From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 6101D269811; Wed, 12 Nov 2025 15:37:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762961880; cv=none; b=ShWHSTybVGZoHCZgCC7nmiwtfu+I1Skb3fldtIlV56UzYK1vKsSwbX5NUKI7c2gzSuSKdooMHKzAzdKF6nem7DBBd+M1DgjibDj0KG2qTdLopNBqJKfBXUR28GxkZcjuRqFp7liO7p28EVlW/WyUojdaxJ32mr44rtw75khBq20= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762961880; c=relaxed/simple; bh=ehcjdwzwHqCLwN5zy3PgTPFC6JJphL3yRBrEu05kED8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=mshUWqZ2r5qbc6RDtpjKNtkwncaz98rRxXQLXjewYWOQeKV2cf6hvpBqDGWux+uqN4cjILBTIVYs60aJZ3NThACo3n7sT7M0loITb681iXAqSiXHOQTc7i8EfZC3Zr1lSiJR3AsYY8BAKcUx9V2og0W+9cIF0Pm8+WyMLXfNfJ8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=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 17ED01515; Wed, 12 Nov 2025 07:37:50 -0800 (PST) Received: from [10.1.196.46] (e134344.arm.com [10.1.196.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2670E3F66E; Wed, 12 Nov 2025 07:37:53 -0800 (PST) Message-ID: <83ba6e8f-30be-4e82-ae1f-2443a0f16d3c@arm.com> Date: Wed, 12 Nov 2025 15:37:51 +0000 Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 10/33] arm_mpam: Add probe/remove for mpam msc driver and kbuild boiler plate To: "Shaopeng Tan (Fujitsu)" , "james.morse@arm.com" Cc: "amitsinght@marvell.com" , "baisheng.gao@unisoc.com" , "baolin.wang@linux.alibaba.com" , "bobo.shaobowang@huawei.com" , "carl@os.amperecomputing.com" , "catalin.marinas@arm.com" , "dakr@kernel.org" , "dave.martin@arm.com" , "david@redhat.com" , "dfustini@baylibre.com" , "fenghuay@nvidia.com" , "gregkh@linuxfoundation.org" , "gshan@redhat.com" , "guohanjun@huawei.com" , "jeremy.linton@arm.com" , "jonathan.cameron@huawei.com" , "kobak@nvidia.com" , "lcherian@marvell.com" , "lenb@kernel.org" , "linux-acpi@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "lpieralisi@kernel.org" , "peternewman@google.com" , "quic_jiles@quicinc.com" , "rafael@kernel.org" , "robh@kernel.org" , "rohit.mathew@arm.com" , "scott@os.amperecomputing.com" , "sdonthineni@nvidia.com" , "sudeep.holla@arm.com" , "will@kernel.org" , "xhao@linux.alibaba.com" References: <20251107123450.664001-1-ben.horgan@arm.com> <20251107123450.664001-11-ben.horgan@arm.com> From: Ben Horgan Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Shaopeng, On 11/12/25 07:22, Shaopeng Tan (Fujitsu) wrote: > Hello Ben, > >> From: James Morse >> >> Probing MPAM is convoluted. MSCs that are integrated with a CPU may only be >> accessible from those CPUs, and they may not be online. >> Touching the hardware early is pointless as MPAM can't be used until the >> system-wide common values for num_partid and num_pmg have been >> discovered. >> >> Start with driver probe/remove and mapping the MSC. >> >> CC: Carl Worth >> Tested-by: Fenghua Yu >> Tested-by: Shaopeng Tan >> Tested-by: Peter Newman >> Signed-off-by: James Morse >> Signed-off-by: Ben Horgan >> --- [...] >> +static struct mpam_msc *do_mpam_msc_drv_probe(struct platform_device >> +*pdev) { >> + int err; >> + u32 tmp; >> + struct mpam_msc *msc; >> + struct resource *msc_res; >> + struct device *dev = &pdev->dev; >> + >> + lockdep_assert_held(&mpam_list_lock); >> + >> + msc = devm_kzalloc(&pdev->dev, sizeof(*msc), GFP_KERNEL); >> + if (!msc) >> + return ERR_PTR(-ENOMEM); >> + >> + err = devm_mutex_init(dev, &msc->probe_lock); >> + if (err) >> + return ERR_PTR(err); >> + err = devm_mutex_init(dev, &msc->part_sel_lock); >> + if (err) >> + return ERR_PTR(err); >> + msc->id = pdev->id; >> + msc->pdev = pdev; >> + INIT_LIST_HEAD_RCU(&msc->all_msc_list); >> + INIT_LIST_HEAD_RCU(&msc->ris); >> + >> + err = update_msc_accessibility(msc); >> + if (err) >> + return ERR_PTR(err); > > Since the return value of update_msc_accessibility(msc) is always 0, > this check is unnecessary. Yes, I've changed update_msc_accessibility() to return void. > > Best regards, > Shaopeng TAN > Thanks, Ben