From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 09EB62853E9 for ; Fri, 16 Jan 2026 19:32:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768591925; cv=none; b=fPi1Al+3xsZW5C5Tqz+QtmHnwWPfY0PLbGyuyWwFwUd/IZHMpQYN9iHk7Oy5ocLVlrxq7hcv/Ooj+XSv4M0QDsMeINWVtU+hLQQqRl4op8sSVVUVoLa0rBRt2h7Iou1VdxpdWKNRS5he7sDmKAuN0lucyat3OJYjBh2m4736O8M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768591925; c=relaxed/simple; bh=WjlXhjzehPTRTBKfaodANcY5xdbA/Ttgspw7hyyPaVw=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=k/1gbEJmgIKb6EI7LcnT2wCC4N05opy8A6PzYd2i4k4nW6TTIpC9FgO1R/HzDil2TehmHuO1DtLBlYQUDpDUTGfde+5Ii+FhFe/uUsbkSn0IGA51hrgxUNIYRSLAdMowukyERjK69HCXlEVDMFTeCvd0/Frb+3Md0vQhAeHSOW4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WdHLFqpJ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="WdHLFqpJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 638C3C116C6; Fri, 16 Jan 2026 19:32:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768591924; bh=WjlXhjzehPTRTBKfaodANcY5xdbA/Ttgspw7hyyPaVw=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=WdHLFqpJa1u+KlcpY1Nr/RjOJh32opiPqECZBUECO8OtUp40Aqq7fKFs40O2eX1YO EivP8njCidU9DC3Om5DPxnN6bGQgOxrQqn7cas/gA3EYimVc52FYzHMco+ydpqIYG+ RavFpieT5f2LoS36o8+AVVuNJ1UJmsWXhHksOBTyMulFwDpv6A/Cpj/DiUCD+hlesX ZmStJH6Osdt4KxiN2azedSDetz2axX9Nbf7eo/nFglqjPMzEuX25S2MxU16yRMk3ba M5Qn+NY9PA4yxYatIaYxEIjOAQutULj1i1VRGOd0nFdQprxDP4mEX2KMiQxanqbOtc artWay5Q3WBeA== Date: Fri, 16 Jan 2026 13:32:03 -0600 From: Bjorn Helgaas To: fengchengwen Cc: linux-pci@vger.kernel.org, Wei , Eric.VanTassell@amd.com, bhelgaas@google.com, jonathan.cameron@huawei.com, wangzhou1@hisilicon.com, wanghuiqiang@huawei.com, liuyonglong@huawei.com Subject: Re: RFC about how to obtain PCIE TPH steer-tag on ARM64 platform Message-ID: <20260116193203.GA959102@bhelgaas> Precedence: bulk X-Mailing-List: linux-pci@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: On Fri, Jan 16, 2026 at 08:21:30AM +0800, fengchengwen wrote: > On 1/15/2026 1:03 AM, Bjorn Helgaas wrote: > > On Wed, Jan 14, 2026 at 11:39:27AM +0800, fengchengwen wrote: > >> On 1/14/2026 3:07 AM, Bjorn Helgaas wrote: > >>> On Mon, Jan 12, 2026 at 11:01:31AM +0800, fengchengwen wrote: > >>>> Hi all, > >>>> > >>>> We want to enable PCIE TPH feature on ARM64 platform, but we encounter the > >>>> following problem: > >>>> > >>>> 1. The pcie_tph_get_cpu_st() function invokes the ACPI DSM method to > >>>> obtain the steer-tag of the CPU. According to the definition of > >>>> the DSM method [1], the cpu_uid should be "ACPI processor uid". > >>> > >>>> 2. In the current implementation, the ACPI DSM method is invoked > >>>> directly using the logical core number, which works on the x86 > >>>> platform but does not work on the ARM64 platform because the > >>>> logical core ID is not the same as the ACPI processor ID when the > >>>> PG exists. > >>> > >>> PG? > >> > >> partial good > > > > I still don't know what "partial good" means :) Is that something > > from a spec? > > Because of some issues (like manufacturing variances), certain circuits > (e.g., some cores) might not work normally. For these cases, we can use > the part at a reduced specification, which is the PG mentioned here. Ah, got it :) If you go this direction, maybe you can expand that part of the commit log a bit, since I don't think "PG" or "partial good" is a widely-known term.