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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 48DE0CAC5B3 for ; Thu, 25 Sep 2025 15:55:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Cc:To:In-Reply-To:References :Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=fx1rtVvxrvGc/iVOVfsa66+7d0bmu+/1vZpxztNNK8Y=; b=ETB0uA54svdSWaesXzkn04dsmr 16/1b4kR1ISzQ5AqLgO/qb05ww5o49FvRerffs5GGFQpZqHtEIKkQ1lyY5a0Ur9pkdBJjeWSDogbS UFe4P342WLslxsuCTUqC0d9RyvC4QQc1SHIr2d8nmLkjze3n8U78QVZQaowAzwAwr3WHN5JHRxrn2 hNCg2X4nkO+lnif6AoSRdda11NwBW5H3VE+rD3B1Um15n3lZq+mGH3pgs+ID/0UgB8g0MMOfCavfT I+mQso9acaaUnpylPW+HQ/TY8ei/5MTZZcGNGuf/pUxg1LhJeAvY3IITmUkPyRKmWZClEXMojQ5mT OGgZsiAg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1v1oJi-0000000AshS-1uNF; Thu, 25 Sep 2025 15:55:34 +0000 Received: from perceval.ideasonboard.com ([213.167.242.64]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1v1oJf-0000000AsZd-0500 for linux-arm-kernel@lists.infradead.org; Thu, 25 Sep 2025 15:55:32 +0000 Received: from [127.0.1.1] (cpc89244-aztw30-2-0-cust6594.18-1.cable.virginm.net [86.31.185.195]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 628B21D1C; Thu, 25 Sep 2025 17:54:01 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1758815642; bh=0eohwAR/y++4oPMxRnpqozTlsghcWn2K5MPx0wPe8gg=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=mcs2YirOd9cwzKG03SPsBv9Hu8SCoekmPeGuYhxWzmjddYDdUZlXWueul6Gl41IYx OlSU4tm4LTT8NyUg7pGfK2BAw7s9Sznpt2dx178Xg0suyV0meuVCt35XXyToGzG51e Xy1ALGMN1+X/f0UGnFoTTnMuTD/J6JnE42tAkOCY= From: Isaac Scott Date: Thu, 25 Sep 2025 16:54:26 +0100 Subject: [PATCH v4 1/4] media: v4l: Add helper to get number of active lanes via a pad MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20250925-active-data-lanes-v4-1-8b54e3d5af6c@ideasonboard.com> References: <20250925-active-data-lanes-v4-0-8b54e3d5af6c@ideasonboard.com> In-Reply-To: <20250925-active-data-lanes-v4-0-8b54e3d5af6c@ideasonboard.com> To: Mauro Carvalho Chehab , Rui Miguel Silva , Laurent Pinchart , Martin Kepplinger , Purism Kernel Team , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Sakari Ailus Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, Isaac Scott , Frank Li X-Mailer: b4 0.13.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250925_085531_519718_6120981A X-CRM114-Status: GOOD ( 17.80 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Sometimes, users will not use all of the MIPI CSI 2 lanes available when connecting to the MIPI CSI receiver of their device. Add a helper function that checks the mbus_config for the device driver to allow users to define the number of active data lanes through the get_mbus_config op. If the driver does not implement this op, fall back to using the maximum number of lanes available. Reviewed-by: Frank Li Reviewed-by: Laurent Pinchart Signed-off-by: Isaac Scott --- drivers/media/v4l2-core/v4l2-common.c | 29 +++++++++++++++++++++++++++++ include/media/v4l2-common.h | 20 ++++++++++++++++++++ 2 files changed, 49 insertions(+) diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c index b367d479d6b3..2b4cec25e751 100644 --- a/drivers/media/v4l2-core/v4l2-common.c +++ b/drivers/media/v4l2-core/v4l2-common.c @@ -573,6 +573,35 @@ s64 v4l2_get_link_freq(const struct media_pad *pad, unsigned int mul, return v4l2_get_link_freq_ctrl(sd->ctrl_handler, mul, div); } EXPORT_SYMBOL_GPL(v4l2_get_link_freq); + +unsigned int v4l2_get_active_data_lanes(const struct media_pad *pad, + unsigned int max_data_lanes) +{ + struct v4l2_mbus_config mbus_config = {}; + struct v4l2_subdev *sd; + unsigned int lanes; + int ret; + + sd = media_entity_to_v4l2_subdev(pad->entity); + ret = v4l2_subdev_call(sd, pad, get_mbus_config, pad->index, + &mbus_config); + if (ret < 0 && ret != -ENOIOCTLCMD) + return ret; + + /* This relies on the mbus_config being zeroed at init time */ + lanes = mbus_config.bus.mipi_csi2.num_data_lanes; + if (!lanes) + return max_data_lanes; + + if (lanes > max_data_lanes) { + dev_dbg(sd->dev, "Active data lanes (%u) exceeds max (%u)\n", + lanes, max_data_lanes); + return -EINVAL; + } + + return lanes; +} +EXPORT_SYMBOL_GPL(v4l2_get_active_data_lanes); #endif /* diff --git a/include/media/v4l2-common.h b/include/media/v4l2-common.h index 5c0a7f6b5bb6..950df46cb27a 100644 --- a/include/media/v4l2-common.h +++ b/include/media/v4l2-common.h @@ -581,6 +581,26 @@ int v4l2_fill_pixfmt_mp(struct v4l2_pix_format_mplane *pixfmt, u32 pixelformat, #ifdef CONFIG_MEDIA_CONTROLLER s64 v4l2_get_link_freq(const struct media_pad *pad, unsigned int mul, unsigned int div); + +/** + * v4l2_get_active_data_lanes - Get number of active data lanes from driver + * + * @pad: The transmitter's media pad. + * @max_data_lanes: The maximum number of active data lanes supported by + * the MIPI CSI link in hardware. + * + * This function is intended for obtaining the number of data lanes that are + * actively being used by the driver for a MIPI CSI-2 device on a given media pad. + * This information is derived from a mbus_config fetched from a device driver + * using the get_mbus_config v4l2_subdev pad op. + * + * Return: + * * >0: Number of active data lanes + * * %-EINVAL: Number of active data lanes is invalid, as it exceeds the maximum + * supported data lanes. + */ +unsigned int v4l2_get_active_data_lanes(const struct media_pad *pad, + unsigned int max_data_lanes); #endif void v4l2_simplify_fraction(u32 *numerator, u32 *denominator, -- 2.43.0