From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EE355CCA473 for ; Thu, 30 Jun 2022 21:00:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236356AbiF3VAq (ORCPT ); Thu, 30 Jun 2022 17:00:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51776 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231290AbiF3VAm (ORCPT ); Thu, 30 Jun 2022 17:00:42 -0400 Received: from ssl.serverraum.org (ssl.serverraum.org [176.9.125.105]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 56CEE4D15C; Thu, 30 Jun 2022 14:00:41 -0700 (PDT) Received: from ssl.serverraum.org (web.serverraum.org [172.16.0.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ssl.serverraum.org (Postfix) with ESMTPSA id 3E15522236; Thu, 30 Jun 2022 23:00:37 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=walle.cc; s=mail2016061301; t=1656622837; 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=GTq9btX49e5m0sHPzYxeKQ7Uls84RHJVy8UQyM+UM8A=; b=ItoMZoyefxT3MZJQUuqoJungzv5DfQ3AS7XH6+UKt/7YkBckqSB1Le3Zes3vqUivhnYZgb t5HdLmGbNNcWbSiHZ5RKcNhyiImpM7tQ8aRVo5SRmcX/v6oqxb7+rul4AlW/oeAnBFFrZ9 j/wpJJna3ICu9q5NCQBOKVV2RKgxIwI= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Thu, 30 Jun 2022 23:00:37 +0200 From: Michael Walle To: Horatiu Vultur Cc: Andy Shevchenko , Krzysztof Kozlowski , Andy Shevchenko , "Rafael J. Wysocki" , Rob Herring , Krzysztof Kozlowski , ACPI Devel Maling List , devicetree , Linux Kernel Mailing List , Vladimir Oltean Subject: Re: fwnode_for_each_child_node() and OF backend discrepancy In-Reply-To: <20220630201617.sqpihcevym7sxqng@soft-dev3-1.localhost> References: <9e58f421c27121977d11381530757a6e@walle.cc> <3ab8afab-b6b7-46aa-06d4-6740cee422d7@linaro.org> <288f56ba9cfad46354203b7698babe91@walle.cc> <96f40ae6abf76af3b643b1e1c60d1d9f@walle.cc> <20220628205254.gnllvaz7w5jmpfe5@soft-dev3-1.localhost> <4782de1fc6692a98bd6c267c2714325f@walle.cc> <20220630201617.sqpihcevym7sxqng@soft-dev3-1.localhost> User-Agent: Roundcube Webmail/1.4.13 Message-ID: X-Sender: michael@walle.cc Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 2022-06-30 22:16, schrieb Horatiu Vultur: > The 06/28/2022 23:07, Michael Walle wrote: >> EXTERNAL EMAIL: Do not click links or open attachments unless you know >> the content is safe >> >> Am 2022-06-28 22:52, schrieb Horatiu Vultur: >> > The 06/28/2022 22:28, Andy Shevchenko wrote: >> > > EXTERNAL EMAIL: Do not click links or open attachments unless you know >> > > the content is safe >> > > >> > > On Tue, Jun 28, 2022 at 5:17 PM Krzysztof Kozlowski >> > > wrote: >> > > > On 28/06/2022 17:09, Michael Walle wrote: >> > >> > Hi, >> > >> > Sorry for joint this late. >> > >> > > >> > > ... >> > > >> > > > > Mh. Assume a SoC with an integrated ethernet switch. Some ports >> > > > > are externally connected, some don't. I'd think they should be disabled, >> > > > > no? Until now, all bindings I know, treat them as disabled. But OTOH >> > > > > you still need to do some configurations on them, like disable port >> > > > > forwarding, disable them or whatever. So the hardware is present, but >> > > > > it is not connected to anything. >> > > > >> > > > I see your point and the meaning is okay... except that drivers don't >> > > > touch disabled nodes. If a device (with some address space) is disabled, >> > > > you do not write there "please be power off". Here the case is a bit >> > > > different, because I think ports do not have their own address space. >> > > > Yet it contradicts the logic - something is disabled in DT and you >> > > > expect to perform actual operations on it. >> > > >> > > You beat me up to this comment, I also see a contradiction of what >> > > "disabled" means in your, Michael, case and what it should be. >> > > >> > > If you need to perform an operation on some piece of HW, it has not to >> > > be disabled. >> > > >> > > Or, you may deduce them by knowing how many ports in hardware (this is >> > > usually done not by counting the nodes, but by a property) and do >> > > whatever you want on ones, you have not listed (by port_num) in the >> > > array of parsed children. >> > >> > It is not possible to have a defined for the MAX number of ports that >> > supported by lan966x. Which is 8. And assigned that define to >> > num_phys_ports instead of counting the entries in DT? >> >> You mean also for the lan9662? I'm pretty sure that doesn't >> work. Have a look where num_phys_ports is used. One random >> example: >> https://elixir.bootlin.com/linux/latest/source/drivers/net/ethernet/microchip/lan966x/lan966x_main.c#L874 >> >> So if your switch only has 4 ports, then I'd guess you'll >> access a non-existing register. > > Underneath lan662 and lan668 is the same chip. The HW people disable > some ports/features on each platform but from what I know you will > still > be able to access the registers. I noticed that there are still 8 ports in the register description and assumed that it was wrong [1]. But ok, that makes sense in some way. OTOH that means, we cannot do the guesswork Vladimir proposed. -michael [1] https://microchip-ung.github.io/lan9662_reginfo/reginfo_LAN9662.html