From: Jerome Brunet <jbrunet@baylibre.com>
To: Neil Armstrong <neil.armstrong@linaro.org>
Cc: Rob Herring <robh@kernel.org>,
Krzysztof Kozlowski <krzk+dt@kernel.org>,
Conor Dooley <conor+dt@kernel.org>,
Kevin Hilman <khilman@baylibre.com>,
Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
Xianwei Zhao <xianwei.zhao@amlogic.com>,
Nick Xie <nick@khadas.com>,
devicetree@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/2] arm64: dts: amlogic: s4: assign mmc b clock to 24MHz
Date: Wed, 14 Jan 2026 11:40:59 +0100 [thread overview]
Message-ID: <1jikd4xyro.fsf@starbuckisacylon.baylibre.com> (raw)
In-Reply-To: <d55bd5c6-d5f8-45d8-9c6b-22e401f6a7ff@linaro.org> (Neil Armstrong's message of "Wed, 14 Jan 2026 10:05:35 +0100")
On mer. 14 janv. 2026 at 10:05, Neil Armstrong <neil.armstrong@linaro.org> wrote:
> On 1/14/26 09:56, Jerome Brunet wrote:
>> The amlogic MMC driver operate with the assumption that MMC clock
>> is configured to provide 24MHz. It uses this path for low
>> rates such as 400kHz.
>> This assumption did hold true until but it now, but it is apparently
>> not the case with s4. The clock has been reported to provide 1GHz
>> instead. This is most likely due to how the bootloader is using the MMC
>> clock on this platform.
>> Regardless of why the MMC clock rate is 1GHz, if the MMC driver expects
>> 24MHz, the clock should be properly assigned, so assign it.
>> Reported-by: Nick Xie <nick@khadas.com>
>> Closes: https://lore.kernel.org/linux-amlogic/20260113011931.40424-1-nick@khadas.com/
>> Fixes: 3ab9d54b5d84 ("arm64: dts: amlogic: enable some device nodes for S4")
>> Tested-by: Nick Xie <nick@khadas.com>
>> Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
>> ---
>> arch/arm64/boot/dts/amlogic/meson-s4.dtsi | 4 ++++
>> 1 file changed, 4 insertions(+)
>> diff --git a/arch/arm64/boot/dts/amlogic/meson-s4.dtsi
>> b/arch/arm64/boot/dts/amlogic/meson-s4.dtsi
>> index 9d99ed2994df..62538fd9db6b 100644
>> --- a/arch/arm64/boot/dts/amlogic/meson-s4.dtsi
>> +++ b/arch/arm64/boot/dts/amlogic/meson-s4.dtsi
>> @@ -838,6 +838,10 @@ sd: mmc@fe08a000 {
>> clock-names = "core", "clkin0", "clkin1";
>> resets = <&reset RESET_SD_EMMC_B>;
>> status = "disabled";
>> +
>> + assigned-clocks = <&clkc_periphs CLKID_SD_EMMC_B>;
>> + assigned-clock-parents = <0>;
>
> In this case, assigned-clock-parents should be dropped.
>
Dunno why I thought that was always required. I'll fix it and the other
instances
> Neil
>
>> + assigned-clock-rates = <24000000>;
>> };
>> emmc: mmc@fe08c000 {
>>
--
Jerome
_______________________________________________
linux-amlogic mailing list
linux-amlogic@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-amlogic
next prev parent reply other threads:[~2026-01-14 10:41 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-14 8:56 [PATCH v2 0/2] arm64: dts: amlogic: s4: mmc clock fixups Jerome Brunet
2026-01-14 8:56 ` [PATCH v2 1/2] arm64: dts: amlogic: s4: assign mmc b clock to 24MHz Jerome Brunet
2026-01-14 9:05 ` Neil Armstrong
2026-01-14 10:40 ` Jerome Brunet [this message]
2026-01-14 8:56 ` [PATCH v2 2/2] arm64: dts: amlogic: s4: fix mmc clock assignment Jerome Brunet
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=1jikd4xyro.fsf@starbuckisacylon.baylibre.com \
--to=jbrunet@baylibre.com \
--cc=conor+dt@kernel.org \
--cc=devicetree@vger.kernel.org \
--cc=khilman@baylibre.com \
--cc=krzk+dt@kernel.org \
--cc=linux-amlogic@lists.infradead.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=martin.blumenstingl@googlemail.com \
--cc=neil.armstrong@linaro.org \
--cc=nick@khadas.com \
--cc=robh@kernel.org \
--cc=xianwei.zhao@amlogic.com \
/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