From mboxrd@z Thu Jan 1 00:00:00 1970 From: Asutosh Das Subject: Query regarding ADMA descriptor allocation Date: Fri, 11 Jan 2013 18:01:27 +0530 Message-ID: <50F0061F.6070509@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from wolverine02.qualcomm.com ([199.106.114.251]:34965 "EHLO wolverine02.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753137Ab3AKMba (ORCPT ); Fri, 11 Jan 2013 07:31:30 -0500 Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: drzeus@drzeus.cx, linux-mmc@vger.kernel.org Hi In sdhci_add_host function, the number of adma descriptors allocated are 128 and each descriptor consumes 8 bytes and 1 4byte is added in the end like, kmalloc((128 * 2 + 1) * 4, GFP_KERNEL); In sdhci_adma_table_pre function, each node in sg-list is iterated and in case of a misaligned node, a descriptor is consumed, which means for a single sg-node 2 descriptors were consumed. Let's say in a situation, where there are multiple unaligned addresses in multiple sg nodes and the sg-list length is 128, wouldn't this use up all the 128 descriptors long before the entire sg-list is traversed ? -- Sent by a consultant of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.