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Tue, 16 Jun 2026 07:03:00 -0700 (PDT) Message-ID: Date: Tue, 16 Jun 2026 16:02:58 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/2] dt-bindings: Add GPIO-locked fixed clock To: Brian Masney , V.Yurkov.EXT@bruker.com Cc: Michael Turquette , Stephen Boyd , Rob Herring , Krzysztof Kozlowski , Conor Dooley , linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org, devicetree@vger.kernel.org References: <20260603-feature-clock-guard-v3-0-01cca0aa04a5@bruker.com> <20260603-feature-clock-guard-v3-1-01cca0aa04a5@bruker.com> Content-Language: en-US From: Vyacheslav Yurkov In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Brian On 16.06.2026 00:01, Brian Masney wrote: > Hi Vyacheslav, > > On Wed, Jun 03, 2026 at 11:16:42AM +0000, Vyacheslav Yurkov via B4 Relay wrote: >> From: Vyacheslav Yurkov >> >> Some hardware designs provide fixed-frequency clocks generated outside >> software control, such as by FPGA-resident PLLs. While the clock rate is >> fixed, a separate GPIO signal indicates whether the clock source is >> locked and producing a valid output. >> >> Describe a GPIO-locked fixed clock provider that exposes a fixed-rate >> clock whose availability depends on one or more GPIO lock-status >> signals. >> >> Signed-off-by: Vyacheslav Yurkov >> Signed-off-by: Vyacheslav Yurkov >> --- >> .../bindings/clock/gpio-locked-fixed-clock.yaml | 70 ++++++++++++++++++++++ >> 1 file changed, 70 insertions(+) >> >> diff --git a/Documentation/devicetree/bindings/clock/gpio-locked-fixed-clock.yaml b/Documentation/devicetree/bindings/clock/gpio-locked-fixed-clock.yaml >> new file mode 100644 >> index 000000000000..9106b800b673 >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/clock/gpio-locked-fixed-clock.yaml >> @@ -0,0 +1,70 @@ >> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) >> +%YAML 1.2 >> +--- >> +$id: http://devicetree.org/schemas/clock/gpio-locked-fixed-clock.yaml# >> +$schema: http://devicetree.org/meta-schemas/core.yaml# >> + >> +title: GPIO Locked Fixed Clock >> + >> +maintainers: >> + - Vyacheslav Yurkov >> + >> +description: | >> + Provides a clock output whose availability depends on a set of >> + prerequisite conditions. These conditions include the presence of >> + one or more parent clocks and the asserted state of one or more >> + GPIO lock indicators. An example of such clocks is FPGA clock that >> + are outside CPU control, with the lock status exposed through GPIO >> + signal. >> + >> + The output clock is considered available only when all configured >> + prerequisites are satisfied. > > I'm stepping outside my usual review of just the clk drivers. Krzysztof > in v1 and v2 asked for more detailed hardware explanation. This feels to > me like this is a policy that says to not use these clocks until the > GPIO says they are ready. My gut feeling is that details like this > should live in a clk driver instead of a dt-binding. > > Alternatively, if this is generic enough, then could > Documentation/devicetree/bindings/clock/gated-fixed-clock.yaml be > extended? > > Brian Does it mean I should drop driver description from the DT schema? So you are implying that gated-fixed-clock.yaml can be extended with another compatibility string? When another compatibility string is used, then some other bindings are expected by the driver, not what is used by gated-fixed-clock driver. Is that a common pattern among dt-bindings to share the bindings between different compatibility strings? Slava