From: qianfan <qianfanguijin@163.com>
To: Maxime Ripard <maxime@cerno.tech>
Cc: linux-sunxi@lists.linux.dev, Rob Herring <robh+dt@kernel.org>,
Chen-Yu Tsai <wens@csie.org>,
Jernej Skrabec <jernej.skrabec@gmail.com>,
"Rafael J . Wysocki" <rafael@kernel.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Subject: Re: [PATCH v3 2/2] ARM: dts: sun8i-r40: Add "cpu-supply" node for sun8i-r40 based board
Date: Fri, 13 May 2022 16:23:20 +0800 [thread overview]
Message-ID: <666ead08-af1e-81f5-6fe1-e5e3370e6d6f@163.com> (raw)
In-Reply-To: <20220513081556.knd3tf6pangfblh3@houat>
在 2022/5/13 16:15, Maxime Ripard 写道:
> On Fri, May 13, 2022 at 03:48:50PM +0800, qianfan wrote:
>>
>> 在 2022/5/13 15:38, Maxime Ripard 写道:
>>> Hi,
>>>
>>> On Thu, May 12, 2022 at 03:18:58PM +0800, qianfanguijin@163.com wrote:
>>>> From: qianfan Zhao <qianfanguijin@163.com>
>>>>
>>>> sun8i-r40 actived cpufreq feature now, let's add "cpu-supply" node on
>>>> board.
>>>>
>>>> Signed-off-by: qianfan Zhao <qianfanguijin@163.com>
>>>> ---
>>>> arch/arm/boot/dts/sun8i-r40-bananapi-m2-ultra.dts | 4 ++++
>>>> arch/arm/boot/dts/sun8i-r40-feta40i.dtsi | 4 ++++
>>>> arch/arm/boot/dts/sun8i-t3-cqa3t-bv3.dts | 4 ++++
>>>> arch/arm/boot/dts/sun8i-v40-bananapi-m2-berry.dts | 4 ++++
>>>> 4 files changed, 16 insertions(+)
>>>>
>>>> diff --git a/arch/arm/boot/dts/sun8i-r40-bananapi-m2-ultra.dts b/arch/arm/boot/dts/sun8i-r40-bananapi-m2-ultra.dts
>>>> index a6a1087a0c9b..4f30018ec4a2 100644
>>>> --- a/arch/arm/boot/dts/sun8i-r40-bananapi-m2-ultra.dts
>>>> +++ b/arch/arm/boot/dts/sun8i-r40-bananapi-m2-ultra.dts
>>>> @@ -113,6 +113,10 @@ &ahci {
>>>> status = "okay";
>>>> };
>>>> +&cpu0 {
>>>> + cpu-supply = <®_dcdc2>;
>>>> +};
>>>> +
>>> This will break bisection on those boards. Indeed, you added the OPPs on
>>> the first patch, and if you only apply that patch, the boards in the
>>> second patch will be missing their CPU regulator. The kernel will then
>>> ramp up the frequency to the highest OPP, but will not change the
>>> voltage, resulting in a crash.
>> This is a good point and I will merge those two patch.
> That's not what I meant to say. Those two patches are great separated.
> You can invert them though.
haha, invert them, so interesting. good idea.
>
>>> There's a similar issue for all the boards that don't have a regulator
>>> in the first place.
>>>
>>> The way we worked around this for the other SoCs is to have a DTSI with
>>> the OPPs with a frequency higher than what U-Boot boots with (1008MHz?),
>>> and only include that DTSI on boards that have a CPU regulator hooked in.
>> Is this really necessary? It seems like every board based on sun8i-r40
>> have a cpu regulator.
> This probably won't be the case whenever someone starts a new design,
> and then they'll face random crashes for no apparent reason, and waste a
> lot of time in the process.
>
> Whereas the alternative is that you would be missing some OPPs,
> something that is fairly easy to figure out.
How about remove the OPPs which greate that 1.08G in sun8i-r40.dtsi,
If some boards want to run at a higher frequency, can add them byself
in the board's file.
>
> Maxime
next prev parent reply other threads:[~2022-05-13 8:24 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-12 7:18 [PATCH v3 1/2] ARM: dts: sun8i-r40: add opp table for cpu qianfanguijin
2022-05-12 7:18 ` [PATCH v3 2/2] ARM: dts: sun8i-r40: Add "cpu-supply" node for sun8i-r40 based board qianfanguijin
2022-05-13 7:38 ` Maxime Ripard
2022-05-13 7:48 ` qianfan
2022-05-13 8:15 ` Maxime Ripard
2022-05-13 8:23 ` qianfan [this message]
2022-05-16 7:53 ` Maxime Ripard
2022-05-16 15:39 ` Chen-Yu Tsai
2022-05-12 7:29 ` [PATCH v3 1/2] ARM: dts: sun8i-r40: add opp table for cpu Viresh Kumar
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=666ead08-af1e-81f5-6fe1-e5e3370e6d6f@163.com \
--to=qianfanguijin@163.com \
--cc=devicetree@vger.kernel.org \
--cc=jernej.skrabec@gmail.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=linux-sunxi@lists.linux.dev \
--cc=maxime@cerno.tech \
--cc=rafael@kernel.org \
--cc=robh+dt@kernel.org \
--cc=viresh.kumar@linaro.org \
--cc=wens@csie.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).