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[23.128.96.31]) by mx.google.com with ESMTPS id cb4-20020a056a00430400b00690d8405fe6si2802194pfb.317.2023.10.13.00.17.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Oct 2023 00:17:37 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.31 as permitted sender) client-ip=23.128.96.31; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=IVoeRbEx; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.31 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by morse.vger.email (Postfix) with ESMTP id 3CFC480A52B2; Fri, 13 Oct 2023 00:17:35 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at morse.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229901AbjJMHR3 (ORCPT + 99 others); Fri, 13 Oct 2023 03:17:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55078 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229843AbjJMHR2 (ORCPT ); Fri, 13 Oct 2023 03:17:28 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF9DDBC; Fri, 13 Oct 2023 00:17:26 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0115FC433CB; Fri, 13 Oct 2023 07:17:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697181446; bh=mZzYynmfJ2/pdsSnnLB7cuavYnApPnZfzHGYj9nCAeA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=IVoeRbExMYaVYqOlZ0E8lBzZCXXY1JbAget/P8s277Z4fb0gx7WIb1qebIwGCY1IJ h9+RlBxTjpMHU+QGDK+xK0cIE4HpVPEjn3DX8RpRLBXFLTD9DmNZ8Y2xHQAVYmMjxV zytHQGwaKWn4P5a2325k49h7ZiBI2s+N2XYzMt6wM/rVgKre84QrYF0DViIU1ytMd7 VfArELQIqtToaHjPtoTAvY8n3GcR/eoFQMbjTHu1l699yX99pLwFNg9UhFxkHIysst 0uOq71xzAiyIVBIG853S3Os9ftzvPGv/woCU5U6WfkrFesxc9ATonOrZGcWYEdd4GO aK2T7umF31aTQ== Date: Fri, 13 Oct 2023 09:17:23 +0200 From: Wolfram Sang To: Stefan Lengfeld Cc: Krzysztof =?utf-8?Q?Ha=C5=82asa?= , linux-media , lkml , Dave Stevenson , Oleksij Rempel , Pengutronix Kernel Team , Shawn Guo , Sascha Hauer , Fabio Estevam , NXP Linux Team , linux-i2c@vger.kernel.org Subject: Re: Sony IMX290/462 image sensors I2C xfer peculiarity Message-ID: Mail-Followup-To: Wolfram Sang , Stefan Lengfeld , Krzysztof =?utf-8?Q?Ha=C5=82asa?= , linux-media , lkml , Dave Stevenson , Oleksij Rempel , Pengutronix Kernel Team , Shawn Guo , Sascha Hauer , Fabio Estevam , NXP Linux Team , linux-i2c@vger.kernel.org References: <20231011101553.we3r73xejvqdql5j@porty> <20231012220127.GB27838@stcim.de> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="u/l8M5o0YMZg682I" Content-Disposition: inline In-Reply-To: <20231012220127.GB27838@stcim.de> X-Spam-Status: No, score=-1.2 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on morse.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (morse.vger.email [0.0.0.0]); Fri, 13 Oct 2023 00:17:35 -0700 (PDT) --u/l8M5o0YMZg682I Content-Type: text/plain; charset=us-ascii Content-Disposition: inline > Do you know the I2C repeated start feature [1]? This allows to batch together > multiple I2C read/writes in a single transfer. And in the best case, this > transfer is executed in one go without a delay in between. At least in the > kernel it's guaranteed that no other driver can go in between with another > transfer. If the HW does rep_start properly, it is even guaranteed on the bus because the bus is never seen as free by other participants. Check "START and STOP" conditions in the I2C specs. --u/l8M5o0YMZg682I Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEOZGx6rniZ1Gk92RdFA3kzBSgKbYFAmUo7wMACgkQFA3kzBSg KbZs4xAAiGla3VYW4LK+tWuDufXr/zrNHbwb0pU1zty0q+93Yp9riCln24vQ8VdN QbtOpwcHb+aZOh5wfz8IqL8DTgAtC1Z5h2qxUXv2vYA/V6t5jirybkOg/iR+moG4 61V8ov437G4iAaL4xcObmtW6F6Gse/dlm8Q2JGg2eVIZqNr7mgcgJeyPTR38pWjS 1FjP9NYoY1Xu/JhFEwar2LbLLYQqNtrT1AuPXAll2GlfDrBtfxSWZAG6ywDIXU34 oEaMuAZDVIzhltMLgXzBQhMgef9l0naVuo/myB+htVwA7oAn45ImyDc1fGyAUMlC x2E7zL54CYGpon4FclA74Sgp0AjlWa3RWCkPZ+oQzL7HyjKYwM62cb3aPWkMCaV7 57KkLtKwUb5SmTRGryNYivEXta7adBo7HvIrYeuO0paGDw65NpzeKP4rMSQHo+XX LWTirx18kOKA4T+r9xKvIdKiDly+R26dBln6nK5cbM2bkmIn6TIo7i2fITPbTInA Y94MFb/0Ifa97tNRD0VQbv89dnzogx0HP8BkVqwdpshIoIifmYSm9X33n5Nb0cT1 YifunACQYgdt3vxnJjFPiUB3KE8Px/Wp/vvkWEacvbgnxfrID8zVMAhhsvinCrhQ hHh/id1kvsXrsrs8POeU0KrsQDarFZUAf42lJtPcXoY2rd9FoBU= =pVqj -----END PGP SIGNATURE----- --u/l8M5o0YMZg682I--