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 0A0E1254B00; Tue, 4 Mar 2025 16:39:39 +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=1741106380; cv=none; b=VXuY3oXGokjF4uuF+ZY4WIok7MCo3ncfBF7DrM8DY4yveKDJLCgsOUP6pvlOajfV6evhCaN5D5mcOSkh2smNd+ncKvIEEuaN/ONZyoVvEDImxg0t/SZ8Qn19TFXzaPwgxCAFWCdh9GmpwJigID6NXDa96VKife5UDa/vuY2MmWQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741106380; c=relaxed/simple; bh=GtZvw6f8Z5eNW+3bcxw3YYu0cJDMrovxZ+BIEA+TAeQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=nZj+9msAneLFnxsmF1fp7865VaUw1Y5Hnq/greH4BSCq/t7RUQRgG9JrskaYRNL+qXryZSslTDf9Y/TRKgvRWSnXQaJg4CXQQqn6ZApejEHSS5VTkrYZdTR4+6eG6jnNTKWJ3ub5GrE7kI90F4qNDTb3n0/899K82/qa7te1dXY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sqCDFYQe; 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="sqCDFYQe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 35771C4CEE9; Tue, 4 Mar 2025 16:39:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1741106379; bh=GtZvw6f8Z5eNW+3bcxw3YYu0cJDMrovxZ+BIEA+TAeQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=sqCDFYQe49SBsHlcGbi00NuputI544lsbO/cMWWB6pMtkLnl2yCpuxhHM5YHgHPiR Fd3FZB/GfnJ+WP5iECGlIX9iGwp6nHt3R58d+18WCgAgoDLKjyg9WGm4OjCKBrJS0c nSpSCIrtli8m1MIdTPM35gHnHS99qE8ttwxYaEP5R8Gv4hVp0ezoZoisV5WCBzWCUm a6EZRo+p1GF++/SNU9SXYOVBAaSZ13GeKLl1XS/exRBA6r0fJ2Q0j8dhl9rG/eiePU 62SfJOkdTNN+Hk6DmundTzG1qPE0SRxVuljXM66XQVehOcb3Kmh6Uj7pV6zjQapG0c P3Wx7mXUs9hRw== Date: Tue, 4 Mar 2025 16:39:34 +0000 From: Conor Dooley To: Mathis Foerst Cc: Sakari Ailus , linux-kernel@vger.kernel.org, Laurent Pinchart , MauroCarvalhoChehab@mt.com, mchehab@kernel.org, Rob Herring , Krzysztof Kozlowski , Conor Dooley , linux-media@vger.kernel.org, devicetree@vger.kernel.org, manuel.traut@mt.com Subject: Re: [PATCH v1 2/8] MT9M114: Add pad-slew-rate DT-binding Message-ID: <20250304-expend-isotope-cea613f4e9d5@spud> References: <20250226153929.274562-1-mathis.foerst@mt.com> <20250226153929.274562-3-mathis.foerst@mt.com> <20250228-helpless-delivery-42162772caa3@spud> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="dQ9D5BXcovtjIkOJ" Content-Disposition: inline In-Reply-To: --dQ9D5BXcovtjIkOJ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Mar 04, 2025 at 12:48:58PM +0100, Mathis Foerst wrote: > Hi Conor, Hi Sakari, >=20 > On Fri, Feb 28, 2025 at 07:11:31PM +0000, Conor Dooley wrote: > > On Thu, Feb 27, 2025 at 10:14:02AM +0000, Sakari Ailus wrote: > > > Hi Mathis, > > >=20 > > > On Wed, Feb 26, 2025 at 04:39:23PM +0100, Mathis Foerst wrote: > > > > The MT9M114 supports the different slew rates (0 to 7) on the outpu= t pads. > > >=20 > > > "the output pads" probably means pixel data interface (DVP or CSI-2) > > > signals in this cases? I suppose this is about clock modulation? > > > It'd be good to say that. >=20 > The slew rate defines the slope of the voltage flanks on the output pads = (how fast > the pads go from LOW to HIGH or vice versa). I tried to clarify the descr= iption. >=20 > > >=20 > > > > At the moment, this is hardcoded to 7 (the fastest rate). > > > > The user might want to change this values due to EMC requirements. > > > >=20 > > > > Add the 'pad-slew-rate' property to the MT9M114 DT-bindings for sel= ecting > > > > the desired slew rate. > > > >=20 > > > > Signed-off-by: Mathis Foerst > > > > --- > > > > .../devicetree/bindings/media/i2c/onnn,mt9m114.yaml | 6 ++= ++++ > > > > 1 file changed, 6 insertions(+) > > > >=20 > > > > diff --git a/Documentation/devicetree/bindings/media/i2c/onnn,mt9m1= 14.yaml b/Documentation/devicetree/bindings/media/i2c/onnn,mt9m114.yaml > > > > index 72e258d57186..666afe10c538 100644 > > > > --- a/Documentation/devicetree/bindings/media/i2c/onnn,mt9m114.yaml > > > > +++ b/Documentation/devicetree/bindings/media/i2c/onnn,mt9m114.yaml > > > > @@ -74,6 +74,12 @@ properties: > > > > description: Bypass the internal PLL of the sensor to use EXTC= LK directly as SYSCLK. > > > > type: boolean > > > > =20 > > > > + onnn,slew-rate: > > > > + $ref: /schemas/types.yaml#/definitions/uint8 > > >=20 > > > No need to make this 8-bit (i.e. just use 32 bits). >=20 > Okay, I thought 8-bit would fit the small value range [0,7]. Changed it t= o 32 bits. >=20 > > >=20 > > > > + description: Slew rate ot the output pads DOUT[7:0], LINE_VALI= D, FRAME_VALID and PIXCLK > > >=20 > > > Please wrap at 80 characters. > > >=20 > > > Is there more information on the effect than 7 is the fastest? >=20 > There is no more information about the exact meaning of the values. > As described above, the higher the value, the steeper the voltage flanks. >=20 > > >=20 > > > > + minimum: 0 > > > > + maximum: 7 > > >=20 > > > Please also add a default. >=20 > Sure, I added the default value 7 that matches the currently hardcoded=20 > value in the driver. >=20 > >=20 > > It'd also be great (IMO) if it were given in terms of actual units, not > > nebulous values that I assume to be the register values. >=20 > I agree, but the documentation does not provide further details about the > unit of the value. So using the register value is my best-effort approach. If they don't provide em, how is anyone meant to calculate what's correct? Trial and error? --dQ9D5BXcovtjIkOJ Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCZ8csxgAKCRB4tDGHoIJi 0mBdAQCh0+RwNviWTSOdkFgmzH6AVYCtzFNH8Vy/YBQEPCEirQEAo8Wp+QCf9P5F XB0issuH+ym8sZdYbvhaKMOzJw3GpgU= =vHbn -----END PGP SIGNATURE----- --dQ9D5BXcovtjIkOJ--