From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
To: Douglas Anderson <dianders@chromium.org>,
Bjorn Andersson <andersson@kernel.org>,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Mark Brown <broonie@kernel.org>,
Linus Walleij <linus.walleij@linaro.org>
Cc: Matthias Kaehlcke <mka@chromium.org>,
Konrad Dybcio <konrad.dybcio@linaro.org>,
linux-gpio@vger.kernel.org, Stephen Boyd <swboyd@chromium.org>,
devicetree@vger.kernel.org, linux-arm-msm@vger.kernel.org,
linux-spi@vger.kernel.org, Andy Gross <agross@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 07/14] dt-bindings: pinctrl: qcom: Add output-enable
Date: Mon, 27 Mar 2023 09:22:45 +0200 [thread overview]
Message-ID: <510cf7ac-3f7f-49e2-b384-424c931b2750@linaro.org> (raw)
In-Reply-To: <20230323102605.7.I7874c00092115c45377c2a06f7f133356956686e@changeid>
On 23/03/2023 18:30, Douglas Anderson wrote:
> In the patch ("dt-bindings: pinctrl: qcom: tlmm should use
> output-disable, not input-enable") we allowed setting "output-disable"
> for TLMM pinctrl states. Let's also add "output-enable".
>
> At first blush this seems a needless thing to do. Specifically:
> - In Linux (and presumably any other OSes using the same device trees)
> the GPIO/pinctrl driver knows to automatically enable the output
> when a GPIO is changed to an output. Thus in most cases specifying
> "output-enable" is superfluous and should be avoided.
> - If we need to set a pin's default state we already have
> "output-high" and "output-low" and these properties already imply
> "output-enabled" (at least on the Linux Qualcomm TLMM driver).
>
> However, there is one instance where "output-enable" seems like it
> could be useful: sleep states. It's not uncommon to want to configure
> pins as inputs (with appropriate pulls) when the driver controlling
> them is in a low power state. Then we want the pins back to outputs
> when the driver wants things running normally. To accomplish this we'd
> want to be able to use "output-enable". Then the "default" state could
> have "output-enable" and the "sleep" state could have
> "output-disable".
>
> NOTE: in all instances I'm aware of, we'd only want to use
> "output-enable" on pins that are configured as "gpio". The Qualcomm
> documentation that I have access to says that "output-enable" only
> does something useful when in GPIO mode.
>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Best regards,
Krzysztof
next prev parent reply other threads:[~2023-03-27 7:22 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-23 17:30 [PATCH 00/14] Control Quad SPI pinctrl better on Qualcomm Chromebooks Douglas Anderson
2023-03-23 17:30 ` [PATCH 01/14] arm64: dts: sc7180: Rename qspi data12 as data23 Douglas Anderson
2023-03-23 17:30 ` [PATCH 02/14] arm64: dts: sc7280: " Douglas Anderson
2023-03-23 17:30 ` [PATCH 03/14] arm64: dts: sdm845: " Douglas Anderson
2023-03-23 17:30 ` [PATCH 04/14] arm64: dts: qcom: sc7180: Annotate l13a on trogdor to always-on Douglas Anderson
2023-03-23 17:30 ` [PATCH 05/14] spi: spi-qcom-qspi: Support pinctrl sleep states Douglas Anderson
2023-03-23 17:30 ` [PATCH 06/14] dt-bindings: pinctrl: qcom: tlmm should use output-disable, not input-enable Douglas Anderson
2023-03-27 7:21 ` Krzysztof Kozlowski
2023-03-23 17:30 ` [PATCH 07/14] dt-bindings: pinctrl: qcom: Add output-enable Douglas Anderson
2023-03-27 7:22 ` Krzysztof Kozlowski [this message]
2023-03-23 17:30 ` [PATCH 08/14] pinctrl: qcom: Support OUTPUT_ENABLE; deprecate INPUT_ENABLE Douglas Anderson
2023-03-24 13:55 ` Bjorn Andersson
2023-03-23 17:30 ` [PATCH 09/14] arm64: dts: qcom: sc7180: Remove superfluous "input-enable"s from trogdor Douglas Anderson
2023-03-23 17:30 ` [PATCH 10/14] arm64: dts: qcom: sc7280: Remove superfluous "input-enable"s from idp-ec-h1 Douglas Anderson
2023-03-23 17:30 ` [PATCH 11/14] arm64: dts: qcom: sdm845: Remove superfluous "input-enable"s from cheza Douglas Anderson
2023-03-23 17:30 ` [PATCH 12/14] arm64: dts: qcom: sc7180: Fix trogdor qspi pin config Douglas Anderson
2023-04-07 18:11 ` Krzysztof Kozlowski
2023-04-07 19:53 ` Doug Anderson
2023-04-08 10:52 ` Krzysztof Kozlowski
2023-03-23 17:30 ` [PATCH 13/14] arm64: dts: qcom: sc7280: Fix " Douglas Anderson
2023-03-23 17:30 ` [PATCH 14/14] arm64: dts: qcom: sdm845: Fix cheza " Douglas Anderson
2023-03-27 21:44 ` [PATCH 00/14] Control Quad SPI pinctrl better on Qualcomm Chromebooks Linus Walleij
2023-03-27 21:51 ` Doug Anderson
2023-03-29 8:50 ` Linus Walleij
2023-04-07 17:55 ` Bjorn Andersson
2023-03-28 13:06 ` (subset) " Mark Brown
2023-04-07 18:00 ` Bjorn Andersson
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