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=-3.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 C894EC33CB1 for ; Thu, 16 Jan 2020 10:28:36 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5532720661 for ; Thu, 16 Jan 2020 10:28:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alsa-project.org header.i=@alsa-project.org header.b="Qbuzxrfw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5532720661 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=alsa-devel-bounces@alsa-project.org Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id 7BD7C1752; Thu, 16 Jan 2020 11:27:44 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 7BD7C1752 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1579170514; bh=itRQEmYIfPlHnET/M2/mycagB8L7LLbXVvMhNk/aZiw=; h=Date:From:To:In-Reply-To:References:Cc:Subject:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=QbuzxrfwRDdLL/Ig4UTxFFcwYugC/wL9eT9PnvTzz9CpTHeqsQwsGXAr4+lwvjP8q 5p6Uj6qYy5o9BxH9ejlDychQ9CkKm4f/tyKKJkhyt4VC3H67lrPxxo84C7tHuSPlbI 1He2PxIsgr+bfml9pmeHzW7u2oVDXv3bBk4Olj+w= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id 0F0FCF8014D; Thu, 16 Jan 2020 11:27:44 +0100 (CET) Received: by alsa1.perex.cz (Postfix, from userid 50401) id CC27EF8014E; Thu, 16 Jan 2020 11:27:42 +0100 (CET) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id 4D23FF800B9 for ; Thu, 16 Jan 2020 11:27:38 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 4D23FF800B9 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 4083AADCF; Thu, 16 Jan 2020 10:27:38 +0000 (UTC) Date: Thu, 16 Jan 2020 11:27:37 +0100 Message-ID: From: Takashi Iwai To: Keyon Jie In-Reply-To: <97bbe88d1a6b63fe8e9b02bf0c5ce4a80553c48d.camel@linux.intel.com> References: <20200116045318.5498-1-yang.jie@linux.intel.com> <97bbe88d1a6b63fe8e9b02bf0c5ce4a80553c48d.camel@linux.intel.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Cc: alsa-devel@alsa-project.org Subject: Re: [alsa-devel] [PATCH] ALSA: pcm: fix buffer_bytes max constrained by preallocated bytes issue X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" On Thu, 16 Jan 2020 10:50:33 +0100, Keyon Jie wrote: > > On Thu, 2020-01-16 at 08:15 +0100, Takashi Iwai wrote: > > On Thu, 16 Jan 2020 05:53:18 +0100, > > Keyon Jie wrote: > > > With today's code, we preallocate DMA buffer for substreams at > > > pcm_new() > > > stage, and the substream->buffer_bytes_max and substream->dma_max > > > will > > > save as the actually preallocated buffer size and maximum size that > > > the > > > dma buffer can be expanded by at hw_params() state, > > > correspondingly. > > > > No, it's other way round: the former, buffer_bytes_max, is the max > > size defined by the driver (i.e. passed in snd_pcm_hardware) and the > > latter, dma_max, is the max preallocation size (passed to > > preallocation helper). > > Hi Takashi, thanks for your comment. > > First of all, have you ever hit issue I mentioned in the commit message > that we can't set buffer_bytes larger than the preallocated dma bytes? > > I found this issue in kinds of platforms, not only on SOF/SoC ones, but > also on legacy HDA ones. > > Secondly, I am not clear about the design intention of the substream- > >buffer_bytes_max and substream->dma_max, if it is as you commented > above, can you help answer my questions below inline the code? > > void snd_pcm_lib_preallocate_pages(struct snd_pcm_substream *substream, > int type, struct device *data, > size_t size, size_t max) > > static void preallocate_pages(struct snd_pcm_substream *substream, > int type, struct device *data, > size_t size, size_t max, bool managed) > { > ... > if (substream->dma_buffer.bytes > 0) > substream->buffer_bytes_max = substream- > >dma_buffer.bytes;//Keyon: this is the actual allocated buffer bytes, > what is the intention here and why it is assigned to buffer_bytes_max > which will be used to constrain on the _HW_PARAM_BUFFER_BYTES later? > > substream->dma_max = max; //Keyon: looks here it is where the > *max* param used only if we don't define SND_VERBOSE_PROCFS? what > relationship can we have with the preallocation itself? > ... > } Oh, you're right, and I completely misread the patch. Now I took a coffee and can tell you the story behind the scene. I believe the current code is intentionally limiting the size to the preallocated size. This limitation was brought for not trying to allocate a larger buffer when the buffer has been preallocated. In the past, most hardware allocated the continuous pages for a buffer and the allocation of a large buffer fails quite likely. This was the reason of the buffer preallocation. So, the driver wanted to tell the user-space the limit. If user needs to have an extra large buffer, they are supposed to fiddle with prealloc procfs (either setting zero to clear the preallocation or setting a large enough buffer beforehand). For SG-buffers, though, limitation makes less sense than continuous pages. e.g. a patch below removes the limitation for SG-buffers. But changing this would definitely cause the behavior difference, and I don't know whether it's a reasonable move -- I'm afraid that apps would start hogging too much memory if the limitation is gone. thanks, Takashi --- diff --git a/sound/core/pcm_memory.c b/sound/core/pcm_memory.c index d4702cc1d376..6a6c3469bbcd 100644 --- a/sound/core/pcm_memory.c +++ b/sound/core/pcm_memory.c @@ -96,6 +96,29 @@ void snd_pcm_lib_preallocate_free_for_all(struct snd_pcm *pcm) } EXPORT_SYMBOL(snd_pcm_lib_preallocate_free_for_all); +/* set up substream->buffer_bytes_max, which is used in hw_constraint */ +static void set_buffer_bytes_max(struct snd_pcm_substream *substream, + size_t size) +{ + substream->buffer_bytes_max = UINT_MAX; + + if (!size) + return; /* no preallocation */ + + /* for SG-buffers, no limitation is needed */ + switch (substream->dma_buffer.dev.type) { +#ifdef CONFIG_SND_DMA_SGBUF + case SNDRV_DMA_TYPE_DEV_SG: + case SNDRV_DMA_TYPE_DEV_UC_SG: +#endif + case SNDRV_DMA_TYPE_VMALLOC: + return; + } + + /* for continuous buffers, limit to the preallocated size */ + substream->buffer_bytes_max = size; +} + #ifdef CONFIG_SND_VERBOSE_PROCFS /* * read callback for prealloc proc file @@ -156,10 +179,8 @@ static void snd_pcm_lib_preallocate_proc_write(struct snd_info_entry *entry, buffer->error = -ENOMEM; return; } - substream->buffer_bytes_max = size; - } else { - substream->buffer_bytes_max = UINT_MAX; } + set_buffer_bytes_max(substream, size); if (substream->dma_buffer.area) snd_dma_free_pages(&substream->dma_buffer); substream->dma_buffer = new_dmab; @@ -206,10 +227,8 @@ static void preallocate_pages(struct snd_pcm_substream *substream, if (size > 0 && preallocate_dma && substream->number < maximum_substreams) preallocate_pcm_pages(substream, size); - - if (substream->dma_buffer.bytes > 0) - substream->buffer_bytes_max = substream->dma_buffer.bytes; substream->dma_max = max; + set_buffer_bytes_max(substream, substream->dma_buffer.bytes); if (max > 0) preallocate_info_init(substream); if (managed) _______________________________________________ Alsa-devel mailing list Alsa-devel@alsa-project.org https://mailman.alsa-project.org/mailman/listinfo/alsa-devel