From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4A2123E958A; Thu, 28 May 2026 12:20:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779970813; cv=none; b=LxqSZxZaSGqjXAd+yGVknnN/Q/fCq52tEzn7C4s0PtgOoyqMHWAYPLTq9+zOH7nC/O1EgX4PFtyVNEjB3br87dpY+ng28H5n0XoNkpV9pohKRZxaVtpLwbItnpa3xtS7NXLr2CTJW9SuET2Sp76Br/q0PZUBbCAyR8fyylRJVT4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779970813; c=relaxed/simple; bh=/YEv4U0fe9M/TOj6z10PxlM2qsMB+GmNGkySrE/BuHY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=huGfLiJP2gljlK9nd8fMk31k/EPuXk1iLld6eIaU4PNPBdfZZBeKPNPFWuKYkt28f/KoKfT6mWb5yhEjfGG5PexEqzJus7ZpzLYadh5f0wlk2/3xlxZTvgENcUyCAPLTUe/qNhr2bQOKNr7kfiLV+o4l0z0V/AxebtCsBybQIOg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aCsyoB9S; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="aCsyoB9S" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E63DE1F000E9; Thu, 28 May 2026 12:20:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779970812; bh=S+6TYzSvlrsln1Y/UOMzT8WOi09IGDTtXp0XvWesPHI=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=aCsyoB9Sa9RuoQgBMsXUbX+hmVUriIJtE47MX08grVmKzvohqC0xFU7OjF7eWRHH3 2mFZeNO7F0KazsaovRJIkguvV6VcoEFq1W9pFrCar5SIWUiOfvPC3T9D1To5ZFMPeS 7BKzDxilObRswehzqthL08rpAn1lvoT2P2YvGZCT0jgNaNL+3QeSbXTRpGKQPY9kJV 66AZlnKtdWOlaltGSAf0gukRfN2VWXLUh8z5C2t29DVGSE91HLnHUMrz3Xd1V9sV0b rxjHhPmnPI2Kmz+NMGm+s/na3BDBHk/pBAOOtbHH0YelS6T8hRj1MZov7Szuy19qeF QVDGRNK8TwfcQ== Message-ID: Date: Thu, 28 May 2026 14:20:07 +0200 Precedence: bulk X-Mailing-List: linux-tegra@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] memory: tegra: add multi-socket support to the memory interconnect To: Thierry Reding Cc: Sumit Gupta , treding@nvidia.com, jonathanh@nvidia.com, linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org, bbasu@nvidia.com References: <20260521140546.3023819-1-sumitg@nvidia.com> <2caba07a-511e-453c-8e1e-f2b07b84a096@kernel.org> <58ae92f3-3e6d-4f60-970e-76ee4d7dbd4e@nvidia.com> <2ba14e8a-1664-48fe-ba99-c81100de78f4@kernel.org> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 28/05/2026 13:56, Thierry Reding wrote: >>>>> >>>>> - mc->debugfs.root = debugfs_create_dir("mc", NULL); >>>>> + if (!mc_debugfs_root) >>>> That's a probe path and you created a singletone. Looks like preventing >>>> async probing for no real reason. >>>> >>>> I am very against singletons and debugfs does not look like justified >>>> exception. >>> >>> The singleton was added so multi-socket MC/EMC instances could >>> share a "mc"/"emc" parent. I'll drop it in v2. >>> >>> On single-socket SoCs, the "mc"/"emc" names will be unchanged. >>> On multi-socket SoCs, each instance will create a top-level debugfs >>> dir named with dev_name(). Same pattern in tegra186-emc.c. >>> >>>   if (dev_to_node(mc->dev) == NUMA_NO_NODE) >>>       mc->debugfs.root = debugfs_create_dir("mc", NULL); >>>   else >>>       mc->debugfs.root = debugfs_create_dir(dev_name(mc->dev), NULL); >> >> You assume this is fully synced, so you as well could do a look up and >> then use what you found or create new dir. If you think that is racy, so >> is this approach... How are other drivers handling per-device debugfs >> directories? Do they also create such in the top-level? I think no. > > I think we want a top-level directory for a bit more structure in > debugfs. But I also think we want to create that top-level directory in > the module's init function rather than _probe. I was thinking about this as well but that would mean your driver will create it on every multi-arch kernel. This should be then moved to some core bus (and there are examples of that, e.g. USB), except there is no core-MC bus code to do that. > Granted, that means we > can't use any of those helper macros, but we don't use that for the MC > driver anyway. > > Thierry Best regards, Krzysztof