From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8837EC6FA90 for ; Mon, 19 Sep 2022 07:48:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229921AbiISHsh (ORCPT ); Mon, 19 Sep 2022 03:48:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55148 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229877AbiISHse (ORCPT ); Mon, 19 Sep 2022 03:48:34 -0400 Received: from mail-lf1-x130.google.com (mail-lf1-x130.google.com [IPv6:2a00:1450:4864:20::130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D48711E3F7; Mon, 19 Sep 2022 00:48:32 -0700 (PDT) Received: by mail-lf1-x130.google.com with SMTP id s6so34368527lfo.7; Mon, 19 Sep 2022 00:48:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:message-id:in-reply-to:date:subject:cc:to:from :user-agent:references:from:to:cc:subject:date; bh=f/ohHw0zwXo9hGYKmLMjHmAZtp10Il5h/1fQAo577NY=; b=kwtD+gKqOWXSABgVUNVVKnDc1POQMG799g9EpbcabwJbiLT6TRc5joUW1mHjVglvOo 43iAYBtgWvsrHUCF7CZHI3YeVKKUy2RXSvlXPe+GE1CPKUlejamL3Kb3lPnw34bkbpYH A3skcPEPKHHPgOGNrDfXdvBKH0Lga5lBltxPUaNOmi8beSVA7GWPNLGp5G8PbMfJ/BEA xQrjXtxOBI61oxQCmlzQse8mbfimnOHDZWu801jfmIHb70ru8EmsoAee+S1GAgvL1Zrv oOu0b6M/ZziAm71uvVSkTXxsT/hOJzPeiSzsukBEvKDRe/TEVDv3S6FCYNU0X2z+5j7Y i3HA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=mime-version:message-id:in-reply-to:date:subject:cc:to:from :user-agent:references:x-gm-message-state:from:to:cc:subject:date; bh=f/ohHw0zwXo9hGYKmLMjHmAZtp10Il5h/1fQAo577NY=; b=vS0ERzp8fCAQXzmSvdeuG1z1l1ik7URZcU2Y18SgiYA73QINs6OZrTzzsZsMeCVRYg dr1aVZhONGxV0h4lHUsdF5oGbR2ItuSn9/7DZTIExRW4GigMN63+Z9O89W2N8qU+ovQ5 OxVu+qd9yKslzFC70HSn9dHx45AJx8PlaeY7a4wlviQhnPEDEVHI6nIjvjeJQRpijejG lNd730w7F4ogMuQVh8+AiEmnE5ZwGaPZlxbCOg3gADs7VNO8Rx5ZJBkWKF+yyKujxAUp AtLO81CY4WJ8ly6XL0lUGupv8w8RwZhIazbLLVBBczl7SJfw2Bls99lFDAB7ulxz5Vl6 ws4w== X-Gm-Message-State: ACrzQf3XUMJlc6u69eQoVJsT9sTUKJSY+nWh2ebjBc4sLozweEDhONdt +htIB6YLeAnJDaAxTEjuR5JdOFMQM4pOaA== X-Google-Smtp-Source: AMsMyM6HkvoeuUq4NLAon0UbWyTo51sAKFY3An/yw5j4g/uCTIiz4KeCSCh3prxFsKI6EDhiUhYhjA== X-Received: by 2002:a05:6512:3184:b0:49d:6b29:201c with SMTP id i4-20020a056512318400b0049d6b29201cmr5676011lfe.363.1663573710408; Mon, 19 Sep 2022 00:48:30 -0700 (PDT) Received: from razdolb ([37.1.42.233]) by smtp.gmail.com with ESMTPSA id x20-20020a2e9c94000000b0026c5579c64csm40910lji.89.2022.09.19.00.48.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Sep 2022 00:48:29 -0700 (PDT) References: <20220911200147.375198-1-mike.rudenko@gmail.com> <87czbwp9xx.fsf@gmail.com> User-agent: mu4e 1.9.0; emacs 28.2 From: Mikhail Rudenko To: Sakari Ailus Cc: Dave Stevenson , Mauro Carvalho Chehab , Rob Herring , Krzysztof Kozlowski , Hans Verkuil , Jacopo Mondi , Shawn Tu , Jimmy Su , Arnd Bergmann , Arec Kao , Laurent Pinchart , Marek Vasut , linux-media@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 0/2] Add Omnivision OV4689 image sensor driver Date: Mon, 19 Sep 2022 10:01:06 +0300 In-reply-to: Message-ID: <87wn9zreic.fsf@gmail.