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 367843D69; Fri, 16 May 2025 06:05:15 +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=1747375516; cv=none; b=V8ESPRoYk+sbhFBHBUK2VBJy7rffIGqQjVStHI3AMfL8PLvSIt06eVqCAfols/7P1DXFgszpxoX1sBAV8e67s9KUatNj+VkAu2MPRXEYd8pA+bGl4jhh0kZ8DZHIRavFZjj+IRpf+5QBZAETFUkuBQoencS5nhOzqB+SbzX6FM8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747375516; c=relaxed/simple; bh=bW/BSRnMonxJF09QI4JenGAMerZbgvhvGxO91qgyG40=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=VOphZKlnLgw/79GV3Lph1Hi+BciqmXwL6mfNqhkTrN+B/SXFicW6oUW63qqhlrGTmvRno6m+uIfpTvOgzeJ8ACkD9Ft0xrD5wxgmlUu8O7nt4+MK3HVasU7/Yi3SgnvOLaahmPdto2UaQgMEUIjHa5//w/IVD7WDFrPKdxPLqHc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=n96Sx2Ok; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="n96Sx2Ok" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48F3CC4CEE4; Fri, 16 May 2025 06:05:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1747375515; bh=bW/BSRnMonxJF09QI4JenGAMerZbgvhvGxO91qgyG40=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=n96Sx2OkenwE0kt3YDNfJZlohnuKTqmaWZNUPaZ6CW9WiQIYMcAet01BF7Nfw3kVN lOe4k+swNbvlzFY+wtcQDBtvSfiaHZFM9SHTbiH/S2Xt53BToRxnP4jbJiE6g/IUD0 wo3hmk8y+YdB/EGpRIQ112qAOTUPNhzYaOs8yXBE= Date: Fri, 16 May 2025 08:03:27 +0200 From: Greg KH To: Kuninori Morimoto Cc: Linux-Kernel , devicetree@vger.kernel.org, shimoda , goda , Kurokawa , Kihara , kazuya.mizuguchi.ks@renesas.com, takamitsu.honda.pv@renesas.com Subject: Re: Question about UIO vs DT Message-ID: <2025051649-commode-brussels-1034@gregkh> References: <87o6vutrbw.wl-kuninori.morimoto.gx@renesas.com> <2025051549-flannels-lively-a46d@gregkh> <871pspti1t.wl-kuninori.morimoto.gx@renesas.com> Precedence: bulk X-Mailing-List: devicetree@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: <871pspti1t.wl-kuninori.morimoto.gx@renesas.com> On Fri, May 16, 2025 at 02:18:07AM +0000, Kuninori Morimoto wrote: > > Hi Greg > > Thank you for the reply > > > > For example in case of > > > the device which needs "2 regs 3 irqs". it will be > > > > > > (A) [1 reg, 1 IRQ] UIO > > > (B) [1 reg, 1 IRQ] UIO > > > (C) [0 reg, 1 IRQ] UIO > > > > > > and (C) will be DT error. Is this known issue ? Do we have better solution ? > > > > Yes, write a real driver for the device as obviously it is a complex one > > and UIO shouldn't be used for it :) > > > > What type of device is this that requires this type of hardware control > > and why do you feel that UIO is the proper solution? > > One of big reason is license. > Because it needs to be proprietary licensed driver, we can't create > real driver. That is not a valid reason at all, sorry. So much so that I, and many others, have argued that you can not have UIO drivers in userspace that are NOT also released under the GPLv2. Go work with your lawyers please, there's nothing I can now do to help you out with this due to the expectation that you are attempting to evade the license requirements here. greg k-h