From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9856D4594A; Tue, 30 Dec 2025 13:49:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767102577; cv=none; b=dceSpLFcPzIMSvbUMBEswk1GgroohDhQ53GZOWiPVjTLaPC+dfOANDjG3aBThwys+MgKcPI0HJ16GO3MvSg7ufSN+QSd9F2o9jxZMMEqxOq3gg/h79soUVnec9wb0P5Nuh06EgEl0vJlCTBSaRoeDLVShG6Hgl8jBPtwZj9us6s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767102577; c=relaxed/simple; bh=BMKckrcJbKgUB3ATuX/quQBrW8laOEYXTE5aHAQjjEY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=YpR4AHY6jA3uWy5VerUlDsiXI5ng/UUbGkHwPPcWAnJqyWZZFzm0aq7ipd/P5FP9jIeybZPauj6HlPriR1CMphRQOCOUJjY9bt4PSau8MBU/CATycrPUOGYG0IiV7Lu5xYLXXxR9r/ugEjhHHYeAxLSh+udayxqedO768eEL/1E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FYnlxltm; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="FYnlxltm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 69B60C4CEFB; Tue, 30 Dec 2025 13:49:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767102577; bh=BMKckrcJbKgUB3ATuX/quQBrW8laOEYXTE5aHAQjjEY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=FYnlxltmcpkwxi34H9EuwqNkHpjYwFVroTW9HN2CHYF4AorIOWwuuQijkYDRph0Fn nFDIz24rrrdFdI0Ygb0iDOekJVoxzRMr7+zYcAo0XJfSObdauZPNLJ/TyLa5z+djh2 sGd5g8T1oPhaAsiCjI/1A1E9aQ8fCOSkScXfClnA2LtWhijDnbtrvmVohv/bm4a/KQ +a7WFhWPXELeCOvGuN6RLuGR0COcdnj8MxDKA9rmlYVsT+jKpbwcLG7XYHkV96Y1RA jBsTOkIGvHTJ3VfN3ja2bI/ulskTCH/jzmjdMmPAQcMF4ysByRrEyD7EBQWcbZAVPe rM/4Zthdg1WUg== Message-ID: <954ecfcb-3d5f-4b65-9d59-4a5bdb067803@kernel.org> Date: Tue, 30 Dec 2025 14:49:32 +0100 Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/4] media: i2c: ov9282: Fix reset-gpio logical state To: Loic Poulain , Sakari Ailus Cc: andersson@kernel.org, konradybcio@kernel.org, dave.stevenson@raspberrypi.com, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, mchehab@kernel.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-media@vger.kernel.org, laurent.pinchart@ideasonboard.com References: <20251114133822.434171-1-loic.poulain@oss.qualcomm.com> <20251114133822.434171-2-loic.poulain@oss.qualcomm.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 03/12/2025 11:00, Loic Poulain wrote: > Hi Laurent, > > On Mon, Nov 17, 2025 at 6:30 PM Sakari Ailus > wrote: >> >> Hi Loic, >> >> On Fri, Nov 14, 2025 at 02:38:19PM +0100, Loic Poulain wrote: >>> Ensure reset state is low in the power-on state and high in the >>> power-off state (assert reset). Note that the polarity is abstracted >>> by the GPIO subsystem, so the logic level reflects the intended reset >>> behavior. >> >> That's an interesting approach to fix DTS gone systematically wrong. >> >> I was thinking of the drivers that have this issue, too, but I would have >> introduced a new GPIO under a different name (many sensors use "enable", >> too). Any thoughts? >> >> Cc Laurent. > > Do you have any feedback on this change? > >> >>> >>> To maintain backward compatibility with DTS files that use an incorrect >>> flag, we implement a mechanism similar to: >>> commit 738455858a2d ("ASoC: codecs: wsa881x: Use proper shutdown GPIO polarity") >>> >>> Signed-off-by: Loic Poulain >>> --- >>> drivers/media/i2c/ov9282.c | 26 ++++++++++++++++++++++---- >>> 1 file changed, 22 insertions(+), 4 deletions(-) >>> >>> diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c >>> index a9f6176e9729..e79b326cdd94 100644 >>> --- a/drivers/media/i2c/ov9282.c >>> +++ b/drivers/media/i2c/ov9282.c >>> @@ -160,6 +160,7 @@ struct ov9282_mode { >>> * @sd: V4L2 sub-device >>> * @pad: Media pad. Only one pad supported >>> * @reset_gpio: Sensor reset gpio >>> + * @reset_gpio_val: Logical value to reset the sensor >>> * @inclk: Sensor input clock >>> * @supplies: Regulator supplies for the sensor >>> * @ctrl_handler: V4L2 control handler >>> @@ -180,6 +181,7 @@ struct ov9282 { >>> struct v4l2_subdev sd; >>> struct media_pad pad; >>> struct gpio_desc *reset_gpio; >>> + unsigned int reset_gpio_val; >>> struct clk *inclk; >>> struct regulator_bulk_data supplies[OV9282_NUM_SUPPLIES]; >>> struct v4l2_ctrl_handler ctrl_handler; >>> @@ -1127,13 +1129,29 @@ static int ov9282_parse_hw_config(struct ov9282 *ov9282) >>> >>> /* Request optional reset pin */ >>> ov9282->reset_gpio = devm_gpiod_get_optional(ov9282->dev, "reset", >>> - GPIOD_OUT_LOW); >>> + GPIOD_OUT_HIGH); >>> if (IS_ERR(ov9282->reset_gpio)) { >>> dev_err(ov9282->dev, "failed to get reset gpio %ld", >>> PTR_ERR(ov9282->reset_gpio)); >>> return PTR_ERR(ov9282->reset_gpio); >>> } >>> >>> + /* >>> + * Backwards compatibility work-around. >>> + * >>> + * The reset GPIO is active-low, but the driver has always used the >>> + * gpiod API with inverted logic. As a result, the DTS had to >>> + * incorrectly mark the GPIO as active-high to compensate for this >>> + * behavior. Changing the flag in the driver now would break backward >>> + * compatibility with existing DTS configurations. To address this, >>> + * we add a simple value inversion so the driver works with both old >>> + * and new DTS. This obviously is not true - driver will fail to work with some of old DTS. I am surprised that it is second approach last weeks duplicating the same problem and claiming the same - the change is backwards compatible, while it is not - instead of taking my old explanation from WSA drivers and admit the actual case of broken DTS. With proper description I could agree, but with incorrect claims - no, it's wrong. Best regards, Krzysztof