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([2a01:e0a:106d:1080:1029:e3c5:362e:1250]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48fe4dac000sm265809055e9.0.2026.05.18.07.32.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 May 2026 07:32:01 -0700 (PDT) Message-ID: <72b341e6-5ada-48e9-a9c1-a442810b15da@linaro.org> Date: Mon, 18 May 2026 16:32:00 +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 From: Neil Armstrong Reply-To: Neil Armstrong Subject: Re: [PATCH] pinctrl: meson: amlogic-a4: fix gpio output glitch To: xianwei.zhao@amlogic.com, Linus Walleij , Kevin Hilman , Jerome Brunet , Martin Blumenstingl Cc: linux-amlogic@lists.infradead.org, linux-gpio@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20260518-fix-set-value-glitch-v1-1-d350732dc934@amlogic.com> Content-Language: en-US, fr Autocrypt: addr=neil.armstrong@linaro.org; keydata= xsBNBE1ZBs8BCAD78xVLsXPwV/2qQx2FaO/7mhWL0Qodw8UcQJnkrWmgTFRobtTWxuRx8WWP GTjuhvbleoQ5Cxjr+v+1ARGCH46MxFP5DwauzPekwJUD5QKZlaw/bURTLmS2id5wWi3lqVH4 BVF2WzvGyyeV1o4RTCYDnZ9VLLylJ9bneEaIs/7cjCEbipGGFlfIML3sfqnIvMAxIMZrvcl9 qPV2k+KQ7q+aXavU5W+yLNn7QtXUB530Zlk/d2ETgzQ5FLYYnUDAaRl+8JUTjc0CNOTpCeik 80TZcE6f8M76Xa6yU8VcNko94Ck7iB4vj70q76P/J7kt98hklrr85/3NU3oti3nrIHmHABEB AAHNKk5laWwgQXJtc3Ryb25nIDxuZWlsLmFybXN0cm9uZ0BsaW5hcm8ub3JnPsLAkQQTAQoA OwIbIwULCQgHAwUVCgkICwUWAgMBAAIeAQIXgBYhBInsPQWERiF0UPIoSBaat7Gkz/iuBQJk Q5wSAhkBAAoJEBaat7Gkz/iuyhMIANiD94qDtUTJRfEW6GwXmtKWwl/mvqQtaTtZID2dos04 YqBbshiJbejgVJjy+HODcNUIKBB3PSLaln4ltdsV73SBcwUNdzebfKspAQunCM22Mn6FBIxQ GizsMLcP/0FX4en9NaKGfK6ZdKK6kN1GR9YffMJd2P08EO8mHowmSRe/ExAODhAs9W7XXExw UNCY4pVJyRPpEhv373vvff60bHxc1k/FF9WaPscMt7hlkbFLUs85kHtQAmr8pV5Hy9ezsSRa GzJmiVclkPc2BY592IGBXRDQ38urXeM4nfhhvqA50b/nAEXc6FzqgXqDkEIwR66/Gbp0t3+r yQzpKRyQif3OwE0ETVkGzwEIALyKDN/OGURaHBVzwjgYq+ZtifvekdrSNl8TIDH8g1xicBYp QTbPn6bbSZbdvfeQPNCcD4/EhXZuhQXMcoJsQQQnO4vwVULmPGgtGf8PVc7dxKOeta+qUh6+ SRh3vIcAUFHDT3f/Zdspz+e2E0hPV2hiSvICLk11qO6cyJE13zeNFoeY3ggrKY+IzbFomIZY 4yG6xI99NIPEVE9lNBXBKIlewIyVlkOaYvJWSV+p5gdJXOvScNN1epm5YHmf9aE2ZjnqZGoM Mtsyw18YoX9BqMFInxqYQQ3j/HpVgTSvmo5ea5qQDDUaCsaTf8UeDcwYOtgI8iL4oHcsGtUX oUk33HEAEQEAAcLAXwQYAQIACQUCTVkGzwIbDAAKCRAWmrexpM/4rrXiB/sGbkQ6itMrAIfn M7IbRuiSZS1unlySUVYu3SD6YBYnNi3G5EpbwfBNuT3H8//rVvtOFK4OD8cRYkxXRQmTvqa3 3eDIHu/zr1HMKErm+2SD6PO9umRef8V82o2oaCLvf4WeIssFjwB0b6a12opuRP7yo3E3gTCS KmbUuLv1CtxKQF+fUV1cVaTPMyT25Od+RC1K+iOR0F54oUJvJeq7fUzbn/KdlhA8XPGzwGRy 4zcsPWvwnXgfe5tk680fEKZVwOZKIEuJC3v+/yZpQzDvGYJvbyix0lHnrCzq43WefRHI5XTT QbM0WUIBIcGmq38+OgUsMYu4NzLu7uZFAcmp6h8g Organization: Linaro In-Reply-To: <20260518-fix-set-value-glitch-v1-1-d350732dc934@amlogic.