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 shelob.surriel.com (shelob.surriel.com [96.67.55.147]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5CABEC74A44 for ; Tue, 14 Mar 2023 05:17:04 +0000 (UTC) Received: from localhost ([::1] helo=shelob.surriel.com) by shelob.surriel.com with esmtp (Exim 4.96) (envelope-from ) id 1pbx0C-0006su-2z; Tue, 14 Mar 2023 01:15:12 -0400 Received: from mail-qt1-x82a.google.com ([2607:f8b0:4864:20::82a]) by shelob.surriel.com with esmtps (TLS1.2) tls TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 (Exim 4.96) (envelope-from ) id 1pbx07-0006sY-0M for kernelnewbies@kernelnewbies.org; Tue, 14 Mar 2023 01:15:11 -0400 Received: by mail-qt1-x82a.google.com with SMTP id d7so15572182qtr.12 for ; Mon, 13 Mar 2023 22:15:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=vt-edu.20210112.gappssmtp.com; s=20210112; t=1678770892; h=message-id:date:content-transfer-encoding:mime-version:references :in-reply-to:subject:cc:to:from:sender:from:to:cc:subject:date :message-id:reply-to; bh=PDRQezs0OhBGXx+ieFofnSOTlmKWlOmA3Jps7UiT3Xw=; b=42DxmmRJf7Q+K/Ds3Jo0N5lc12drfOpVniph054ow60tDPcgFLyQCpNXNZhF25DBYy VQ2HOvy/G5iKl4Wmc0g5VYutDj6vp7X9wk8hObkISmvP1SvnmrffnHTCvqTtCzQjNiet nVaRUulGlY+s55AGA+jWXoAVs8oIkCK6nUiLxnr4uL8g6YnCrKF1i+x/VhQvrouV3WAN wVLBgvMNyNiMn/IudOd346DsRmvop1MNS5FItV4Jbv8NcNopGxg6i6Xlgwa+mENvyqkf qfYdzIckxL+tdaWBbxk3gCvQ3lXO2rtOycv6cc2T/81R1J2SBsX/I8wv+74TbPp28IJi U17Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678770892; h=message-id:date:content-transfer-encoding:mime-version:references :in-reply-to:subject:cc:to:from:sender:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=PDRQezs0OhBGXx+ieFofnSOTlmKWlOmA3Jps7UiT3Xw=; b=MMPd1GnBAPMT2FTLvmsleJrAa2uNrbD3biVPdhDF+mivFBrZ6clWZWUXFXlHKD5A+f LSud/yz8EbxbLpnVSYNpyPtqx9CJMWuA2gYi4a6ttSuPeuvxR9/XAEvr4zaJIncABylV 4qdkuJnQmQVkGEjQAjoICBqOOjENthTcQi7VDslYGv9irXHLPsQ00kz1+fRoyzA3ejKP ujLKahoQBO7OZdcoilwCyRKWBvU5FTD6Ks/ZaByuJEbP3SVXscMnu7vll1PkOPgDX7di x2RFBL0A6CYEnmtd0IKpRlNDf0nqggy/Kyh3Oneob0QCdDiC+8zQkEMsabi4sG1lEFyv 7F1A== X-Gm-Message-State: AO0yUKWC6BK7Zt8+LjOO05Ywj337KweiVB1MFeIQ7i0P/aDGPvH4Oeji lVnPD/BNk+/cUmiSb6cUoHOUGttrxYBKB5xgeZ0= X-Google-Smtp-Source: AK7set/ZGkA2KUoTz90AfrNUm6U1vRrRzeYAedCmrdALj37crseifuqJgS/JOf0OR9sCfB03ylJAuQ== X-Received: by 2002:ac8:5d91:0:b0:3bf:d13f:207f with SMTP id d17-20020ac85d91000000b003bfd13f207fmr30469502qtx.22.1678770891878; Mon, 13 Mar 2023 22:14:51 -0700 (PDT) Received: from turing-police ([2601:5c0:c300:1f41::adb]) by smtp.gmail.com with ESMTPSA id e28-20020a05620a015c00b007419f1561fesm1049404qkn.112.2023.03.13.22.14.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Mar 2023 22:14:50 -0700 (PDT) From: "Valdis Kl=?utf-8?Q?=c4=93?=tnieks" X-Google-Original-From: "Valdis Kl=?utf-8?Q?=c4=93?=tnieks" X-Mailer: exmh version 2.10.0-pre 07/05/2021 with nmh-1.8+dev To: "Chan Kim" Subject: Re: returned dma address value of dma_alloc_coherent, is it always in the lower 4GB range? In-Reply-To: <034901d955a7$50a377d0$f1ea6770$@etri.re.kr> References: <034901d955a7$50a377d0$f1ea6770$@etri.re.kr> Mime-Version: 1.0 Date: Tue, 14 Mar 2023 01:14:50 -0400 Message-ID: <687742.1678770890@turing-police> Cc: kernelnewbies@kernelnewbies.org X-BeenThere: kernelnewbies@kernelnewbies.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Learn about the Linux kernel List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============2474398571302576425==" Errors-To: kernelnewbies-bounces@kernelnewbies.org --===============2474398571302576425== Content-Type: multipart/signed; boundary="==_Exmh_1678770889_181321P"; micalg=pgp-sha256; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit --==_Exmh_1678770889_181321P Content-Type: text/plain; charset=us-ascii On Mon, 13 Mar 2023 21:28:28 +0900, "Chan Kim" said: > which is 32-bit addressable. Even if the device indicates (via the DMA > mask) > that it may address the upper 32-bits, consistent allocation will only > return > 32-bit addresses for DMA if the consistent DMA mask has been > explicitly changed via dma_set_coherent_mask(). This is true of the > dma_pool interface as well. > ------------------------------ > By context I guess it returns the address in lower 32bit address range even > it the coherent_dma_mask is set to some bigger value. No, you have that backwards. It's not "even if". It wil give you a 32-bit address *UNLESS* the driver has called dma_set_coherent_mask() to set a wider mask *and* the device indicates it supports more than 32 bit addresses... --==_Exmh_1678770889_181321P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Comment: Exmh version 2.9.0 11/07/2018 iQEcBAEBCAAGBQJkEALJAAoJEI0DS38y7CIciuYH/iaYM/7wHvcWqSXAUoIeGM2V 3ApHl1972qjvpLjxWnYCRcqPNQEuuRkvZnkyX64Gz/DgVn7H/2WPn4QGQGTcqtzJ RxVlWhzQJ7Z0xy5be9pzgVLsXJxQCEYsnXYAGlA4mq4L/6pBBOWy/bLt+9favUME xLalZb//RyIa+g/DjK8FGHNQJ2U7oyGQputze2XhseJd0XizhdJZ89SlzxSJjXjM VAHpW7br28JCarBNP4nMfRXe+bQsiJU1RJEBHNvojZ7qD+zHRvLnZCK+9mNLG0w2 9PRJgW/GwuunV55HSX48/18upxMbIaorwcZ06c9zqgus+QXtDGnmfyGzcxARO+Y= =Mc66 -----END PGP SIGNATURE----- --==_Exmh_1678770889_181321P-- --===============2474398571302576425== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies --===============2474398571302576425==--