From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753619AbcBCNrZ (ORCPT ); Wed, 3 Feb 2016 08:47:25 -0500 Received: from mout.kundenserver.de ([212.227.126.134]:58834 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751944AbcBCNrY (ORCPT ); Wed, 3 Feb 2016 08:47:24 -0500 From: Arnd Bergmann To: Zubair Lutfullah Kakakhel Cc: tj@kernel.org, hdegoede@redhat.com, david.daney@cavium.com, aleksey.makarov@caviumnetworks.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org Subject: Re: [PATCH v6] SATA: OCTEON: support SATA on OCTEON platform Date: Wed, 03 Feb 2016 14:47:03 +0100 Message-ID: <2782231.XGO9cUTm7n@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.16.0-10-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: <56B1FF7A.3040906@imgtec.com> References: <1454437485-48009-1-git-send-email-Zubair.Kakakhel@imgtec.com> <1930324.vU65IL0x0g@wuerfel> <56B1FF7A.3040906@imgtec.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:7ylaHZTn7eK3UP+2n2Jcy1aDkzVa4B9eYdHAmEllmFpywXyWGVN Blzd4YTdEF0AEhAp2XV6mMBPGCFsluv94R62JzNwLmSQLGGCKJ4UdzBN/kk6iRd/cQEdPwX BsvL3clbrlMmzXNFEoC8UDPy+6cy2EecJ/1azaaSIHzYK6wKlHOHFLVjBTDRmpRx4WbpNSC 48x3xKJb3maFZK3AKgHmg== X-UI-Out-Filterresults: notjunk:1;V01:K0:bqWAnY93Fmo=:JNEwKnz6On9TKO7GWe/wOt JHI8A30WiJt+KIOKEAd/vVax6LVP+G0IoYUANxg4UryM1nlMNJ49HAfQkYKjPdXfS+/9k5rq7 NS17hM5PimU/+X1AXe1Qvoh+4oW7VMIRVujJIY5E2cBjdpphmwKa6A6IcWro4I/UxT6e4tXRw ynILVN5CpwJCZP5cPGFma8qwCE7YYQmKvcm1fPsTK3E8Wi1UXZ52HGm1PdT8kNj6vOyGlmYqB K6GPlJ9cQh96Q9nnlGfRxtaboImQwC5iP85SmMI5N1H7ma9n+KbuOs31j+suFRpDoslVEqbUE DtHTwrPF9MjrLwaCSj5KOWw5xVghnMtN12eV9ysHA6bB2I+USOBCwFjfRIAkBUygJ70G1BwMT OGWjlpF/+syxZYgpVBT0Ofdb0T8qNKTTFzymw3HYheM7wFMXiFgWFQkByWBh6nbFS9TjO5otp xh6+ixUyFo3q4IN6JuQTMzd/p5DJx47jX8CPfIBA6ITDcotHAFDwQKZUaPldB3Gxt+1uYKsx7 U5zWEcSl6uR5UxYQA/USo5Q/BUb1qnA/CFQYgMb0Kgep2t8/DJ+VhfcJgIeGeCeHLUQ12ZAJm DOKESiPRAWSmtihqtyUc1DxwkVuNnZNg5vZVAdWJlmBgYbCbAySpfYHXQMaRcXCArpugBh1ia QyVssxvCHP3sL5bUBzFX956HJ/F6RKd+hrTzS8waZcwwyz2xTlnmBfFDv27aB3x7Z22SK01Ez 4AlXLc08tQW3xOCQ Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 03 February 2016 13:24:10 Zubair Lutfullah Kakakhel wrote: > > Typically we treat those special registers as part of the device itself > > and have a single device node for the AHCI controller and that one. > > > > What is your reason for doing it differently here? > > Two reasons > > 1- The hardware is like a proper split rather than additional hidden registers in > the same memory space. > > 2- Tons of devices in the field have the following DT node built in the bootloader. > > uctl@118006c000000 { > compatible = "cavium,octeon-7130-sata-uctl"; > reg = <0x11800 0x6c000000 0x0 0x100>; > ... > sata: sata@16c0000000000 { > compatible = "cavium,octeon-7130-ahci"; > reg = <0x16c00 0x00000000 0x0 0x200>; > ... > }; > }; > > The patch suggests a way to handle this. > Ok, fair enough. Also, you write in the binding that this is a bus bridge, so this indeed matches what the hardware does, and that's ok. Does the bus bridge actually translate the entire 64-bit CPU MMIO space, or is it possible that it only handles one device (or a couple of them) with a fairly limited space? Maybe it's better to represent it as a #address-cells=<1> in the example, and have the child device appear at address 0 in there. For the machines that already ship a DT, that would not matter though, it works either way. Arnd