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 X-Spam-Level: X-Spam-Status: No, score=-0.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 14C79C31E5B for ; Tue, 18 Jun 2019 16:50:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DB4292084B for ; Tue, 18 Jun 2019 16:50:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="OYFrrnNY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730005AbfFRQuJ (ORCPT ); Tue, 18 Jun 2019 12:50:09 -0400 Received: from mail-wr1-f68.google.com ([209.85.221.68]:38482 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729859AbfFRQuJ (ORCPT ); Tue, 18 Jun 2019 12:50:09 -0400 Received: by mail-wr1-f68.google.com with SMTP id d18so279697wrs.5 for ; Tue, 18 Jun 2019 09:50:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=KSk4moREDVQrfaFvvaG4JNEpQO7UXRGLSRSH/qJ+Hf8=; b=OYFrrnNYl9Boz+yv/ZqqkPtI+ZZCBmg3QVTr6t3T7Tujvs9N+iWArZa1sXtsu63+mK yF1DPTBjzZTRCzoD6Ng5l8CBQ/jVwvhnuKdcCOfiAlVISTjPT2aid54erklkFX368Obz E/86CpYRNLVyC7leuks6PBrNF/rrcZgs36GhhxRhcJHEmsnJKmBmjwbZnlP20WMd7dmn vduei46eD42DJo5XxEPTdNvHtFvcYuLtRx54fnXx9a856TaMQhBtweQT7f9JW4mjvcip mW9QIxEKmzROPOIzXTzmbVy2yQ2kVHktkRihmDSf8GUtbJ8gn9bA8zF/+aUnA15U2Uhs OLWg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=KSk4moREDVQrfaFvvaG4JNEpQO7UXRGLSRSH/qJ+Hf8=; b=pQKWasvsHuIx/fQzCIgWfFQvMQC75aQggSoLPVomPfZesegrtJhH6JUt8D1hL5x/c/ qk93UjL9tV9bEedn5D6ifkfQfELhZeLEHdImHINo9lZE19TPhBYmfg4VpMgARCwfepbu He7al5s+1H2eWpIFsg68svcqtlpuxQkqlr1AzGfJs7FnKNAKiye/HvL8NWUuZWvEeB/F gejUNMW6SATPiqIfl3YxAKFFcYRCdpDBvCxEiRU63gI+CAqKrpplW0GecW5TGCoget1K 9DW78bwWJ3HaO/zFBV+hAAatW8o/LX++YqTFc/UN71MCT9TeAZfNuW+jaaxZHJ4BfsSW +DuA== X-Gm-Message-State: APjAAAWWyAj6XS7lyUw9zJDwFTPGvzP+HNiCc3WpHH+ee23NXpNmqVkK 3V6Q7rz/M28Tn+y/UJuzDBMDhQ== X-Google-Smtp-Source: APXvYqz02pp7jrNPiLtRBNsaULwRQxJ/0Ckr/N049AUpbNenDnGGjDoaGajTn9C+jKdSxnVaUXHD7Q== X-Received: by 2002:adf:e6c6:: with SMTP id y6mr20234263wrm.191.1560876607432; Tue, 18 Jun 2019 09:50:07 -0700 (PDT) Received: from [192.168.86.34] (cpc89974-aztw32-2-0-cust43.18-1.cable.virginm.net. [86.30.250.44]) by smtp.googlemail.com with ESMTPSA id l8sm41152736wrg.40.2019.06.18.09.50.06 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 18 Jun 2019 09:50:06 -0700 (PDT) Subject: Re: [PATCH] dmaengine: qcom-bam: fix circular buffer handling To: Sricharan R , vkoul@kernel.org Cc: dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org References: <20190614142012.31384-1-srinivas.kandagatla@linaro.org> <2d370a33-fa16-45ca-cf82-9d775349f806@codeaurora.org> <544851f6-58b8-2506-01ce-5c4d1f93fb3c@linaro.org> From: Srinivas Kandagatla Message-ID: <31574ef2-d675-bb36-08d1-18b756ebd29e@linaro.org> Date: Tue, 18 Jun 2019 17:50:06 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org On 18/06/2019 17:27, Sricharan R wrote: > The Macro's expect that buffer size is power of 2. So we are infact passing the actual correct > size ( MAX_DESCRIPTORS + 1 = 4096) This will make the circular buffer macros happy but question is that do we actually have that many descriptor buffers? This is what is in the driver: #define BAM_DESC_FIFO_SIZE SZ_32K #define MAX_DESCRIPTORS (BAM_DESC_FIFO_SIZE / sizeof(struct bam_desc_hw) - 1) #define BAM_FIFO_SIZE (SZ_32K - 8) Wouldn't having MAX_DESCRIPTORS + 1 = 4096 lead to overflow the actual descriptor memory size of (SZ_32K - 8) ? --srini