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 5/18/26 10:26, Xianwei Zhao via B4 Relay wrote: > From: Xianwei Zhao > > When the system transitions from bootloader to kernel, the GPIO is > expected to keep driving high. > > However, the Linux kernel first configures the pin direction and then > sets the output value. This may cause a brief low-level glitch on the > GPIO line, which can be problematic for regulator control. > > By configuring the output value before switching the pin direction to > output, the glitch can be avoided. > > This commit fixes the issue by swapping the configuration order. > > Fixes: 6e9be3abb78c ("pinctrl: Add driver support for Amlogic SoCs") > Signed-off-by: Xianwei Zhao > --- > fix one issue when set gpio line high. > --- > drivers/pinctrl/meson/pinctrl-amlogic-a4.c | 15 +++++++-------- > 1 file changed, 7 insertions(+), 8 deletions(-) > > diff --git a/drivers/pinctrl/meson/pinctrl-amlogic-a4.c b/drivers/pinctrl/meson/pinctrl-amlogic-a4.c > index 35d27626a336..1bd58fbbd26a 100644 > --- a/drivers/pinctrl/meson/pinctrl-amlogic-a4.c > +++ b/drivers/pinctrl/meson/pinctrl-amlogic-a4.c > @@ -548,11 +548,11 @@ static int aml_pinconf_set_output_drive(struct aml_pinctrl *info, > { > int ret; > > - ret = aml_pinconf_set_output(info, pin, true); > + ret = aml_pinconf_set_drive(info, pin, high); > if (ret) > return ret; > > - return aml_pinconf_set_drive(info, pin, high); > + return aml_pinconf_set_output(info, pin, true); > } > > static int aml_pinconf_set(struct pinctrl_dev *pcdev, unsigned int pin, > @@ -921,15 +921,14 @@ static int aml_gpio_direction_output(struct gpio_chip *chip, unsigned int gpio, > unsigned int bit, reg; > int ret; > > - aml_gpio_calc_reg_and_bit(bank, AML_REG_DIR, gpio, ®, &bit); > - ret = regmap_update_bits(bank->reg_gpio, reg, BIT(bit), 0); > + aml_gpio_calc_reg_and_bit(bank, AML_REG_OUT, gpio, ®, &bit); > + ret = regmap_update_bits(bank->reg_gpio, reg, BIT(bit), > + value ? BIT(bit) : 0); > if (ret < 0) > return ret; > > - aml_gpio_calc_reg_and_bit(bank, AML_REG_OUT, gpio, ®, &bit); > - > - return regmap_update_bits(bank->reg_gpio, reg, BIT(bit), > - value ? BIT(bit) : 0); > + aml_gpio_calc_reg_and_bit(bank, AML_REG_DIR, gpio, ®, &bit); > + return regmap_update_bits(bank->reg_gpio, reg, BIT(bit), 0); > } > > static int aml_gpio_set(struct gpio_chip *chip, unsigned int gpio, int value) > > --- > base-commit: 73d4991a6949eedb51e442d4e81415017d85975b > change-id: 20260518-fix-set-value-glitch-f43cd366c295 > > Best regards, Reviewed-by: Neil Armstrong Thanks, Neil