From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Fri, 19 May 2023 09:53:42 +0200 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by lore.white.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1pzuvn-006RFj-Od for lore@lore.pengutronix.de; Fri, 19 May 2023 09:53:42 +0200 Received: from bombadil.infradead.org ([2607:7c80:54:3::133]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1pzuvl-0003Mw-7h for lore@pengutronix.de; Fri, 19 May 2023 09:53:41 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=oCe4pOB9oLNhvI9nezf3I69OrJ8IsIKtWG0/gNB1994=; b=AwMm8DsT4GQkdKZdZqGtZ0G0kY DMHLdaa9ZjpaeCARR2ZVVSWa6Fg1xmkvQpMSqyNNfNJ8xyYpoTFB/k4yATq8s6n0duS+8TQhON1Sm wLcw2ns1kRGNrCHqKVfmQ8mHIfEcsGDUlU/T7tB/bhvywXxgKBtZoiYzF9Kr4roi61FtD5BYrHXaJ vnhu9aXPxckEDtdf5am4vORlE8b/AIcVJC/fxyk0HrVH6Lj5qhH47uMrJnzCGyxySHAKVCd7LgY8q /s4De3BWnnX0i+4HYH3cTkW65KFzF7WA/n07G+F9adlav1+DViOS8OP5pNesJJeuQU9ycoDAdwdnY wsWJx+qw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1pzuud-00FQTr-0j; Fri, 19 May 2023 07:52:31 +0000 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1pzuua-00FQSC-0S for barebox@lists.infradead.org; Fri, 19 May 2023 07:52:29 +0000 Received: from ptz.office.stw.pengutronix.de ([2a0a:edc0:0:900:1d::77] helo=[127.0.0.1]) by metis.ext.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1pzuuV-0003JA-2d; Fri, 19 May 2023 09:52:23 +0200 Message-ID: Date: Fri, 19 May 2023 09:52:22 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.1 Content-Language: en-US To: Sascha Hauer Cc: Barebox List References: <20230517090340.3954615-1-s.hauer@pengutronix.de> <20230517090340.3954615-32-s.hauer@pengutronix.de> <20230517143935.GB29365@pengutronix.de> <8d824d8d-91d2-e0dc-ddb5-f51b7ea9fccc@pengutronix.de> <20230519074443.GH29365@pengutronix.de> From: Ahmad Fatoum In-Reply-To: <20230519074443.GH29365@pengutronix.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230519_005228_179415_52EAF1D4 X-CRM114-Status: GOOD ( 21.25 ) X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:3::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.ext.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-5.6 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: Re: [PATCH v2 31/34] ARM: mmu32: read TTB value from register X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.ext.pengutronix.de) On 19.05.23 09:44, Sascha Hauer wrote: > On Fri, May 19, 2023 at 08:53:34AM +0200, Ahmad Fatoum wrote: >> On 17.05.23 16:39, Sascha Hauer wrote: >>> On Wed, May 17, 2023 at 03:58:01PM +0200, Ahmad Fatoum wrote: >>>> On 17.05.23 11:03, Sascha Hauer wrote: >>>>> Instead of relying on a variable for the location of the TTB which we >>>>> have to initialize in both PBL and barebox proper, just read the value >>>>> back from the hardware register. >>>> >>>> Why not initialize on first call to get_ttb()? >>> >>> get_ttb() doesn't have access to endmem which we would need to get the >>> address for the ttb. >>> >>> Also we have the value in the hardware register, why not use it? >> >> I meant initialization using the hardware register. > > You mean something like: > > static uint32_t *ttb; > > static inline uint32_t *get_ttb(void) > { > if (!ttb) > ttb = (uint32_t *)(get_ttbr() & ~0x3fff); > > return ttb; > } > > If yes, I don't know what this is good for. If no, please explain, I > don't seem to understand what you mean. That's what I mean yes (but with ttb's scope limited to get_ttb()). There are instances where get_ttb is called in a loop. Having a static variable would mimic more closely the code we have before. I see now that the Cortex-A9 TRM lists MRS cycle time as single cycle, so the static variable seems indeed unnecessary. > > Sascha > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |