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 X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4280AC33CAA for ; Tue, 21 Jan 2020 05:58:23 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EDCFF22314 for ; Tue, 21 Jan 2020 05:58:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EDCFF22314 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=buserror.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 481yWd2tGczDqcn for ; Tue, 21 Jan 2020 16:58:21 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=buserror.net (client-ip=165.227.176.147; helo=baldur.buserror.net; envelope-from=oss@buserror.net; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=buserror.net Received: from baldur.buserror.net (baldur.buserror.net [165.227.176.147]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 481yTh2YVwzDqd7 for ; Tue, 21 Jan 2020 16:56:40 +1100 (AEDT) Received: from [2601:449:8480:af0:12bf:48ff:fe84:c9a0] by baldur.buserror.net with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1itmQK-0006oP-A0; Mon, 20 Jan 2020 23:50:00 -0600 Message-ID: <0948b2f469c5e9d9241477e7f0cba677bbcd1780.camel@buserror.net> From: Scott Wood To: =?UTF-8?Q?=E7=8E=8B=E6=96=87=E8=99=8E?= Date: Mon, 20 Jan 2020 23:49:59 -0600 In-Reply-To: References: Organization: Red Hat Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.1 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 2601:449:8480:af0:12bf:48ff:fe84:c9a0 X-SA-Exim-Rcpt-To: wenhu.wang@vivo.com, wenhu.pku@gmail.com, galak@kernel.crashing.org, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, trivial@kernel.org, harninder.rai@nxp.com X-SA-Exim-Mail-From: oss@buserror.net Subject: Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on baldur.buserror.net) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Rai Harninder , trivial@kernel.org, linux-kernel@vger.kernel.org, wangwenhu , Paul Mackerras , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, 2020-01-21 at 13:20 +0800, 王文虎 wrote: > From: Scott Wood > Date: 2020-01-21 11:25:25 > To: wangwenhu ,Kumar Gala , > Benjamin Herrenschmidt ,Paul Mackerras < > paulus@samba.org>,Michael Ellerman , > linuxppc-dev@lists.ozlabs.org,linux-kernel@vger.kernel.org > Cc: trivial@kernel.org,wenhu.wang@vivo.com,Rai Harninder < > harninder.rai@nxp.com> > Subject: Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM > configurable>On Mon, 2020-01-20 at 06:43 -0800, wangwenhu wrote: > > > From: wangwenhu > > > > > > When generating .config file with menuconfig on Freescale BOOKE > > > SOC, FSL_85XX_CACHE_SRAM is not configurable for the lack of > > > description in the Kconfig field, which makes it impossible > > > to support L2Cache-Sram driver. Add a description to make it > > > configurable. > > > > > > Signed-off-by: wangwenhu > > > > The intent was that drivers using the SRAM API would select the > > symbol. What > > is the use case for selecting it manually? > > > > With a repository of multiple products(meaning different defconfigs) and > multiple > developers, the Kconfigs of the Kernel Source Tree change frequently. So the > "make menuconfig" > process is needed for defconfigs' re-generating or updating for the > complexity of dependencies > between different features defined in the Kconfigs. That doesn't answer my question of how the SRAM code would be useful other than to some other driver that uses the API (which would use "select"). There is no userspace API. You could use the kernel command line to configure the SRAM but you need to get the address of it for it to be useful. > > Since this code was added almost ten years ago and there are still no (in- > > tree?) users of the API, we should just remove the sram code (unless this > > prods someone to submit such a user very soon). > > > > Yes, pretty long a time. But we DO really use the API now for > PPCE500/Freescale SoC. I do not see any users in the kernel tree. Are you talking about out-of-tree code, or something that you've submitted or will submit soon? Or are you accessing it via /dev/mem? > Like sometimes we need to reset the whole RAM, then the L2-Cache would be > used as > SRAM for backup using. Since it is useful for us now, a re-consideration is > recommanded. Where is the code that would do this? -Scott >