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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 98363C433E9 for ; Mon, 15 Mar 2021 21:45:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7592564F51 for ; Mon, 15 Mar 2021 21:45:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233643AbhCOVof (ORCPT ); Mon, 15 Mar 2021 17:44:35 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:41634 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233604AbhCOVoM (ORCPT ); Mon, 15 Mar 2021 17:44:12 -0400 Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 5FDED316; Mon, 15 Mar 2021 22:44:10 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1615844650; bh=PDnq21KTjYKfjxP5VoiNl8fnnSBXMC/DE5GGMXNiVuk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=OYkn4KI+cCvcUYpt8GakGxRWN4fbmTkKCaStwlxtmCEScquMhvDH+yr1wvVCxfz7C PlbPWCjuh94ouAndzfjbJRruUBtfVZiBoZjuV5szeCsupJu8Z/HwWOv3wvb1HNemxb Ukr6QN3B5oEU59T0T8ivFHy+nWYeeKF+rB5htffk= Date: Mon, 15 Mar 2021 23:43:34 +0200 From: Laurent Pinchart To: Jacopo Mondi Cc: 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 v2 09/18] media: i2c: max9271: Introduce wake_up() function Message-ID: References: <20210315131512.133720-1-jacopo+renesas@jmondi.org> <20210315131512.133720-10-jacopo+renesas@jmondi.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210315131512.133720-10-jacopo+renesas@jmondi.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jacopo, Thank you for the patch. On Mon, Mar 15, 2021 at 02:15:03PM +0100, Jacopo Mondi wrote: > The MAX9271 chip manual prescribes a delay of 5 milliseconds > after the chip exists from low power state. I don't think we'll ever try to access the chip within 5ms of the beginning of its existence. s/exists/exits/ :-) > Add a new function to the max9271 library driver that wakes up the chip > with a dummy i2c transaction and implements the correct delay of 5 > milliseconds after the chip exits from low power state. > > Use the newly introduced function in the rdacm20 and rdacm21 camera > drivers. The former was not respecting the required delay while the > latter was waiting for a too-short timeout. > > Do not handle the initial i2c address configuration in the library > driver function as the camera module drivers control address > reprogramming. Isn't the initial address fixed though ? Nonetheless, this can be addressed separately, so Reviewed-by: Laurent Pinchart > Signed-off-by: Jacopo Mondi > --- > drivers/media/i2c/max9271.c | 7 +++++++ > drivers/media/i2c/max9271.h | 9 +++++++++ > drivers/media/i2c/rdacm20.c | 2 +- > drivers/media/i2c/rdacm21.c | 3 +-- > 4 files changed, 18 insertions(+), 3 deletions(-) > > diff --git a/drivers/media/i2c/max9271.c b/drivers/media/i2c/max9271.c > index 2c7dc7fb9846..f7bfe7266763 100644 > --- a/drivers/media/i2c/max9271.c > +++ b/drivers/media/i2c/max9271.c > @@ -80,6 +80,13 @@ static int max9271_pclk_detect(struct max9271_device *dev) > return -EIO; > } > > +void max9271_wake_up(struct max9271_device *dev) > +{ > + i2c_smbus_read_byte(dev->client); > + usleep_range(5000, 8000); > +} > +EXPORT_SYMBOL_GPL(max9271_wake_up); > + > int max9271_set_serial_link(struct max9271_device *dev, bool enable) > { > int ret; > diff --git a/drivers/media/i2c/max9271.h b/drivers/media/i2c/max9271.h > index d78fb21441e9..dc5e4e70ba6f 100644 > --- a/drivers/media/i2c/max9271.h > +++ b/drivers/media/i2c/max9271.h > @@ -85,6 +85,15 @@ struct max9271_device { > struct i2c_client *client; > }; > > +/** > + * max9271_wake_up() - Wake up the serializer by issuing an i2c transaction > + * @dev: The max9271 device > + * > + * This function shall be called before any other interaction with the > + * serializer. > + */ > +void max9271_wake_up(struct max9271_device *dev); > + > /** > * max9271_set_serial_link() - Enable/disable serial link > * @dev: The max9271 device > diff --git a/drivers/media/i2c/rdacm20.c b/drivers/media/i2c/rdacm20.c > index b9aaa0f7db42..2265ef7c65d4 100644 > --- a/drivers/media/i2c/rdacm20.c > +++ b/drivers/media/i2c/rdacm20.c > @@ -459,7 +459,7 @@ static int rdacm20_initialize(struct rdacm20_device *dev) > > /* Verify communication with the MAX9271: ping to wakeup. */ > dev->serializer.client->addr = MAX9271_DEFAULT_ADDR; > - i2c_smbus_read_byte(dev->serializer.client); > + max9271_wake_up(&dev->serializer); > > /* Serial link disabled during config as it needs a valid pixel clock. */ > ret = max9271_set_serial_link(&dev->serializer, false); > diff --git a/drivers/media/i2c/rdacm21.c b/drivers/media/i2c/rdacm21.c > index 179d107f494c..7bce55adfd7c 100644 > --- a/drivers/media/i2c/rdacm21.c > +++ b/drivers/media/i2c/rdacm21.c > @@ -452,8 +452,7 @@ static int rdacm21_initialize(struct rdacm21_device *dev) > > /* Verify communication with the MAX9271: ping to wakeup. */ > dev->serializer.client->addr = MAX9271_DEFAULT_ADDR; > - i2c_smbus_read_byte(dev->serializer.client); > - usleep_range(3000, 5000); > + max9271_wake_up(&dev->serializer); > > /* Enable reverse channel and disable the serial link. */ > ret = max9271_set_serial_link(&dev->serializer, false); -- Regards, Laurent Pinchart