Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752827AbdLLXlN (ORCPT ); Tue, 12 Dec 2017 18:41:13 -0500 Received: from mail-oi0-f66.google.com ([209.85.218.66]:40376 "EHLO mail-oi0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752723AbdLLXlJ (ORCPT ); Tue, 12 Dec 2017 18:41:09 -0500 X-Google-Smtp-Source: ACJfBosbSTysFEhrvHjVCDkndp922/EqjCMwlu7ozSYC8JOiSm+PGUk2/g7/oGZifxze5TvdyUWljAMw6THcK8+dEtA= MIME-Version: 1.0 In-Reply-To: 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: "Rafael J. Wysocki" Date: Wed, 13 Dec 2017 00:41:07 +0100 X-Google-Sender-Auth: eJ2csC_V70ziWS3o8_TMYgj7oFU Message-ID: Subject: Re: [PATCH v5 4/9] drivers: base cacheinfo: Add support for ACPI based firmware tables To: Jeremy Linton Cc: "Rafael J. Wysocki" , "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 Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2720 Lines: 91 On Wed, Dec 13, 2017 at 12:37 AM, Jeremy Linton wrote: > 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. I'm not aware of any plans to go in that direction. Anyway, that would be a worry of whoever wanted to do that. No need to worry about it upfront.