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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1E548C433FE for ; Tue, 8 Nov 2022 08:35:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230154AbiKHIfR (ORCPT ); Tue, 8 Nov 2022 03:35:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46004 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233633AbiKHIfO (ORCPT ); Tue, 8 Nov 2022 03:35:14 -0500 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3FA2A1145B for ; Tue, 8 Nov 2022 00:35:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1667896510; x=1699432510; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=lKJrzjG+bRmj1VC2Tjh8tPVeg76t7p98tJy0l6m3AG8=; b=Wfrx8dFhsnEzNBCJR8LxRSB5cEtwB2PZkJfRWODKmYfri6cXV7V8N2QY KpxvWuc2i+06H1PJybhUa4TtNhJfgNRGpaEe6yi4ePd+qjjd8VwwmBUS2 P3ydViYbQ7PZYhsTvshMYICzATWtBXPPsQF2KhsRX3FHHo6HsN9NEw2/O 5WXOqzpjE5b7ESwUCmqyMYHoXWyHswdL47JnR/yJNCPYGgU/nAVh8fo7G JsT0JTP/ErDyi7MC+O9qItup6yRuKhkduV1i+wBg1WMBRvpc+tM59mKRF dYIPLsfXKZsxZFXwYSoqGHUzjcGV1A4GhmaPIcgaDs4bNPpXL0wOyd63I Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10524"; a="294010783" X-IronPort-AV: E=Sophos;i="5.96,147,1665471600"; d="scan'208";a="294010783" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Nov 2022 00:35:05 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10524"; a="587295788" X-IronPort-AV: E=Sophos;i="5.96,147,1665471600"; d="scan'208";a="587295788" Received: from ahunter6-mobl1.ger.corp.intel.com (HELO [10.0.2.15]) ([10.252.56.164]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Nov 2022 00:35:04 -0800 Message-ID: <38161cf2-4e6e-dbb3-4743-a21657b92451@intel.com> Date: Tue, 8 Nov 2022 10:34:59 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Firefox/102.0 Thunderbird/102.4.2 Subject: Re: Question about EMMC CMDQ HOST CONTROLLER INTERFACE (CQHCI) DRIVER Content-Language: en-US To: Shawn Lin , =?UTF-8?B?SnlhbiBDaG91IFvlkajoirflrold?= Cc: linux-mmc References: <5842d536cb0d4086a225ea0fa2d42e72@realtek.com> <0f8f0d91-9e1f-c71e-86a6-25a6bdb4f6b1@rock-chips.com> From: Adrian Hunter Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki In-Reply-To: <0f8f0d91-9e1f-c71e-86a6-25a6bdb4f6b1@rock-chips.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-mmc@vger.kernel.org On 8/11/22 10:28, Shawn Lin wrote: > On 2022/11/8 16:20, Adrian Hunter wrote: >> On 8/11/22 09:25, Jyan Chou [周芷安] wrote: >>> Hello Adrian Hunter, >>> >>> We are now using the upstream code of EMMC CMDQ HOST CONTROLLER INTERFACE (CQHCI) DRIVER, but we found that the existing driver cannot support the limitation of Synopsys IP. >>> >>> Synopsys IP has a description on their data book " While using DMA, the host memory data buffer size and start address must not exceed 128 MB". > > Synopsys-based SDHCI IP does have a limitation of 128MB boundary. But it > has already been solved by upstream driver. > > FYI: > > commit b85c997d2cfefe7d1f706b85ae46e35a50e3131c ("mmc: sdhci-of-dwcmshc: solve 128MB DMA boundary limitation") CQHCI has its own DMA descriptors, so maybe a similar change is needed for CQHCI? > >>> >>> I am wondering whether there is a method or patch that can fix this boundary limitation. >>> Thanks. >>> Best Regards, >>> Jyan Chou >> >> Hello Jyan Chou >> >> I am not clear on what the exact limitation is.  The driver never uses buffers as big as 128 MB. >> To restrict DMA to low memory addresses a DMA mask can be used. >> >> But perhaps you mean not to cross a 128 MB boundary? >> >> Please cc your questions to the linux kernel mmc mailing list: linux-mmc@vger.kernel.org because others >> can answer too. >> >> Regards >> Adrian