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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 60A43C10F14 for ; Thu, 3 Oct 2019 07:17:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 39F6E20842 for ; Thu, 3 Oct 2019 07:17:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727796AbfJCHRU (ORCPT ); Thu, 3 Oct 2019 03:17:20 -0400 Received: from retiisi.org.uk ([95.216.213.190]:39174 "EHLO hillosipuli.retiisi.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725879AbfJCHRU (ORCPT ); Thu, 3 Oct 2019 03:17:20 -0400 Received: from valkosipuli.localdomain (valkosipuli.retiisi.org.uk [IPv6:2a01:4f9:c010:4572::80:2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by hillosipuli.retiisi.org.uk (Postfix) with ESMTPS id 9D432634C87; Thu, 3 Oct 2019 10:16:47 +0300 (EEST) Received: from sailus by valkosipuli.localdomain with local (Exim 4.92) (envelope-from ) id 1iFvLy-0002Ge-4R; Thu, 03 Oct 2019 10:16:46 +0300 Date: Thu, 3 Oct 2019 10:16:46 +0300 From: Sakari Ailus To: Manivannan Sadhasivam Cc: mchehab@kernel.org, robh+dt@kernel.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, c.barrett@framos.com, a.brela@framos.com Subject: Re: [PATCH v3 2/3] media: i2c: Add IMX290 CMOS image sensor driver Message-ID: <20191003071646.GZ896@valkosipuli.retiisi.org.uk> References: <20190830091943.22646-1-manivannan.sadhasivam@linaro.org> <20190830091943.22646-3-manivannan.sadhasivam@linaro.org> <20190923092209.GL5525@valkosipuli.retiisi.org.uk> <20191001184200.GA7739@Mani-XPS-13-9360> <20191002103715.GR896@valkosipuli.retiisi.org.uk> <20191003053338.GA7868@Mani-XPS-13-9360> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191003053338.GA7868@Mani-XPS-13-9360> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Manivannan, On Thu, Oct 03, 2019 at 11:03:38AM +0530, Manivannan Sadhasivam wrote: .... > > > > > +static int imx290_set_gain(struct imx290 *imx290, u32 value) > > > > > +{ > > > > > + int ret; > > > > > + > > > > > + u32 adjusted_value = (value * 10) / 3; > > > > > > > > What's the purpose of this? Why not to use the value directly? > > > > > > > > > > The gain register accepts the value 10/3 of the actual gain required. Hence, > > > we need to manually do the calculation before updating the value. I can > > > add a comment here to clarify. > > > > It's better to use the register value directly. Otherwise the granularity > > won't be available to the user space. > > > > The sensor datasheet clearly defines that the 10/3'rd of the expected gain > should be set to this register. So, IMO we should be setting the value as The unit of that gain is decibels, but the controls do not have a unit. Register value is really preferred here. > mentioned in the datasheet. I agree that we are missing the userspace > granularity here but sticking to the device limitation shouldn't be a problem. > As I said, I'll add a comment here to clarify. The comment isn't visible in the uAPI. > > > > > > > > > + > > > > > + ret = imx290_write_buffered_reg(imx290, IMX290_GAIN, 1, adjusted_value); > > > > > + if (ret) > > > > > + dev_err(imx290->dev, "Unable to write gain\n"); > > > > > + > > > > > + return ret; > > > > > +} > > > > > + > > > > > +static int imx290_set_power_on(struct imx290 *imx290) > > > > > +{ > > > > > + int ret; > > > > > + > > > > > + ret = clk_prepare_enable(imx290->xclk); > > > > > > > > Please move the code from this function to the runtime PM runtime suspend > > > > callback. The same for imx290_set_power_off(). > > > > > > > > > > May I know why? I think since this is being used only once, you're suggesting > > > to move to the callback function itself but please see the comment below. I > > > will reuse this function to power on the device during probe. > > > > Yes, you can call the same function from probe, even if it's used as a > > runtime PM callback. > > > > There's no need to have a function that acts as a wrapper for calling it > > with a different type of an argument. > > > > You mean directly calling imx290_runtime_resume() from probe is fine? Yes. Feel free to call it e.g. imx290_power_on or something. -- Regards, Sakari Ailus