From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 2D8101E7C2B; Tue, 11 Mar 2025 08:20:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741681226; cv=none; b=Hpg04h+VN/kWjTsqkE91oe6Qcayh93DiZWGFDNy7YKJsYaN00owM2Jj5TnxEiaEYC+TnkLKtNogW7yZJUyrAf//ihOO6lQFRnX0GZ7STdm/1MGhEQp8of4407RaQUpzgesYBbhEaXOVntwsqn0bDzkGjZR+IcqeSwQRmMM/h19c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741681226; c=relaxed/simple; bh=gaGVYX0NNOaIcaCq6wPZv9fxpNdPOdTR8URu/LPwxus=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=D+TGFLUClvDa3XKL6Gbx1jOBWpGfGFPT35BwWY5IGV5UXkr77A9hOnuxMABSnQdmVidxii6pwYKd8FxFwhn2EpfIc2APxubtqb3FTBymeTrogPQ9egvKZS07dzwLT2qxfP4fuW/vZ6V/DW2DT1d66/rjCLPRir0ZeD5vUKvVfSc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DPTHEgBE; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DPTHEgBE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9E64AC4CEEF; Tue, 11 Mar 2025 08:20:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1741681225; bh=gaGVYX0NNOaIcaCq6wPZv9fxpNdPOdTR8URu/LPwxus=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=DPTHEgBEaigvAitgVNeQ5F6kP2BP+sjQkfPwZ+DWbHyC//fBTuj280Ds7/H5uor4d y+AMnjeIRniwEOdALym7aNeBUhyrdbQmVzbN8MNmVTUoHLIhbIS6YmBlcXQls2XubU fUnx1tygHDYNSX5khc094R3JZV5FQnMhwrKjM/o9q5MOcn6wTTtJ9Pm2nBPJLqL7Kz aIemnq76eJpcetTu9JAS0kVRZchzJUD129eGUBbLB/ETZt/QWF8hBqcMsSZ8ULNrbb u9F6WaICJVWRvsg6kshqgK8BP7xEDURWa/kDsbNU2UAiI1zRzhVsV9n0SgNXoKcLNx E3ZyD2tAqmEFg== Received: from johan by xi.lan with local (Exim 4.97.1) (envelope-from ) id 1truqa-000000004FQ-16rC; Tue, 11 Mar 2025 09:20:20 +0100 Date: Tue, 11 Mar 2025 09:20:20 +0100 From: Johan Hovold To: Marco Felsch Cc: Greg Kroah-Hartman , Rob Herring , Jiri Slaby , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org Subject: Re: [PATCH 0/3] USB-Serial serdev support Message-ID: References: <20240807-v6-10-topic-usb-serial-serdev-v1-0-ed2cc5da591f@pengutronix.de> <20241001072453.3xv5sqxaj4zjprnz@pengutronix.de> <2024100109-maker-ravine-7c65@gregkh> <20241028225702.tdtfqzhm335vvuv5@pengutronix.de> Precedence: bulk X-Mailing-List: linux-usb@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: <20241028225702.tdtfqzhm335vvuv5@pengutronix.de> On Mon, Oct 28, 2024 at 11:57:02PM +0100, Marco Felsch wrote: > On 24-10-01, Greg Kroah-Hartman wrote: > > On Tue, Oct 01, 2024 at 09:24:53AM +0200, Marco Felsch wrote: > > > gentle ping as this is series is two months old now. > > > > And it was rejected as serdev does not support hotplug which of course, > > usb-serial does. > > I hoped to get some feedback on my answer [1]. Regarding hotplug > support: serdev _requires_ some sort of firmware like OF (not sure if it > does work with ACPI too). That said, if serdev finds no firmware a > fallback is provided to the standard serial handling. It's devices going away not being supported which is the main concern. The serdev ttyport implementation does not implement hangup() which is used for serial port tear down. > The firmware could either be added directly by the platform OF file or > via OF-overlays. By making use of overlays we could gain some kind of > hotplug: Once a usb devices was detected and the driver has an > overlay, the overlay gets applied and the probe continues, like we do it > for PCIe devices now [2]. For devices which don't have a registered > overlay the standard usb-serial setup is done by exposing the serial > interface to the userspace. Then it would also be nice to have a way to describe hotplugged devices on the fly, and overlays could indeed be used for that. But that's a separate story. Johan