> is the actual rate that gets to the audio clocks ?
> no, I haven't been able to validate this (yet)
>
>> While I understand the interest for completeness, I suspect the having
>> the DDR clock as an audio parent was just for debugging purpose. IOW,
>> I'm not sure if adding this parent is useful to an actual audio use
>> case. As far as audio would be concerned, I think we are better of
>> without this parent.
> there at least three other (potential) consumers of the ddr_pll clocks
> on the 32-bit SoCs:
> - CPU clock mux [0]
> - clk81 mux [1]
> - USB PHY [2]
>
> I have not validated any of these either
>

Then I would suggest to leave patch 4 out until we can somehow validate
this. 

>
>
> Martin
>
>
> [0] https://github.com/endlessm/u-boot-meson/blob/345ee7eb02903f5ecb1173ffb2cd36666e44ebed/board/amlogic/m8b_m201_v1/firmware/timming.c#L441
> [1] https://github.com/endlessm/u-boot-meson/blob/345ee7eb02903f5ecb1173ffb2cd36666e44ebed/board/amlogic/m8b_m201_v1/firmware/timming.c#L452
> [2] https://github.com/endlessm/u-boot-meson/blob/f1ee03e3f7547d03e1478cc1fc967a9e5a121d92/arch/arm/cpu/aml_meson/m8/firmware/usb_boot/platform.c#L22


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      reply	other threads:[~2019-10-01 13:33 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-21 15:18 [PATCH 0/6] add the DDR clock controller on Meson8 and Meson8b Martin Blumenstingl
2019-09-21 15:18 ` [PATCH 1/6] dt-bindings: clock: add the Amlogic Meson8 DDR clock controller binding Martin Blumenstingl
2019-10-02 14:19   ` Rob Herring
2019-09-21 15:18 ` [PATCH 2/6] clk: meson: add a driver for the Meson8/8b/8m2 DDR clock controller Martin Blumenstingl
2019-10-01 13:29   ` Jerome Brunet
2019-10-01 18:53     ` Martin Blumenstingl
2019-10-02  9:04       ` Jerome Brunet
2019-09-21 15:18 ` [PATCH 3/6] clk: meson: meson8b: use of_clk_hw_register to register the clocks Martin Blumenstingl
2019-09-21 15:18 ` [PATCH 4/6] clk: meson: meson8b: add the ddr_pll input for the audio clocks Martin Blumenstingl
2019-09-21 15:18 ` [PATCH 5/6] ARM: dts: meson8: add the DDR clock controller Martin Blumenstingl
2019-09-21 15:18 ` [PATCH 6/6] ARM: dts: meson8b: " Martin Blumenstingl
2019-09-23 10:06 ` [PATCH 0/6] add the DDR clock controller on Meson8 and Meson8b Jerome Brunet
2019-09-23 20:49   ` Martin Blumenstingl
2019-10-01 13:33     ` Jerome Brunet [this message]

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