Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752872AbdLLXh7 (ORCPT ); Tue, 12 Dec 2017 18:37:59 -0500 Received: from foss.arm.com ([217.140.101.70]:50808 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752762AbdLLXhy (ORCPT ); Tue, 12 Dec 2017 18:37:54 -0500 Subject: Re: [PATCH v5 4/9] drivers: base cacheinfo: Add support for ACPI based firmware tables To: "Rafael J. Wysocki" Cc: "Rafael J. Wysocki" , ACPI Devel Maling List , "linux-arm-kernel@lists.infradead.org" , Sudeep Holla , Hanjun Guo , Lorenzo Pieralisi , Will Deacon , Catalin Marinas , Greg Kroah-Hartman , Viresh Kumar , Mark Rutland , Linux Kernel Mailing List , Linux PM , jhugo@codeaurora.org, wangxiongfeng2@huawei.com, Jonathan.Zhang@cavium.com, Al Stone , Jayachandran.Nair@cavium.com, austinwc@codeaurora.org, Len Brown References: <20171201222330.18863-1-jeremy.linton@arm.com> <20171201222330.18863-5-jeremy.linton@arm.com> <2078459.JrYtfXc8fv@aspire.rjw.lan> <5024a041-2ef4-3912-994f-b5fcc945e916@arm.com> <9bb1c58a-8d48-9952-e292-60b2bcb87a51@arm.com> From: Jeremy Linton Message-ID: Date: Tue, 12 Dec 2017 17:37:48 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2360 Lines: 69 On 12/12/2017 05:02 PM, Rafael J. Wysocki wrote: > On Tue, Dec 12, 2017 at 11:55 PM, Jeremy Linton wrote: >> Hi, >> >> >> On 12/12/2017 11:25 AM, Rafael J. Wysocki wrote: >>> > > [cut] (trimming list) > >>>>> >>>>> >>>>> >>>>> What about converting this to using struct fwnode instead of adding >>>>> fields to it? >>>> >>>> >>>> >>>> I didn't really want to add another field here, but I've also pointed out >>>> how I thought converting it to a fwnode wasn't a good choice. >>>> >>>> https://lkml.org/lkml/2017/11/20/502 >>>> >>>> Mostly because IMHO its even more misleading (lacking any >>>> fwnode_operations) >>>> than misusing the of_node as a void *. >>> >>> >>> I'm not sure what you mean. >> >> >> Converting the DT drivers/cacheinfo.c code to use a fwnode_handle is >> straightforward. But IMHO it doesn't solve the readability problem of either >> casting the ACPI/PPTT token directly to the resulting fwnode_handle *, or >> alternatively an actual fwnode_handle with bogus fwnode_operations to wrap >> that token. > > I'm not talking about that at all. > >>> >>> Anyway, the idea is to have one pointer in there instead of two that >>> cannot be used at the same time and there's no reason why of_node >>> should be special. >> >> >> Avoid two pointers for size, or readability? Because the last >> version had a union with of_node, which isn't strictly necessary as I can >> just cast the pptt token to of_node. There is exactly one line of code after >> that which uses the token and it doesn't care about type. > > So call this field "token" or similar. Don't call it "of_node" and > don't introduce another "firmware_node" thing in addition to that. > That just is a mess, sorry. I sort of agree, I think I can just change the whole of_node to a generic 'void *firmware_unique' which works fine for the PPTT code, it should also work for the DT code in cache_leaves_are_shared(). The slight gocha is there is a bit of DT code which initially runs earlier that uses of_node as an indirect parameter to a couple functions (by just passing the cacheinfo). Let me see if I can tweak that a bit. Frankly, If I understood completely all the *priv cases I suspect it might be possible to collapse *of_node into that as well. That is as long as no one decides to flush out DT on x86, or PPTT on x86.