From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (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 268192459C5; Mon, 27 Oct 2025 01:19:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761527985; cv=none; b=Ty2/PCT4qtzHc+npmyjuL+mvF7cA/28L72389I0UHNMIyoFlc7hjatIOekF5rfGQ+s9lcgtDmt3HvZPlNvW1zmn6cW5MhltWicqsJ+TkLyPR2Qc2j4fEkre00J4lAtoAoWGRf59bxarg65IkmyYVA6+hCLGvR0ya+UwACn3CSt4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761527985; c=relaxed/simple; bh=FS+KlOZTayfUweHo35RYfizlXiiTS/dCMqOAye4j6/s=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=SJGPq10OVDgKqpc+hSiarMZn1QFFdfe8tot/58wSCenIcl109MdccldGbr0SlYelsd06EMPlomFBNkMG/dHy1qXDzHSV3EsyD/bYp/CUvh+esW8MIkv41bGcEKyGsgN82cx1MCDxWxi0qcY7CfLZXie/wj2h8n3QuWla1Mn/amc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=cSr4M6GX; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="cSr4M6GX" Received: from pendragon.ideasonboard.com (82-203-161-16.bb.dnainternet.fi [82.203.161.16]) by perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id 8594D14A6; Mon, 27 Oct 2025 02:17:53 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1761527873; bh=FS+KlOZTayfUweHo35RYfizlXiiTS/dCMqOAye4j6/s=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cSr4M6GXYmVqXJ9DNbAIsvskO1G8IzD4w5TqPONHF5q/NBWj+wASYuTLdhVHb38C2 7YKeykbbg0p9Y3WWXgQjfVYQejOJXz1HsTyGjxy1DTjXtadyc/uwMysXRqBDDPCp/p 1q1pdqj5EsuYsjtJ1H0vlJ1rVgpwGLaEfTbbQTHY= Date: Mon, 27 Oct 2025 03:19:27 +0200 From: Laurent Pinchart To: Frank Li Cc: Rui Miguel Silva , Martin Kepplinger , Purism Kernel Team , Mauro Carvalho Chehab , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Eugen Hristev , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Peng Fan , Alice Yuan , Vinod Koul , Kishon Vijay Abraham I , Philipp Zabel , Steve Longerbeam , Greg Kroah-Hartman , linux-media@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-phy@lists.infradead.org, linux-staging@lists.linux.dev Subject: Re: [PATCH v3 02/31] media: v4l2-common: Add helper function v4l_get_required_align_by_bpp() Message-ID: <20251027011927.GS13023@pendragon.ideasonboard.com> References: <20250821-95_cam-v3-0-c9286fbb34b9@nxp.com> <20250821-95_cam-v3-2-c9286fbb34b9@nxp.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20250821-95_cam-v3-2-c9286fbb34b9@nxp.com> On Thu, Aug 21, 2025 at 04:15:37PM -0400, Frank Li wrote: > Add helper v4l_get_required_align_by_bpp() to help get width alignment > requirement. Basic replace below logic and enhance to any 2^[0..31] in > drivers/media/platform/nxp/imx-mipi-csis.c > > mipi_csis_set_fmt( > { > ... > > switch (csis_fmt->width % 8) { > case 0: > align = 0; > break; > case 4: > align = 1; > break; > case 2: > case 6: > align = 2; > break; > default: > /* 1, 3, 5, 7 */ > align = 3; > break; > } > ... > } > > Signed-off-by: Frank Li > --- > The same patch will be see at https://lore.kernel.org/imx/20250729-imx8qxp_pcam-v4-2-4dfca4ed2f87@nxp.com/ > dw csi2 patch also this > --- > include/media/v4l2-common.h | 30 ++++++++++++++++++++++++++++++ > 1 file changed, 30 insertions(+) > > diff --git a/include/media/v4l2-common.h b/include/media/v4l2-common.h > index 39dd0c78d70f7b935c2e10f9767646d2cedd3079..0a9da5e8daaddf26903d9ff4bed08b283dcd38b2 100644 > --- a/include/media/v4l2-common.h > +++ b/include/media/v4l2-common.h > @@ -704,4 +704,34 @@ static inline bool v4l2_is_quant_valid(__u8 quantization) > quantization == V4L2_QUANTIZATION_LIM_RANGE; > } > > +/** > + * v4l_get_required_align_by_bpp - get align requirement for > + * v4l_bound_align_image(). (bpp * width) % (1 << align) have to be 0. > + * given number bpp, get width's alignment requirement. For example, > + * if align is 3, means require bpp * width must be multiples of 8. > + * bpp return width's requirememnt > + * 0 0 none > + * 1 3 8 (need 3 zero bits) > + * 2 2 4 > + * 3 3 8 > + * 4 1 2 > + * 5 3 8 > + * 6 2 4 > + * 7 3 8 This is supposed to be a brief one-line description. The rest of the documentation goes after the argument. Also, have checked the formatting of the generated documentation ? > + * @bpp: input bpp I have no idea if this is a bits per pixel or bytes per pixel value. I'm actually not sure what the function is even supposed to do. It feels it's really a ad-hoc helper, I would like to see it being used in multiple drivers to see if it makes sense. > + * @align: expected alignment, 2^(align). > + * > + * return: required alignment. > + */ > +static inline u32 v4l_get_required_align_by_bpp(u32 bpp, u32 align) > +{ > + int pos; > + > + if (bpp == 0) > + return 0; > + > + pos = ffs(bpp) - 1; > + return pos > align ? 0 : align - pos; > +} > + > #endif /* V4L2_COMMON_H_ */ > -- Regards, Laurent Pinchart