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sakari, On 2022-09-19 at 06:40 GMT, Sakari Ailus wrote: > Hi Mikhail, > > On Fri, Sep 16, 2022 at 12:27:42AM +0300, Mikhail Rudenko wrote: >> >> Hi Dave, >> >> On 2022-09-14 at 10:58 +01, Dave Stevenson wrote: >> > Hi Mikhail >> > >> > On Sun, 11 Sept 2022 at 21:02, Mikhail Rudenko wrote: >> >> >> >> Hello, >> >> >> >> this series implements support for Omnivision OV4689 image >> >> sensor. The Omnivision OV4689 is a high performance, 1/3-inch, 4 >> >> megapixel image sensor. Ihis chip supports high frame rate speeds up >> >> to 90 fps at 2688x1520 resolution. It is programmable through an I2C >> >> interface, and sensor output is sent via 1/2/4 lane MIPI CSI-2 >> >> connection. >> >> >> >> The driver is based on Rockchip BSP kernel [1]. It implements 4-lane CSI-2 >> >> and single 2688x1520 @ 30 fps mode. The driver was tested on Rockchip >> >> 3399-based FriendlyElec NanoPi M4 board with MCAM400 camera >> >> module. >> >> While porting the driver, I stumbled upon two issues: [snip] >> >> (2) The original driver exposes analog gain range 0x0 - 0x7ff, but the >> >> gain is not linear across that range. Instead, it is piecewise linear >> >> (and discontinuous). 0x0-0xff register values result in 0x-2x gain, >> >> 0x100-0x1ff to 0x-4x, 0x300-0x3ff to 0x-8x, and 0x700-0x7ff to 0x-16x, >> >> with more linear segments in between. Rockchip's camera engine code >> >> chooses one of the above segments depenging on the desired gain >> >> value. The question is, how should we proceed keeping in mind >> >> libcamera use case? Should the whole 0x0-0x7ff be exposed as-is and >> >> libcamera will do the mapping, or the driver will do the mapping >> >> itself and expose some logical gain units not tied to the actual gain >> >> register value? Meanwhile, this driver conservatively exposes only >> >> 0x0-0xf8 gain register range. >> > >> > The datasheet linked above says "for the gain formula, please contact >> > your local OmniVision FAE" :-( >> > I would assume that the range is from 1x rather than 0x - people >> > rarely want a totally black image that 0x would give. Or is it ranges >> > of 1x - 2x, 2x - 4x, 4x - 8x, and 8x - 16x? >> >> A picture is worth a thousand words, so I've attached the results of my >> experimentation with the gain register. They were obtained with Rockchip >> 3399, with AEC, AGC and black level subtraction disabled. The image was >> converted from 10-bit RGGB to 8-bit YUV 4:2:0 by the Rockchip ISP. > > Based on that it looks like their medication may have been a little too > strong. > > Could this be implemented so that the control value would be linear linear > but its range would correspond 1x--16x values? > > libcamera will be able to cope with that. > According to the following fragment of the Rockchip camera engine sensor configuration file for ov4689 [1] [1 2 128 0 1 128 255 2 4 64 -248 1 376 504 4 8 32 -756 1 884 1012 8 16 16 -1784 1 1912 2040] , it uses gain register value range 128-255 for gain 1x-2x, 376-504 for gain 2x-4x, 884-1024 for 4x-8x, and 1912-2040 for 8x-16x. Do you suggest to implement this calculation in the sensor driver and expose some linear "logical" gain to userspace (ranging, e.g., 128-2048 for gains 1x-16x)? [1] https://github.com/aosp-rockchip/android_external_camera_engine_rkaiq/blob/quartz64/iqfiles/ov4689_JSD3425-C1_JSD3425-C1-36IRC-4M-F20.xml -- Best regards, Mikhail