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s=arc-20220608; d=hostedemail.com; t=1728910206; a=rsa-sha256; cv=none; b=EUwO8ASFtMBtkrRjkpU8xiJSpaS2tk7xhwS8Ew4/O1WVVToqJcaYx0ZwGuFbgl55dqsnZt Q1gpDHNd0jyCTNz/mKtUjEFdKiL0S3f2/940+pdsGYDEVS116e40GZAjpCUsVRF5tmPjc2 nYKemaL6U68YCLHQPXnpq+x6YgNWSyg= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf12.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 87E011007; Mon, 14 Oct 2024 05:53:11 -0700 (PDT) Received: from [10.57.86.130] (unknown [10.57.86.130]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 507043F71E; Mon, 14 Oct 2024 05:52:38 -0700 (PDT) Message-ID: <5e9ee10b-fc15-4c6a-a666-0d80ec8bdd9a@arm.com> Date: Mon, 14 Oct 2024 13:52:36 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v1 22/57] sound: Remove PAGE_SIZE compile-time constant assumption Content-Language: en-GB To: Takashi Iwai Cc: Mark Brown , Andrew Morton , Anshuman Khandual , Ard Biesheuvel , Catalin Marinas , David Hildenbrand , Greg Marsden , Ivan Ivanov , Jaroslav Kysela , Kalesh Singh , Marc Zyngier , Mark Rutland , Matthias Brugger , Miroslav Benes , Takashi Iwai , Will Deacon , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-sound@vger.kernel.org References: <20241014105514.3206191-1-ryan.roberts@arm.com> <20241014105912.3207374-1-ryan.roberts@arm.com> <20241014105912.3207374-22-ryan.roberts@arm.com> <6926988e-5532-457f-9e1a-135b03585c5d@arm.com> <8734kyyhzh.wl-tiwai@suse.de> From: Ryan Roberts In-Reply-To: <8734kyyhzh.wl-tiwai@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: D027A40007 X-Stat-Signature: egqgbp48c7h4osjfc9cfgkhz8om58fp3 X-Rspam-User: X-HE-Tag: 1728910359-71038 X-HE-Meta: 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 phpsJQri fz5aJmrLJSS/BDe8CYCziOaLqDti5v8tAXa0O1BB8JspIGWFCas6O1XpKhHncef1Tdum07ob486wkzckPILTREn3vSvY1xvA/Dn3vZLpAstjLfUqFYKl2C6ZIBJMxHCu2zXtBNuJ2nMLTKVXgFRSn3mW5f46ky/VBTqc65LA1rLqDAXEeF1f+ijabEF6EaeC/aQXu X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 14/10/2024 13:41, Takashi Iwai wrote: > On Mon, 14 Oct 2024 14:24:02 +0200, > Ryan Roberts wrote: >> >> On 14/10/2024 12:38, Mark Brown wrote: >>> On Mon, Oct 14, 2024 at 11:58:29AM +0100, Ryan Roberts wrote: >>>> -static const struct snd_pcm_hardware dummy_dma_hardware = { >>>> +static DEFINE_GLOBAL_PAGE_SIZE_VAR_CONST(struct snd_pcm_hardware, dummy_dma_hardware, { >>>> /* Random values to keep userspace happy when checking constraints */ >>>> .info = SNDRV_PCM_INFO_INTERLEAVED | >>>> SNDRV_PCM_INFO_BLOCK_TRANSFER, >>>> @@ -107,7 +107,7 @@ static const struct snd_pcm_hardware dummy_dma_hardware = { >>>> .period_bytes_max = PAGE_SIZE*2, >>>> .periods_min = 2, >>>> .periods_max = 128, >>>> -}; >>>> +}); >>> >>> It's probably better to just use PAGE_SIZE_MAX here and avoid the >>> deferred patching, like the comment says we don't particularly care what >>> the value actually is here given that it's a dummy. >> >> OK, so would that be: >> >> .buffer_bytes_max = 128*1024, >> .period_bytes_min = PAGE_SIZE_MAX, <<<<< >> .period_bytes_max = PAGE_SIZE_MAX*2, <<<<< >> .periods_min = 2, >> .periods_max = 128, >> >> ? >> >> It's not really clear to me how all the parameters interact; the buffer size >> 128K, which, if PAGE_SIZE_MAX is 64K, would hold 1 period of the maximum size. >> But periods_min is 2. So not sure that works? Or perhaps I'm trying to apply too >> much meaning to the param names... > > Right, when PAGE_SIZE_MAX is 64k, 128k won't be used because of the > constrant of periods_min=2. > > As Mark mentioned, here the actual size itself doesn't matter much. > So I suppose it'd be even simpler to define just 4096 and 4096 * 2 for > period_bytes_min and *_max instead of sticking with PAGE_SIZE. Then > it would become platform-agnostic, too. OK great I'll set these to 4096 and 4096*2 for the next version. Thanks for the feedback! > > > thanks, > > Takashi