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 09B4118E11; Sat, 28 Sep 2024 14:38:42 +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=1727534323; cv=none; b=TwvOuYdv3imtI+paK357affqSpVXP9+fXgtl80/AS5z+w0hOe6CD8PZsrq3aGtxgLFXVD8CewAJ1BOvSEmDq5EMj6a0etIzyM9/HPEHWTSBsa4KYzZD45onLRXTkKSNAgTweQh0hYjURN6ldpnpteWvwZss/O2hdf020g/A7R1o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727534323; c=relaxed/simple; bh=Mg41Czp4iLNXfN0ojsPaj+c1TJMlEK/US6inXCaque4=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=LLwQtDtXwmFupThUbtNerKBWJICv5gEqxeeMFjFTvOGtH6BbbU3tr+LFk21OLpsCpBvM+ig7y0iQ9TMWh93y8V5FOt3/WjYEb+4b/jNWQZSgHAqbwpyhxJ+VJuu8g7cVAGn1rawhNmxCPYzflRVVWORbV+4fIW6G/7Uj0YTF3Mc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Bv53OEPI; 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="Bv53OEPI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B5946C4CEC3; Sat, 28 Sep 2024 14:38:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727534322; bh=Mg41Czp4iLNXfN0ojsPaj+c1TJMlEK/US6inXCaque4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Bv53OEPI+5t7QuxkwNBcugww/BPfD+CzrZZSO3KUCbrJ99/e3agy5Dy0e21KgA09G SQgo/5X5FSy46I6Sa+o/7vtTHiW4FRFsvBtY9Uq85Gava1J2TH+oAYeykoYQSA7vXi 936KFBOtckh+uHlJ3ROYKnkgu1IZc11SYDhyh+oOlGhlLuLBB4og+QsIo1dS6SSjtd LnekcWg4xmQ1FO2GDhI2jL79zvUoRKbuhsiLuIC8O6zQxjV5l5brxTXuNot2RjUvGk bRpQBcAlxpFK7K1nySB7OxWuFmXh0RFWcc32nVXS2R0BFj2nQCwirKRWa6kUVMyUGu YGyYLZSaTvTkw== Date: Sat, 28 Sep 2024 15:38:34 +0100 From: Jonathan Cameron To: Javier Carrasco Cc: Lars-Peter Clausen , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Rishi Gupta , linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Jonathan Cameron Subject: Re: [PATCH 5/7] iio: light: veml6030: update sensor resolution Message-ID: <20240928153834.3577ef30@jic23-huawei> In-Reply-To: <5199bc7c-c3fe-49e8-9122-78b476c4aa90@gmail.com> References: <20240913-veml6035-v1-0-0b09c0c90418@gmail.com> <20240913-veml6035-v1-5-0b09c0c90418@gmail.com> <20240914155716.09496630@jic23-huawei> <5199bc7c-c3fe-49e8-9122-78b476c4aa90@gmail.com> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.43; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sun, 15 Sep 2024 10:31:11 +0200 Javier Carrasco wrote: > On 14/09/2024 16:57, Jonathan Cameron wrote: > > On Fri, 13 Sep 2024 15:19:00 +0200 > > Javier Carrasco wrote: > > > >> The driver still uses the sensor resolution provided in the datasheet > >> until Rev. 1.6, 28-Apr-2022, which was updated with Rev 1.7, > >> 28-Nov-2023. The original ambient light resolution has been updated from > >> 0.0036 lx/ct to 0.0042 lx/ct, which is the value that can be found in > >> the current device datasheet. > >> > >> Update the default resolution for IT = 100 ms and GAIN = 1/8 from the > >> original 4608 mlux/cnt to the current value from the "Resolution and > >> maximum detection range" table (Application Note 84367, page 5), 5376 > >> mlux/cnt. > >> > >> Signed-off-by: Javier Carrasco > > Interesting. So does the datasheet say this was fixing an error, or > > is there any chance there are different versions of the chip out there? > > > > Also, should we treat this as a fix? I think we probably should given > > we don't really want stable kernels to have wrong data being reported. > > If so, please reply with a fixes tag. > > > > Jonathan > > > > According to the Product Information Notification (link in the cover > letter): > > "Reason for Change: Adjusted resolution as this was wrongly stated in > the current datasheet." > > "If resolution is defined in the particular application by the customer, > no changes in the system should be made. In the case resolution was > taken from the datasheet or app note, this has to be adjusted accordingly." > > Which means that stable kernels are using the wrong resolution. I don't > know what IIO usually does in such cases, because a fix could > potentially make existing applications return "wrong data". If that is > alright, and applications are meant to be adjusted after the kernel > update, I have no problems to make this patch as a fix and add the > stable tag. It's unfortunate, but fixing a bug is a valid reason for ABI change (which this is - sort of) so existing applications will need to be fixed if anyone notices. So please send this as a fix with appropriate tags and that datasheet change log included in the patch description. Thanks, Jonathan > > Best regards, > Javier Carrasco > > >> --- > >> drivers/iio/light/veml6030.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/drivers/iio/light/veml6030.c b/drivers/iio/light/veml6030.c > >> index 5d4c2e35b987..d5add040d0b3 100644 > >> --- a/drivers/iio/light/veml6030.c > >> +++ b/drivers/iio/light/veml6030.c > >> @@ -779,7 +779,7 @@ static int veml6030_hw_init(struct iio_dev *indio_dev) > >> > >> /* Cache currently active measurement parameters */ > >> data->cur_gain = 3; > >> - data->cur_resolution = 4608; > >> + data->cur_resolution = 5376; > >> data->cur_integration_time = 3; > >> > >> return ret; > >> > > >