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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 319E2C433EF for ; Mon, 27 Sep 2021 08:55:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0A6F86113A for ; Mon, 27 Sep 2021 08:55:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233507AbhI0I5X (ORCPT ); Mon, 27 Sep 2021 04:57:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36690 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230439AbhI0I5W (ORCPT ); Mon, 27 Sep 2021 04:57:22 -0400 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 03D9FC061575 for ; Mon, 27 Sep 2021 01:55:43 -0700 (PDT) Received: from [192.168.1.111] (91-158-153-130.elisa-laajakaista.fi [91.158.153.130]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 3B8CDB91; Mon, 27 Sep 2021 10:55:41 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1632732941; bh=Er8Ib1yciCurvUf2k9+RC/HYu96K0Bnst8gn2zF3xaY=; h=To:Cc:References:From:Subject:Date:In-Reply-To:From; b=CQnsJj7xOQxIEZEKoOWTiTkTSQavDE33IHMLGFseHzaAIdgXASeUGaap7eak54Rxd wWghabq+7DVBEQQ0+dcmqAwEG9+NfjTaAgFeJrQmP2WYKGAIudjV6Sq9KjDntocy02 LxJDeWxGy43U+PHYuKwVzazPYY53Aoy9UVVgk8cc= To: Laurent Pinchart Cc: Jacopo Mondi , linux-media@vger.kernel.org, sakari.ailus@linux.intel.com, Jacopo Mondi , niklas.soderlund+renesas@ragnatech.se, Mauro Carvalho Chehab , Hans Verkuil , Pratyush Yadav , Lokesh Vutla References: <20210830110116.488338-1-tomi.valkeinen@ideasonboard.com> <20210830110116.488338-4-tomi.valkeinen@ideasonboard.com> <20210913114154.ovffxjoghgdud4js@uno.localdomain> <0733ae28-bcd9-6dc8-fb6a-0fa43beb1191@ideasonboard.com> <20210913133841.nck65h2ft4hfnbg5@uno.localdomain> <656577a3-b783-0272-4809-20169b84e891@ideasonboard.com> <20210916130752.bsdhq3xpsatdfl4a@uno.localdomain> From: Tomi Valkeinen Subject: Re: [PATCH v8 03/36] media: subdev: add 'which' to subdev state Message-ID: <9d80e73b-acd0-9439-8447-6c2a66686ec3@ideasonboard.com> Date: Mon, 27 Sep 2021 11:55:38 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On 27/09/2021 03:48, Laurent Pinchart wrote: > Hi Tomi, > > On Thu, Sep 16, 2021 at 04:24:19PM +0300, Tomi Valkeinen wrote: >> On 16/09/2021 16:07, Jacopo Mondi wrote: >> >>> Also note that operations like s_stream do not take a state as >>> parameter. The driver has to fetch it from the subdev anyway >>> (this in reply to the idea of having the active state as parameter vs >>> retrieving it from the subdev if ACTIVE) >>> >>> While porting the R-Car drivers on top of this series I found myself >>> in the need to (in the s_stream call chain) >>> >>> static int rcsi2_start_receiver(struct rcar_csi2 *priv) >>> { >>> const struct v4l2_subdev_state *state = priv->subdev.state; >>> const struct v4l2_subdev_stream_configs *configs = &state->stream_configs; >>> >>> ... >>> >>> /* >>> * Configure field handling inspecting the formats of the >>> * single sink pad streams. >>> */ >>> for (i = 0; i < configs->num_configs; ++i) { >>> const struct v4l2_subdev_stream_config *config = configs->configs; >>> if (config->pad != RCAR_CSI2_SINK) >>> continue; >>> >>> if (config->fmt.field != V4L2_FIELD_ALTERNATE) >>> continue; >>> >>> fld |= FLD_DET_SEL(1); >>> fld |= FLD_FLD_EN(config->stream); >>> >>> /* PAL vs NTSC. */ >>> if (config->fmt.height == 240) >>> fld |= FLD_FLD_NUM(0); >>> else >>> fld |= FLD_FLD_NUM(1); >>> } >>> >>> ... >>> >>> } >>> >>> Am I doing it wrong, or is this a case for the subdev to have to >>> directly access sd->state ? >> >> In s_stream path you should: >> >> state = v4l2_subdev_lock_active_state(sd); >> >> >> >> v4l2_subdev_unlock_state(state); >> >> If you already have the state, e.g. in set_fmt: >> >> state = v4l2_subdev_validate_and_lock_state(sd, state); >> >> >> >> v4l2_subdev_unlock_state(state); >> >> Accessing the stream_configs directly is fine but not that nice. I did >> think about some helpers, perhaps for_each_stream_config(), but I didn't >> add that as I didn't have the need. >> >> There's v4l2_state_get_stream_format() which can be used in many cases, >> but we probably need something else if you need to iterate over all the >> configs. > > I really like forcing drivers to call functions that will lock the > state, at least until we can move the locks to the core (if ever). We > should move the fields of v4l2_subdev that drivers are not supposed to > access directly under a big PRIVATE comment. Can you clarify what you mean here? Did you mean you like functions that will _check_ the lock? Or did you just mean that you like v4l2_subdev_lock_state() better than mutex_lock(state->lock)? Well, in any case, I think my series does both =). I can add the private comment to subdev. In fact, at one time I did not have sd->state, but sd->_state, just to make sure no one accesses it. Tomi