From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 3CF2FB7103 for ; Tue, 16 Nov 2010 02:17:12 +1100 (EST) Subject: Re: [PATCH v2] fsldma: add support to 36-bit physical address Mime-Version: 1.0 (Apple Message framework v1081) Content-Type: text/plain; charset=us-ascii From: Kumar Gala In-Reply-To: Date: Mon, 15 Nov 2010 09:16:57 -0600 Message-Id: <3B38AD35-39A2-4A54-8109-65D6DE436227@kernel.crashing.org> References: <1289477789-10651-1-git-send-email-leoli@freescale.com> <54AAF9B7-9533-45B8-9C49-A964203AF707@kernel.crashing.org> To: Timur Tabi Cc: dan.j.williams@intel.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Nov 13, 2010, at 4:43 PM, Timur Tabi wrote: > On Thu, Nov 11, 2010 at 5:56 AM, Kumar Gala = wrote: >=20 >> Is there any reason we shouldn't set DMA_BIT_MASK(64) since the DMA = block programming model allows the address to be 64-bits? >=20 > Can you explain that? The DMA registers only have room for 36 bits > for the physical address. The programming model (if you look at the free-space in the registers = and data structures) supports a 64-bit address. I'm trying to avoid = changing the driver in the future if we have >36-bit. However this is = such a minor worry that I'll stop and just ack the patch as is. - k=