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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 6E557C5ACC1 for ; Fri, 13 Mar 2020 21:23:57 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0DE1620752 for ; Fri, 13 Mar 2020 21:23:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="V2NvY5Lw"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="cScPnew9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0DE1620752 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Yey+ZKG3MLUxPAuScoDYCfc1kyIj372s5TsGUnVpeuA=; b=V2NvY5LwZH5w9J jDYtr5uAkE5P/EoUMqE8cKznTFc+aPP3lnXCTQnFNpOubQYlX/JPLVjE44RFsVfTIZfyFh/iIfgey 0Ris6fzA6r4RmAO7JUqoby40Nl8JfXpCdtIEiVD43nGlmzbecupqs6fwLvIo2JtsZya+HGtTnTDuC CtO9aEtc6RzTP55M8MY7A7g/gd3IFLqC9qUcxiCRgMT+c8qBwDD/2EyfNSNtxsMbkD5JpQBxfmLuq fPQhS4tqAEJMsRv1/cE8Qajt6XemwOLDmJvBxPJaJgAQBYQmvWbOIj46T4o5aoHn6z5Fr6iuhyX9u 7R4gED69YQBDnYJ3co6g==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jCrmc-0003pg-4b; Fri, 13 Mar 2020 21:23:54 +0000 Received: from perceval.ideasonboard.com ([2001:4b98:dc2:55:216:3eff:fef7:d647]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jCrmZ-0003ob-3r for linux-arm-kernel@lists.infradead.org; Fri, 13 Mar 2020 21:23:52 +0000 Received: from pendragon.ideasonboard.com (81-175-216-236.bb.dnainternet.fi [81.175.216.236]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 589F32D6; Fri, 13 Mar 2020 22:23:49 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1584134629; bh=IMhiV5Vz2k3pdowwWoR/Qmpwd2H11u0gvTUhvGhrkpA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cScPnew9RSEDN1y6Bo/x86i3wEKy0MJ4GhQWNbCMn/G/d8Q7+Wr/Jet/KQ1ZmdV9y AYjE1YhPmlrrIW0zAfFtOVVL+dI1jLg0ST/7YW0uLCu87SJvE5gu0c7+EIH6fhmMSM AEnyqZCGg3arV/tDA+KNWVeSmY1Z6qTa2N14cSGk= Date: Fri, 13 Mar 2020 23:23:45 +0200 From: Laurent Pinchart To: Lad Prabhakar Subject: Re: [PATCH v3 3/4] media: i2c: ov5645: Set maximum leverage of external clock frequency to 24480000 Message-ID: <20200313212345.GM4751@pendragon.ideasonboard.com> References: <1584133954-6953-1-git-send-email-prabhakar.mahadev-lad.rj@bp.renesas.com> <1584133954-6953-4-git-send-email-prabhakar.mahadev-lad.rj@bp.renesas.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1584133954-6953-4-git-send-email-prabhakar.mahadev-lad.rj@bp.renesas.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200313_142351_309950_3C257C06 X-CRM114-Status: GOOD ( 18.14 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , devicetree@vger.kernel.org, Fabio Estevam , Sakari Ailus , Ezequiel Garcia , Sascha Hauer , Magnus Damm , linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org, Rob Herring , Geert Uytterhoeven , NXP Linux Team , Pengutronix Kernel Team , Mauro Carvalho Chehab , Shawn Guo , linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Prabhakar, Thank you for the patch. On Fri, Mar 13, 2020 at 09:12:33PM +0000, Lad Prabhakar wrote: > While testing on Renesas RZ/G2E platform, noticed the clock frequency to > be 24242424 as a result the probe failed. However increasing the maximum > leverage of external clock frequency to 24480000 fixes this issue. Since > this difference is small enough and is insignificant set the same in the > driver. > > Signed-off-by: Lad Prabhakar > --- > drivers/media/i2c/ov5645.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c > index 4fbabf3..b49359b 100644 > --- a/drivers/media/i2c/ov5645.c > +++ b/drivers/media/i2c/ov5645.c > @@ -1107,8 +1107,10 @@ static int ov5645_probe(struct i2c_client *client) > } > > xclk_freq = clk_get_rate(ov5645->xclk); > - /* external clock must be 24MHz, allow 1% tolerance */ > - if (xclk_freq < 23760000 || xclk_freq > 24240000) { > + /* external clock must be 24MHz, allow a minimum 1% and a maximum of 2% > + * tolerance So where do these numbers come from ? I understand that 2% is what you need to make your clock fit in the range, but why -1%/+2% instead of -2%/+2% ? And why not 2.5 or 3% ? The sensor datasheet documents the range of supported xvclk frequencies to be 6MHz to 54MHz. I understand that PLL parameters depend on the clock frequency, but could they be calculated instead of hardcoded, to avoid requiring an exact 24MHz input frequency ? > + */ > + if (xclk_freq < 23760000 || xclk_freq > 24480000) { > dev_err(dev, "external clock frequency %u is not supported\n", > xclk_freq); > return -EINVAL; -- Regards, Laurent Pinchart _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel