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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D4C62C54EE9 for ; Tue, 20 Sep 2022 08:41:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231403AbiITIlS (ORCPT ); Tue, 20 Sep 2022 04:41:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46676 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231406AbiITIks (ORCPT ); Tue, 20 Sep 2022 04:40:48 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9571F13DCD for ; Tue, 20 Sep 2022 01:39:35 -0700 (PDT) Received: from ptx.hi.pengutronix.de ([2001:67c:670:100:1d::c0]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1oaYmb-0005c5-NA; Tue, 20 Sep 2022 10:39:09 +0200 Received: from mfe by ptx.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1oaYma-0001Ji-JI; Tue, 20 Sep 2022 10:39:08 +0200 Date: Tue, 20 Sep 2022 10:39:08 +0200 From: Marco Felsch To: Sakari Ailus Cc: Laurent Pinchart , mchehab@kernel.org, robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org, kishon@ti.com, vkoul@kernel.org, hverkuil@xs4all.nl, jacopo@jmondi.org, kieran.bingham+renesas@ideasonboard.com, linux-media@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-phy@lists.infradead.org, kernel@pengutronix.de Subject: Re: [PATCH v2 4/4] media: tc358746: add Toshiba TC358746 Parallel to CSI-2 bridge driver Message-ID: <20220920083908.st4h3pb6usn4zavu@pengutronix.de> References: <20220916134535.128131-1-m.felsch@pengutronix.de> <20220916134535.128131-5-m.felsch@pengutronix.de> <20220919171142.6av6ap5gwweldado@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716 X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c0 X-SA-Exim-Mail-From: mfe@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: devicetree@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Hi Sakari, On 22-09-19, Sakari Ailus wrote: > On Mon, Sep 19, 2022 at 08:37:23PM +0300, Laurent Pinchart wrote: > > > > > + ctrl = v4l2_ctrl_new_int_menu(&tc358746->ctrl_hdl, NULL, > > > > > + V4L2_CID_LINK_FREQ, 0, 0, > > > > > > > > Shouldn't the max argument be set to the number of items minus 1 ? > > > > > > Right now I would keep it that way since the driver only supports one > > > link-frequencies setting. So the ctrl don't let the userspace assume > > > that there are more than one link-frequency. > > > > Good point. Can you add a short comment above the call to explain this ? > > Wouldn't it be just easier to do what Laurent suggested originally? The end > result is the same, isn't it, and no comment needed? The end result depends on the device-tree given "link-frequencies" property. The driver currently takes only one frequency but the system-integrator of course can specify many more. In such case the 1st is used. If I go with Laurent's comment, all frequencies would be shown to the user-space but IMHO this shouldn't be the case since the driver supports only 1 frequency. > > > > > > > + link_frequencies); > > > > > + if (ctrl) > > > > > + ctrl->flags |= V4L2_CTRL_FLAG_READ_ONLY; > > Now that this is a bridge, this value presumably doesn't need to change. The value can change, e.g. if you have a few freq. to allow a wide range of frame sizes. This can be the case to conform the emv tests. So there can be a freq. for smaller frame sizes and one for larger frame sizes. > There will just be more blanking if the source sub-device pixel rate is > slower, right? Please see above. Regards, Marco