From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 58CBA4F1E4; Wed, 27 Mar 2024 10:46:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.19 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711536394; cv=none; b=NE98hxO12mdZT5Sh3e66GxVignkcImza4Bj5pLIZzxH5oSdBP3zzIJvPi/4u3meTVSVmNJl7UbjvE/wsGxWIHoAFgpfzF/MrlyEl+afATn3I29z/Hhjw7YXGvMLso7aBXBqHUvyt2iKKcfPYj0b3JHMh0wBpD6fVvQtD2Aglv2Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711536394; c=relaxed/simple; bh=OSEX0ZaauFn6+aQhM6O8E2hHzie5j9+agUDTBkTWpRg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mBHvKJn4T4hpGHSaFgTTz7KI3TFLmswHybRiLoGBivoops5zfQ6b0UMwXGdq4hifbfszYs5HgAHg4Pvz6cOZ4OLoJ4pNFLHjJIs2WdjyijKW3sa2wYuVaDgPV5/wt5he8ksrAYhw7G9E2oHq/UFS/xAmrLUl/97fqiirc2lK6AU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=AXRALpN2; arc=none smtp.client-ip=192.198.163.19 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="AXRALpN2" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1711536392; x=1743072392; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=OSEX0ZaauFn6+aQhM6O8E2hHzie5j9+agUDTBkTWpRg=; b=AXRALpN2BnPSzB43O8531YIvOeTKMJJZZdfSRkqybb46LRGccZ3K0iCP 7cKhGFUu2lNzM5OHW1B8gglUSvWDDFKyMZdYH1MU56Wt0AD5nhlZAPjNc 1xXUzzP3KAj+bYNcZ+EGB+OsSiJVX5i4raEXEGqD8UT3+YeCqwx7RlCqo StyeRwKU9KCgsB+RC9od3B5iiFbWT5ZSHn/TjsNmtHCuX4TtIh/+v/fuo 6bnEAgfnQ0FV7EhdQdKxL+Yrdl3JICGjVJwKtaiG8egwJVQpYrn4SlQSa vyvERLZui7yrKRg8BtFQ388Ev5DBHURAo2pzfiFXMre0v/fpuNd52C2J3 A==; X-CSE-ConnectionGUID: Drmrxh+sTlmm5tMGjE6XnA== X-CSE-MsgGUID: LlFT6kmvRkuWg+tFS1eWfg== X-IronPort-AV: E=McAfee;i="6600,9927,11025"; a="6492004" X-IronPort-AV: E=Sophos;i="6.07,158,1708416000"; d="scan'208";a="6492004" Received: from fmviesa009.fm.intel.com ([10.60.135.149]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Mar 2024 03:46:32 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,158,1708416000"; d="scan'208";a="16316580" Received: from turnipsi.fi.intel.com (HELO kekkonen.fi.intel.com) ([10.237.72.44]) by fmviesa009-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Mar 2024 03:46:30 -0700 Received: from kekkonen.localdomain (localhost [127.0.0.1]) by kekkonen.fi.intel.com (Postfix) with SMTP id 5F2BB11FB81; Wed, 27 Mar 2024 12:46:27 +0200 (EET) Date: Wed, 27 Mar 2024 10:46:27 +0000 From: Sakari Ailus To: Tomi Valkeinen Cc: Laurent Pinchart , Mauro Carvalho Chehab , Hans Verkuil , Umang Jain , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] media: v4l2-subdev: Support enable/disable_streams for single-pad subdevs Message-ID: References: <20240325-single-pad-enable-streams-v1-1-142e19896a72@ideasonboard.com> <20240325125055.GC23988@pendragon.ideasonboard.com> <0ad9841d-bb51-4512-9388-f9ce36372677@ideasonboard.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Heippa, On Mon, Mar 25, 2024 at 07:56:46PM +0200, Tomi Valkeinen wrote: > On 25/03/2024 19:52, Sakari Ailus wrote: > > Moi, > > > > On Mon, Mar 25, 2024 at 03:43:01PM +0200, Tomi Valkeinen wrote: > > > On 25/03/2024 15:02, Sakari Ailus wrote: > > > > Moi, > > > > > > > > Thanks for the patch. > > > > > > > > On Mon, Mar 25, 2024 at 02:50:55PM +0200, Laurent Pinchart wrote: > > > > > Hi Tomi, > > > > > > > > > > On Mon, Mar 25, 2024 at 02:43:23PM +0200, Tomi Valkeinen wrote: > > > > > > Currently a subdevice with a single pad, e.g. a sensor subdevice, must > > > > > > use the v4l2_subdev_video_ops.s_stream op, instead of > > > > > > v4l2_subdev_pad_ops.enable/disable_streams. This is because the > > > > > > enable/disable_streams machinery requires a routing table which a subdev > > > > > > cannot have with a single pad. > > > > > > > > > > > > Implement enable/disable_streams support for these single-pad subdevices > > > > > > by assuming an implicit stream 0 when the subdevice has only one pad. > > > > > > > > > > > > Signed-off-by: Tomi Valkeinen > > > > > > --- > > > > > > Even though I did send this patch, I'm not sure if this is necessary. > > > > > > s_stream works fine for the subdevs with a single pad. With the upcoming > > > > > > internal pads, adding an internal pad to the subdev will create a > > > > > > routing table, and enable/disable_streams would get "fixed" that way. > > > > > > > > I'd like to get rid of a redundant way to control streaming. > > > > > > We can't get rid of it anyway, can we? We're not going to convert old > > > drivers to streams. > > > > I'd expect to do that but it'd take a long time. That being said, I think > > we need to consider devices without pads (VCMs) so it may well be this > > would remain after all. > > > > > > > > For new drivers, yes, we shouldn't use s_stream. But is the answer for new > > > sensor drivers this patch, or requiring an internal pad? > > > > For new drivers I'd like to see an internal pad in fact. > > {enable,disable}_streams is still internal to the kernel. > > So, you think this patch should be dropped? No, no. Not all sub-device drivers with pads are camera sensor drivers. :-) > > > > > > > So perhaps the question is, do we want to support single-pad subdevs in > > > > > > the future, in which case something like this patch is necessary, or > > > > > > will all modern source subdev drivers have internal pads, in which > > > > > > case this is not needed... > > > > > > > > > > I think the latter would be best. I however can't guarantee we won't > > > > > have valid use cases for (enable|disable)_streams on single-pad subdevs > > > > > though, so you patch could still be interesting. > > > > > > > > Instead of the number of pads, could we use instead the > > > > V4L2_SUBDEV_FL_STREAMS flag or whether g_routing op is supported to > > > > determine the need for this? > > > > > > Maybe, but are they better? Do you see some issue with checking for the > > > number of pads? I considered a few options, but then thought that the most > > > safest test for this case is 1) one pad 2) enable/disable_streams > > > implemented. > > > > I think I'd actually prefer {enable,disable}_streams in fact. > > Hmm, sorry, now I'm confused =). What do you mean with that? I'd use V4L2_SUBDEV_FL_STREAMS flag instead of the number of pads. The number of pads is less related to routing. -- Regards, Sakari Ailus