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 X-Spam-Level: X-Spam-Status: No, score=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4657DC43381 for ; Mon, 25 Feb 2019 13:06:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 16AF020842 for ; Mon, 25 Feb 2019 13:06:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727085AbfBYNGM (ORCPT ); Mon, 25 Feb 2019 08:06:12 -0500 Received: from relay2-d.mail.gandi.net ([217.70.183.194]:46609 "EHLO relay2-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727042AbfBYNGM (ORCPT ); Mon, 25 Feb 2019 08:06:12 -0500 X-Originating-IP: 90.88.23.190 Received: from localhost (aaubervilliers-681-1-81-190.w90-88.abo.wanadoo.fr [90.88.23.190]) (Authenticated sender: maxime.ripard@bootlin.com) by relay2-d.mail.gandi.net (Postfix) with ESMTPSA id 01F3B40002; Mon, 25 Feb 2019 13:06:06 +0000 (UTC) Date: Mon, 25 Feb 2019 14:06:06 +0100 From: Maxime Ripard To: Jacopo Mondi Cc: Benoit Parrot , Mauro Carvalho Chehab , Laurent Pinchart , "linux-media@vger.kernel.org" , Thomas Petazzoni , Mylene Josserand , Hans Verkuil , Sakari Ailus , Hugues Fruchet , Loic Poulain , Samuel Bobrowicz , Steve Longerbeam , Daniel Mack Subject: Re: [PATCH v4 05/12] media: ov5640: Compute the clock rate at runtime Message-ID: <20190225130606.wax6gmzivxwt5nlk@flea> References: <20181011092107.30715-1-maxime.ripard@bootlin.com> <20181011092107.30715-6-maxime.ripard@bootlin.com> <20190221162020.keonztyi7yq2a4hg@ti.com> <20190222143959.gothnp6namn2gt2w@flea> <20190222145456.3v6lsslj7slb2kob@ti.com> <20190222150421.ilg62fyvrxwp2moh@flea> <20190225092151.pra7mvgvpvekth7z@uno.localdomain> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="oanyiruk7kgpgp7k" Content-Disposition: inline In-Reply-To: <20190225092151.pra7mvgvpvekth7z@uno.localdomain> User-Agent: NeoMutt/20180716 Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org --oanyiruk7kgpgp7k Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Feb 25, 2019 at 10:21:51AM +0100, Jacopo Mondi wrote: > Hello Maxime, Benoit, > sorry for chiming in, but I'm a bit confused... >=20 > On Fri, Feb 22, 2019 at 04:04:21PM +0100, Maxime Ripard wrote: > > On Fri, Feb 22, 2019 at 08:54:56AM -0600, Benoit Parrot wrote: > > > Maxime Ripard wrote on Fri [2019-Feb-22 1= 5:39:59 +0100]: > > > > On Thu, Feb 21, 2019 at 10:20:20AM -0600, Benoit Parrot wrote: > > > > > Hi Maxime, > > > > > > > > > > A couple of questions, > > > > > > > > > > Maxime Ripard wrote on Thu [2018-Oct-= 11 04:21:00 -0500]: > > > > > > The clock rate, while hardcoded until now, is actually a functi= on of the > > > > > > resolution, framerate and bytes per pixel. Now that we have an = algorithm to > > > > > > adjust our clock rate, we can select it dynamically when we cha= nge the > > > > > > mode. > > > > > > > > > > > > This changes a bit the clock rate being used, with the followin= g effect: > > > > > > > > > > > > +------+------+------+------+-----+-----------------+----------= ------+-----------+ > > > > > > | Hact | Vact | Htot | Vtot | FPS | Hardcoded clock | Computed = clock | Deviation | > > > > > > +------+------+------+------+-----+-----------------+----------= ------+-----------+ > > > > > > | 640 | 480 | 1896 | 1080 | 15 | 56000000 | 614= 30400 | 8.84 % | > > > > > > | 640 | 480 | 1896 | 1080 | 30 | 112000000 | 1228= 60800 | 8.84 % | > > > > > > | 1024 | 768 | 1896 | 1080 | 15 | 56000000 | 614= 30400 | 8.84 % | > > > > > > | 1024 | 768 | 1896 | 1080 | 30 | 112000000 | 1228= 60800 | 8.84 % | > > > > > > | 320 | 240 | 1896 | 984 | 15 | 56000000 | 559= 69920 | 0.05 % | > > > > > > | 320 | 240 | 1896 | 984 | 30 | 112000000 | 1119= 39840 | 0.05 % | > > > > > > | 176 | 144 | 1896 | 984 | 15 | 56000000 | 559= 69920 | 0.05 % | > > > > > > | 176 | 144 | 1896 | 984 | 30 | 112000000 | 1119= 39840 | 0.05 % | > > > > > > | 720 | 480 | 1896 | 984 | 15 | 56000000 | 559= 69920 | 0.05 % | > > > > > > | 720 | 480 | 1896 | 984 | 30 | 112000000 | 1119= 39840 | 0.05 % | > > > > > > | 720 | 576 | 1896 | 984 | 15 | 56000000 | 559= 69920 | 0.05 % | > > > > > > | 720 | 576 | 1896 | 984 | 30 | 112000000 | 1119= 39840 | 0.05 % | > > > > > > | 1280 | 720 | 1892 | 740 | 15 | 42000000 | 420= 02400 | 0.01 % | > > > > > > | 1280 | 720 | 1892 | 740 | 30 | 84000000 | 840= 04800 | 0.01 % | > > > > > > | 1920 | 1080 | 2500 | 1120 | 15 | 84000000 | 840= 00000 | 0.00 % | > > > > > > | 1920 | 1080 | 2500 | 1120 | 30 | 168000000 | 1680= 00000 | 0.00 % | > > > > > > | 2592 | 1944 | 2844 | 1944 | 15 | 84000000 | 1658= 62080 | 49.36 % | > > > > > > +------+------+------+------+-----+-----------------+----------= ------+-----------+ > > > > > > > > > > Is the computed clock above the same for both parallel and CSI2? > > > > > > > > > > I want to add controls for PIXEL_RATE and LINK_FREQ, would you ha= ve any > > > > > quick pointer on taking the computed clock and translating that i= nto the > > > > > PIXEL_RATE and LINK_FREQ values? > > > > > > > > > > I am trying to use this sensor with TI CAL driver which at the mo= ment uses > > > > > the PIXEL_RATE values in order to compute ths_settle and ths_term= values > > > > > needed to program the DPHY properly. This is similar in behavior = as the way > > > > > omap3isp relies on this info as well. > > > > > > > > I haven't looked that much into the csi-2 case, but the pixel rate > > > > should be the same at least. > > > > > > I'll have to study the way the computed clock is actually calculated = for > > > either case, but if they yield the same number then I would be surpri= sed > > > that the pixel rate would be the same as in parallel mode you get 8 d= ata > > > bits per clock whereas in CSI2 using 2 data lanes you get 4 data bits= per > > > clock. > > > > The bus rate will be different, but the pixel rate is the same: you > > have as many pixels per frames and as many frames per seconds in the > > parallel and CSI cases. > > >=20 > I agree with that, but.. >=20 > > > So just to be certain here the "Computed clock" column above would be= the > > > pixel clock frequency? > > > > it is >=20 > ...it seems to me the Computed clock column is actually the "byte clock". >=20 > From a simple calculation for the 640x480@15FPS case: > "Computed clock" =3D 1896 * 1080 * 15 * 2 =3D 61430400 >=20 > While, in my understanding, the pixel clock would just be > pixel_clock =3D HTOT * VTOT * FPS =3D 1896 * 1080 * 15 =3D 30715200 >=20 > So I suspect the "* 2" there is the number of bytes per pixel. >=20 > That would match what's also reported here > file:///home/jmondi/project/renesas/linux/linux-build/Documentation/outpu= t/media/kapi/csi2.html?highlight=3Dlink_freq >=20 > Where: > link_freq =3D (pixel_rate * bpp) / (2 * nr_lanes) >=20 > So if I were to calculate PIXEL_RATE and LINK_FREQ in this driver, > that would be: > PIXEL_RATE =3D mode->vtot * mode->htot * ov5640_framerates[sensor->curren= t_fr]; > LINK_FREQ =3D PIXEL_RATE * 16 / ( 2 * sensor->ep.bus.mipi_csi2.num_data_l= anes); > (assuming, as the driver does now, all formats have 16bpp) >=20 > Does this match your understanding as well? You're totally right, sorry about that :) Maxime --=20 Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com --oanyiruk7kgpgp7k Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRcEzekXsqa64kGDp7j7w1vZxhRxQUCXHPoPgAKCRDj7w1vZxhR xZFtAQDzDPfgCQTLIlF8Qp6sSWDfeDlaQ4K/OHALIEDkOoej0AD+ImDwmLFmcoyh EGKSUKF/sONHnSb562NraGnnxq0vQQg= =PZ+g -----END PGP SIGNATURE----- --oanyiruk7kgpgp7k--