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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 54F6EC43465 for ; Mon, 21 Sep 2020 15:13:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 28A102075E for ; Mon, 21 Sep 2020 15:13:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727777AbgIUPNc (ORCPT ); Mon, 21 Sep 2020 11:13:32 -0400 Received: from mga05.intel.com ([192.55.52.43]:50719 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726413AbgIUPNc (ORCPT ); Mon, 21 Sep 2020 11:13:32 -0400 IronPort-SDR: g9rUCueUgy7STz7p2BuVjiNPkYlSahn6Y+5PotgS2qKpj30MvauUMj7yR/6lkvtCDUy89YFdRq sqwr/pmzO+8A== X-IronPort-AV: E=McAfee;i="6000,8403,9751"; a="245236770" X-IronPort-AV: E=Sophos;i="5.77,286,1596524400"; d="scan'208";a="245236770" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Sep 2020 08:13:29 -0700 IronPort-SDR: evHvP/WUYitjOm2oxlHWZO9ukc8IkQ1fE6TM22CEVZcIVVcUxjr1i4LXOFpfQ4xzqzU21jv6W2 xbgI46sYyhfg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.77,286,1596524400"; d="scan'208";a="346587140" Received: from linux.intel.com ([10.54.29.200]) by FMSMGA003.fm.intel.com with ESMTP; 21 Sep 2020 08:13:27 -0700 Received: from [10.215.245.98] (mreddy3x-MOBL.gar.corp.intel.com [10.215.245.98]) by linux.intel.com (Postfix) with ESMTP id 26DF358058B; Mon, 21 Sep 2020 08:13:23 -0700 (PDT) Subject: Re: [PATCH v6 2/2] Add Intel LGM soc DMA support. To: Andy Shevchenko Cc: dmaengine@vger.kernel.org, vkoul@kernel.org, devicetree@vger.kernel.org, robh+dt@kernel.org, linux-kernel@vger.kernel.org, chuanhua.lei@linux.intel.com, cheol.yong.kim@intel.com, qi-ming.wu@intel.com, malliamireddy009@gmail.com, peter.ujfalusi@ti.com References: <748370a51af0ab768e542f1537d1aa3aeefebe8a.1599605765.git.mallikarjunax.reddy@linux.intel.com> <20200909111424.GQ1891694@smile.fi.intel.com> <36a42016-3260-3933-bbf9-9203c4124115@linux.intel.com> <20200918122029.GX3956970@smile.fi.intel.com> From: "Reddy, MallikarjunaX" Message-ID: Date: Mon, 21 Sep 2020 23:13:22 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20200918122029.GX3956970@smile.fi.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Andy, Thanks for your comments. My comments are in line. On 9/18/2020 8:20 PM, Andy Shevchenko wrote: > On Fri, Sep 18, 2020 at 11:42:54AM +0800, Reddy, MallikarjunaX wrote: >> On 9/9/2020 7:14 PM, Andy Shevchenko wrote: >>> On Wed, Sep 09, 2020 at 07:07:34AM +0800, Amireddy Mallikarjuna reddy wrote: > ... > >>>> + help >>>> + Enable support for intel Lightning Mountain SOC DMA controllers. >>>> + These controllers provide DMA capabilities for a variety of on-chip >>>> + devices such as SSC, HSNAND and GSWIP. >>> And how module will be called? >>  are you expecting to include 'default y' ? > I'm expecting to see something like "if you choose M the module will be called > bla-foo-bar." Look at the existing examples in the kernel. ok, i will change bool to tristate. > > ... > >>>> +ldma_update_bits(struct ldma_dev *d, u32 mask, u32 val, u32 ofs) >>>> +{ >>>> + u32 old_val, new_val; >>>> + >>>> + old_val = readl(d->base + ofs); >>>> + new_val = (old_val & ~mask) | (val & mask); >>> With bitfield.h you will have this as u32_replace_bits(). >> -  new_val = (old_val & ~mask) | (val & mask); >> + new_val = old_val; >> + u32_replace_bits(new_val, val, mask); >> >> I think in this function we cant use this because of compilation issues >> thrown by bitfield.h . Expecting 2nd and 3rd arguments as constant numbers >> not as type variables. >> >> ex: >> u32_replace_bits(val, 0, IPA_REG_ENDP_ROUTER_HASH_MSK_ALL); > How comes these are constants? In the above you have a function which does > r-m-w approach to the register. It should be something like > > old = read(); > new = u32_replace_bits(old, ...); > write(new); > >> ./include/linux/bitfield.h:131:3: error: call to '__field_overflow' declared >> with attribute error: value doesn't fit into mask >>    __field_overflow();     \ >>    ^~~~~~~~~~~~~~~~~~ >> >> ./include/linux/bitfield.h:119:3: error: call to '__bad_mask' declared with >> attribute error: bad bitfield mask >>    __bad_mask(); >>    ^~~~~~~~~~~~ > So, even with constants u32_replace_bits() must work. Maybe you didn't get how? Thanks Andy, now i know how u32_replace_bits() is working. The mask is not the continuous bits in some cases. Due to the mask bits are not continuous u32_replace_bits() can't be used here. Ex:         u32 mask = DMA_CPOLL_EN | DMA_CPOLL_CNT; Comes to __field_overflow error, update bits in the 'val' are aligned with mask bits. Because of the this reason in u32_replace_bits() 'val'  exceeds the 'mask' in some cases which is causing __field_overflow error. >>>> + if (new_val != old_val) >>>> + writel(new_val, d->base + ofs); >>>> +} > ... > >>>> + /* High 4 bits */ >>> Why only 4? >> this is higher 4 bits of 36 bit addressing.. > Make it clear in the comment. ok. > > ... > >>>> +device_initcall(intel_ldma_init); >>> Each _initcall() in general should be explained. >> ok. is it fine? >> >> /* Perform this driver as device_initcall to make sure initialization >> happens >>  * before its dma clients of some are platform specific. make sure to >> provice >>  * registered dma channels and dma capabilities to client before their >>  * initialization. >>  */ > /* > * Just follow proper multi-line comment style. > * And use dma -> DMA. > */ Ok.