From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 930D323F40F for ; Fri, 25 Apr 2025 10:13:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745576001; cv=none; b=Y5GtyjChC3OvZZ9R332E6k1y0PQ4piWljm0yR6IR5yUOzoNhV8mUVzIw5pQFnKsDeIb+hgR1J+eOtdLkqfYRgneO38V9cOm/5bt1HJs5fEUjA1caqCepv+JVqmUZFdFQFNvJzmvT+tZjncMPLDqugrne8iaCbjZKgL9cw63puqk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745576001; c=relaxed/simple; bh=R9HHXp4+WPKRcDY98kPzN+e6xRzDIvxgQM+D3RFQeyQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gN0XY6akSHL2NuhswEOOIkbPha8I4zo+zx53FODEq16I0aNnCSuVbBlPCD2OVbDeI3xma36gtV3CTHfMA87tdjoX8ms1UY9RFL1gVEPddKztPyY/QKjyL9XTHMDyW75DL0k/5HrNKaUEAbKKMxMO8CyQ5u4HmwT/qbvjXJca4gE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=SiQ4dqG3; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="SiQ4dqG3" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1745575996; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=pw9QCpCjs2zCbHjb9QyW1AL2e3Rd0H7rcNPzyrHOhpk=; b=SiQ4dqG37qMaxQCEesgPw2rJVj6c8zT/3o/wlC8PbcZFqQ+ikCU2EDGXdO7PQzxAqwB8zI 0Ii1lqGJWnpdlioKVOpR63YC+ypdkJuKnDNk0ImINn0FUKLMpUbYejiKTrVqK0APgK9tvy 6IRDrDlJv0kgCKtaHBK5KjYO+BQLzXo= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-371-rj20FwBbPbS_Gr9fXFYPqQ-1; Fri, 25 Apr 2025 06:13:13 -0400 X-MC-Unique: rj20FwBbPbS_Gr9fXFYPqQ-1 X-Mimecast-MFC-AGG-ID: rj20FwBbPbS_Gr9fXFYPqQ_1745575991 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9C49D1956088; Fri, 25 Apr 2025 10:13:10 +0000 (UTC) Received: from [10.44.33.33] (unknown [10.44.33.33]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 6B11A195608D; Fri, 25 Apr 2025 10:13:05 +0000 (UTC) Message-ID: <98e471cc-ec66-4c89-af9a-57625c0c2873@redhat.com> Date: Fri, 25 Apr 2025 12:13:03 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v4 5/8] mfd: zl3073x: Add functions to work with register mailboxes To: Lee Jones Cc: Andrew Lunn , netdev@vger.kernel.org, Vadim Fedorenko , Arkadiusz Kubalewski , Jiri Pirko , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Prathosh Satish , Kees Cook , Andy Shevchenko , Andrew Morton , Michal Schmidt , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org References: <20250424154722.534284-1-ivecera@redhat.com> <20250424154722.534284-6-ivecera@redhat.com> <5094e051-5504-48a5-b411-ed1a0d949eeb@lunn.ch> <458254c7-da05-4b27-870d-08458eb89ba6@redhat.com> <98ae9365-423c-4c7e-8b76-dcea3762ce79@lunn.ch> <7d96b3a4-9098-4ffa-be51-4ce5dd64a112@redhat.com> <20250425065558.GP8734@google.com> Content-Language: en-US From: Ivan Vecera In-Reply-To: <20250425065558.GP8734@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 On 25. 04. 25 8:55 dop., Lee Jones wrote: > On Thu, 24 Apr 2025, Ivan Vecera wrote: > >> >> >> On 24. 04. 25 9:29 odp., Andrew Lunn wrote: >>>> Yes, PHC (PTP) sub-driver is using mailboxes as well. Gpio as well for some >>>> initial configuration. >>> >>> O.K, so the mailbox code needs sharing. The question is, where do you >>> put it. >> >> This is crucial question... If I put the MB API into DPLL sub-driver >> then PTP sub-driver will depend on it. Potential GPIO sub-driver as >> well. >> >> There could be some special library module to provide this for >> sub-drivers but is this what we want? And if so where to put it? > > MFD is designed to take potentially large, monolithic devices and split > them up into smaller, more organised chunks, then Linusify them. This > way, area experts (subsystem maintainers) get to concern themselves only > with the remit to which they are most specialised / knowledgable. MFD > will handle how each of these areas are divided up and create all of the > shared resources for them. On the odd occasion it will also provide a > _small_ API that the children can use to talk to the parent device. > > However .... some devices, like yours, demand an API which is too > complex to reside in the MFD subsystem itself. This is not the first > time this has happened and I doubt it will be the last. My first > recommendation is usually to place all of the comms in drivers/platform, > since, at least in my own mind, if a complex API is required, then the > device has become almost platform-like. There are lots of examples of > H/W comm APIs in there already for you to peruse. OK, I will do it differently... Will drop MB API at all from MFD and just expose the additional mutex from MFD for multi-op access. Mailboxes will be handled directly by sub-devices. Short description: MFD exposes: zl3073x_{read,write}_u{8,16,32,48}() & zl3073x_poll_u8() - to read/write/poll registers - they checks that multiop_lock is taken when caller is accessing registers from Page 10 and above zl3073x_multiop_{lock,unlock}() - to protect operation where multiple reads, writes and poll is required to be done atomically Is this OK for you? Thanks, Ivan