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 75D3314BF92; Mon, 27 Jul 2026 12:48:55 +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=1785156537; cv=none; b=nV3uyP9ZFZkXp5w8NxC2LNb0LvJiEEfKG59+k6YMbz3MRH0BOpt/MB2foGpni3xEeemRX4WpumzroDzCuwQ1EFzx3sLn2htJzoZfBRRRbT8pzbYiXrZl8JQ/mglK+QWZ4qhUJ85LqORhjUPkoSVdvS1yni5kuiakyFtrIQV8ng4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785156537; c=relaxed/simple; bh=aqREQQmKRGC8m1uoinAQ/bnhnt0KrzUoGzZaD8xIepg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=OPvA5dAQcQ86LxLBAg24JENVKq5so9QX7O+L3AHid5MclO9NEC0n5i6q2R3D9kyEENTlYzgdYHudKpyeImySYaU2a4Ffa1FyK0/1XCsCUYEZEkOoX7LqoNRtXmG+ntNxhvCFaUDBOcw88SxjuBDv3mps3Emnb5SrJvilrHNFDPs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TIXuJZnU; 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="TIXuJZnU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 648B41F00A3A; Mon, 27 Jul 2026 12:48:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785156535; bh=3idJSMzXZsFWAkGapFJSZFIUVk1ucWaPK87pZycQbG8=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=TIXuJZnUjqBGi2hczJgb3s36qAubWbk1lO5lhu0QQPlxrhviAQobavlu0GO/0vosr +6u9vSMywmZcOP1H4IKtXSNRXv6gKdmOoHQCEmo6LqG2B60mw92OUjfc9Oa8Drv8nK am1HwPhLMJOqtqaC6xFy53gxIq/kJM//t+KPyTiHQ3RvYPOAAXuZUR27l7oBtfMPHo b7s2U/oajqfFiMDJdUIyqc04laJUWwsI9Xnt+oHaHToAnH1yJTZ4kZO9L6aMIX7Uk2 wfYItDQfDUuuzJMn2SzmyoShGJPmN0x2ogD/726mpdzFuxIx8ierwyY9TyLEx2S9qX CohC6mHwSeHMQ== Date: Mon, 27 Jul 2026 14:48:47 +0200 From: Lorenzo Pieralisi To: Sudeep Holla Cc: Andre Przywara , Hanjun Guo , Catalin Marinas , Will Deacon , "Rafael J . Wysocki" , Len Brown , James Morse , Ben Horgan , Reinette Chatre , Fenghua Yu , Jonathan Cameron , Srivathsa L Rao , Ganapatrao Kulkarni , Trilok Soni , Srinivas Ramana , Niyas Sait , Lee Trager , linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 10/10] arm_mpam: detect and enable MPAM-Fb PCC support Message-ID: References: <20260723155454.1760823-1-andre.przywara@arm.com> <20260723155454.1760823-11-andre.przywara@arm.com> <20260724-finicky-knowing-foxhound-df1e56@sudeepholla> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260724-finicky-knowing-foxhound-df1e56@sudeepholla> On Fri, Jul 24, 2026 at 11:18:32AM +0100, Sudeep Holla wrote: > On Thu, Jul 23, 2026 at 05:54:54PM +0200, Andre Przywara wrote: > > The Arm MPAM-Fb specification [1] describes a protocol to access MSC > > registers through a firmware interface. This requires a shared memory > > region to hold the message, and a mailbox to trigger the access. > > For ACPI this is wrapped as a PCC channel, described using existing > > ACPI abstractions. > > > > Add code to parse those PCC table descriptions associated with an MSC, > > and store the parsed information in the MSC struct. > > There can be multiple PCC channels, and each channel can serve multiple > > MSCs, so we need to keep track of the channel usage, using a list and > > a refcount. > > This will be used by the MPAM-Fb access wrapper code. > > > > [1] https://developer.arm.com/documentation/den0144/latest > > > > Signed-off-by: Andre Przywara > > --- > > drivers/acpi/arm64/mpam.c | 6 +- > > drivers/resctrl/mpam_devices.c | 127 ++++++++++++++++++++++++++++++++- > > 2 files changed, 129 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/acpi/arm64/mpam.c b/drivers/acpi/arm64/mpam.c > > index 84963a20c3e7..ca9b8754ae5f 100644 > > --- a/drivers/acpi/arm64/mpam.c > > +++ b/drivers/acpi/arm64/mpam.c > > @@ -220,8 +220,8 @@ static struct platform_device * __init acpi_mpam_parse_msc(struct acpi_mpam_msc_ > > struct platform_device *pdev __free(platform_device_put) = > > platform_device_alloc("mpam_msc", tbl_msc->identifier); > > Looks like tbl_msc->identifier is getting stashed as pdev->id... > > > > int next_res = 0, next_prop = 0, err; > > - /* pcc, nrdy, affinity and a sentinel */ > > - struct property_entry props[4] = { 0 }; > > + /* pcc, msc-id, nrdy, affinity and a sentinel */ > > + struct property_entry props[5] = { 0 }; > > /* mmio, 2xirq, no sentinel. */ > > struct resource res[3] = { 0 }; > > struct acpi_device *companion; > > @@ -256,6 +256,8 @@ static struct platform_device * __init acpi_mpam_parse_msc(struct acpi_mpam_msc_ > > } else if (iface == MPAM_IFACE_PCC) { > > props[next_prop++] = PROPERTY_ENTRY_U32("pcc-channel", > > tbl_msc->base_address); > > + props[next_prop++] = PROPERTY_ENTRY_U32("msc-id", > > + tbl_msc->identifier); > > Why is this needed then as you can fetch it as pdev->id ? I suppose it is to have properties parity between OF and ACPI without having to change the driver property parsing path. Lorenzo