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 7BA9B4F30C4 for ; Wed, 30 Sep 2026 14:52:11 +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=1790779938; cv=none; b=Myu2CHOcAMwLXsdDRV0k1RZMAlzdL8uQmtaUb4betcbxHmO//KPW+RGUmzzvbrWaWV2N9ihKYPTDnOGnp6WoVVAnf16JrqMOfVxM7rE6YLbDcIK7pOfzsa1LsBgQGCS5URPgnyTvhpBBt1Pr3rB1CRWCrUWUOSYKjNLHLI3BD8g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790779938; c=relaxed/simple; bh=tpyo+2UwzI5VmJ2rPxg7mG5onH4fcLyStorD3/5bCuQ=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=A74vYq0rahK4fMkptT36MwmCOotqo7aYU4L+JTQkhQh46Y/Z2kErhr7FDvE+dYBYNgI121H6goPbMFgndOiJwALOEyp76pfM+e4gSL/S3rdsTiMwACTSLn9stzYlMEy2ELPDbUFMGkrtFi9T+CEMCa+1vlAIqqmjw2jF5ek0XJE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=m5a3TU5x; 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="m5a3TU5x" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E6B61F000FF; Wed, 30 Sep 2026 14:52:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790779926; bh=tpyo+2UwzI5VmJ2rPxg7mG5onH4fcLyStorD3/5bCuQ=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=m5a3TU5xno638hRmwot9vSP4cFP+Rj+ShiNnzZUTuZdP6w3YzcNxSbj1YHEbMWLsb cPyIlwI32ujLMKju6lj4vxEt2CWGEWuWBViBlney0J41LbT0ivSpe8wfJ00UpW/ILs Q4C4mgDUOYiXBXVhXATSHJUefedwR9ZG/0ffJjUVavdLU8f830hXWayQ+bHOMMwhvf Qddv4tqUXq5NCvLlbIoP4yLXO3UUV6GL07ODdn/ITnJTmBLFLWmK1aJGVLo/aom9H9 6VhLPgLc1e9Bgg91ApLduHiS2qrQyKMEodaK2cTah8QUJJPn+r+kF5LOjTi7KBRfkA oxsMg4LNlYL3w== From: sashiko-bot@kernel.org Subject: Re: [PATCH 1/2] PCI: Write RCB only when it changes Reply-To: sashiko-reviews@lists.linux.dev To: "Stefan Roese" Cc: linux-pci@vger.kernel.org In-Reply-To: <20260930144650.3701516-2-stefan.roese@mailbox.org> References: <20260930144650.3701516-1-stefan.roese@mailbox.org> <20260930144650.3701516-2-stefan.roese@mailbox.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 30 Sep 2026 14:52:05 +0000 Message-Id: <20260930145206.4E6B61F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: > pci_configure_rcb() does a read-modify-write of the Link Control > register of every endpoint at enumeration, even when RCB already has > the right value. Some devices react to any write of this register. >=20 > The Renesas uPD720201 xHCI (1912:0014) comes out of reset with ASPM L0s > and L1 enabled in Link Control. On a link whose Root Port supports no > ASPM, nothing else writes that register before the driver loads, and > the chip clears ASPM Control itself during the firmware download. After > a host write, even of the unchanged value 0x0003, it no longer does > so. ASPM stays enabled, and the first access to the xHCI BAR runs into > PCIe completion timeouts that hang the system. >=20 > Seen on an AMD Versal board (CPM Root Port without ASPM support): the > hang bisects to this commit, reverting it fixes it, and on a kernel > without it a single setpci write of the unchanged value reproduces it. >=20 > Read Link Control first and write it only when RCB has to change. >=20 > Fixes: 1a6845aaa6de ("PCI: Initialize RCB from pci_configure_device()") > Cc: stable@vger.kernel.org > Assisted-by: Claude:claude-opus-5-5 > Signed-off-by: Stefan Roese Sashiko has reviewed this patch and found no issues. It looks great! --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260930144650.3701= 516-1-stefan.roese@mailbox.org?part=3D1