From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from avon.wwwdotorg.org ([70.85.31.133]:49587 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754262AbbFQB2p (ORCPT ); Tue, 16 Jun 2015 21:28:45 -0400 Message-ID: <5580CD4B.70003@wwwdotorg.org> Date: Tue, 16 Jun 2015 19:28:43 -0600 From: Stephen Warren MIME-Version: 1.0 To: =?UTF-8?B?Tm9yYWxmIFRyw7hubmVz?= CC: linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-watchdog@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/3] watchdog: bcm2835: Add poweroff code for the Raspberry Pi References: <1434195541-28368-1-git-send-email-noralf@tronnes.org> <1434195541-28368-2-git-send-email-noralf@tronnes.org> <557F930E.8010002@wwwdotorg.org> <557FEECE.9060909@tronnes.org> In-Reply-To: <557FEECE.9060909@tronnes.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-watchdog-owner@vger.kernel.org List-Id: linux-watchdog@vger.kernel.org On 06/16/2015 03:39 AM, Noralf Trønnes wrote: > > Den 16.06.2015 05:07, skrev Stephen Warren: >> On 06/13/2015 05:39 AM, Noralf Trønnes wrote: >>> This adds a new poweroff function to the watchdog driver for the >>> Raspberry Pi. Currently poweroff/halt results in a reboot. >>> >>> The Raspberry Pi firmware uses the RSTS register to know which >>> partiton to boot from. The partiton value is spread into bits >>> 0, 2, 4, 6, 8, 10. Partiton 63 is a special partition used by >>> the firmware to indicate halt. >>> >>> The firmware made this change in 19 Aug 2013 and was matched >>> by the downstream commit: >>> Changes for new NOOBS multi partition booting from gsh >> I don't understand why we need a new compatible value here; why not >> simply modify the existing bcm2835_power_off() function. That is written >> to do something that's interpreted by the RPi firmware, not something >> that the bcm2835 HW does. >> >> Admittedly the current name is a bit misleading, but fixing that should >> be a separate change to fixing the implementation to do what the current >> firmware expects. > > There are other boards that use the BCM2835 and I didn't want to break the > behaviour for those that use the reference firmware. We don't support those other board in mainline Linux AFAIK. In other discussions, Eric Anholt stated that the Roku 2 for example doesn't use the same firmware (albeit they were derived from the same base a long way back apparently) so I have no good reason to believe this logic is a standard across difference bcm2835 devices. Do you know more specific details? > Roku 2 device uses > this soc, and changing bcm2835_power_off() would break support for it. > ODROID-W also use BCM2835, but this is a Pi clone so I don't know if they > have matched their firmware behaviour to that of the Pi (admittedly not > many boards were made, their source of chips went dry).