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=-13.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 04429C433E0 for ; Mon, 22 Feb 2021 15:28:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A883364E61 for ; Mon, 22 Feb 2021 15:28:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231792AbhBVP1w (ORCPT ); Mon, 22 Feb 2021 10:27:52 -0500 Received: from relay12.mail.gandi.net ([217.70.178.232]:45619 "EHLO relay12.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231213AbhBVPTc (ORCPT ); Mon, 22 Feb 2021 10:19:32 -0500 Received: from uno.localdomain (93-61-96-190.ip145.fastwebnet.it [93.61.96.190]) (Authenticated sender: jacopo@jmondi.org) by relay12.mail.gandi.net (Postfix) with ESMTPSA id A55D1200002; Mon, 22 Feb 2021 15:18:45 +0000 (UTC) Date: Mon, 22 Feb 2021 16:19:13 +0100 From: Jacopo Mondi To: Laurent Pinchart Cc: Jacopo Mondi , kieran.bingham+renesas@ideasonboard.com, niklas.soderlund+renesas@ragnatech.se, geert@linux-m68k.org, Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 09/16] media: i2c: rdacm21: Re-work OV10640 initialization Message-ID: <20210222151913.a4teevpafzxi2xlz@uno.localdomain> References: <20210216174146.106639-1-jacopo+renesas@jmondi.org> <20210216174146.106639-10-jacopo+renesas@jmondi.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi On Mon, Feb 22, 2021 at 03:27:25AM +0200, Laurent Pinchart wrote: > Hi Jacopo, > > Thank you for the patch. > > On Tue, Feb 16, 2021 at 06:41:39PM +0100, Jacopo Mondi wrote: > > The OV10640 image sensor reset and powerdown on signals are controlled > > s/ on// > > > by the embedded OV490 ISP. The current reset procedure does not respect > > the 1 millisecond power-up delay and releases the reset signal before > > the powerdown one. > > > > Fix the OV10640 power up sequence by releasing the powerdown signal, > > waiting the mandatory 1 millisecond power up delay and then releasing > > the reset signal. The reset delay is not characterized in the chip > > manual if not as "255 XVCLK + initialization". Wait for at least 3 > > milliseconds to guarantee the SCCB bus is available. > > > > This commit fixes a sporadic start-up error triggered by a failure to > > read the OV10640 chip ID: > > rdacm21 8-0054: OV10640 ID mismatch: (0x01) > > > > Signed-off-by: Jacopo Mondi > > --- > > drivers/media/i2c/rdacm21.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/media/i2c/rdacm21.c b/drivers/media/i2c/rdacm21.c > > index b22a2ca5340b..c420a6b96879 100644 > > --- a/drivers/media/i2c/rdacm21.c > > +++ b/drivers/media/i2c/rdacm21.c > > @@ -333,13 +333,15 @@ static int ov10640_initialize(struct rdacm21_device *dev) > > { > > u8 val; > > > > - /* Power-up OV10640 by setting RESETB and PWDNB pins high. */ > > + /* Power-up OV10640 by setting PWDNB and RESETB pins high. */ > > ov490_write_reg(dev, OV490_GPIO_SEL0, OV490_GPIO0); > > ov490_write_reg(dev, OV490_GPIO_SEL1, OV490_SPWDN0); > > ov490_write_reg(dev, OV490_GPIO_DIRECTION0, OV490_GPIO0); > > ov490_write_reg(dev, OV490_GPIO_DIRECTION1, OV490_SPWDN0); > > - ov490_write_reg(dev, OV490_GPIO_OUTPUT_VALUE0, OV490_GPIO0); > > + > > ov490_write_reg(dev, OV490_GPIO_OUTPUT_VALUE0, OV490_SPWDN0); > > Shouldn't this be OV490_GPIO_OUTPUT_VALUE1 ? > Ouch, yes it should > > + usleep_range(1500, 3000); > > + ov490_write_reg(dev, OV490_GPIO_OUTPUT_VALUE0, OV490_GPIO0); > > I'm a bit puzzled by why this patch would improve the ID read issue, > given that it sets GPIO0 to 1, then sets GPIO0 to 1, compared to > previously setting GPIO0 to 1 following by setting GPIO0 to 1 :-) Maybe :) it doesn't make things worse at least! > it's the additional delay ? In any case, it would probably be a good > idea to perform additional tests after fixing this. I think the additional delay plays indeed a role, as it's a requirement in the datasheet that was not respected, but now I'm dead scared to fix this and find out I've opened another can of worms.. > > > usleep_range(3000, 5000); > > > > /* Read OV10640 ID to test communications. */ > > -- > Regards, > > Laurent Pinchart