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 67B6219D074 for ; Sun, 14 Jun 2026 02:31:40 +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=1781404301; cv=none; b=EQrdm00OFsAxN55dTlIfxFl6YN57PcHneZFgMGBrnjnM/F7EqdTQ3o5LatAqY7e6jE6hNHgUsN3aHsVk22NBwnQcdgzm2Jtajo9+RAcUrKdxGfYO3wqo3aYdzLXK80Cq/eHPztFAx4DG2gQ2o3W8YJa7zHly6PlQTuaAQ2crZFE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781404301; c=relaxed/simple; bh=yOw20AfG2+pooGtXtuJFspV/3rZPgd5XBJgt1m2qhr0=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=XMPWA9MptjGpXufoDP4/bCr5AKMz2FVD7zwTK6fB+G0arN1kNWiWhQnmeQ8PzQuXid6oAnjTkTCXozd4doH0eRMFB4RJcuxxkxGwLozJJdUjvS9QyylpzKNtf98hfvWyy/YgkLwCBJaq8nuhFcudKuXMAWXlKvbFZTriMHkzMtc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dtHZKELW; 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="dtHZKELW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A51F41F000E9; Sun, 14 Jun 2026 02:31:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781404299; bh=yOw20AfG2+pooGtXtuJFspV/3rZPgd5XBJgt1m2qhr0=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=dtHZKELWGFvnhDX4uxjhuge0h+yEmZEOv9b3qOVGUUqMatY/Omtt5J3tj+EddjS4U I3xlcMjDkzX/li0rRKL5NzL2jqX+IIQ3ydIcnNxcztUXSNQFST/30iI06c36c9HwUk 23tWfO+LWwkFepdCv2TEE+IcVWUyoLcXdzgUkJP0Tw+iubB7+Ee0OSpOr8rAa+Ikwe gI3vDzZ8s2qOfdD3JfNLBysavb+bTQCRyngyVoLBKWkWKZcYTvwBYMUEVpsapSUJjh CbnJLfZuWm+ZWvuGU2ApBLxExl11cbUWbXWIk1JB6tweD580nEkFfsJBWWotuaE+BA HkiCRgLchkmug== From: sashiko-bot@kernel.org Subject: Re: [PATCH] PCI: meson: Fix PERST# timing by asserting reset before LTSSM enable Reply-To: sashiko-reviews@lists.linux.dev To: "Gowtham Kudupudi" Cc: neil.armstrong@linaro.org, linux-amlogic@lists.infradead.org, linux-pci@vger.kernel.org In-Reply-To: <20260614015620.20432-1-gowtham@ferryfair.com> References: <20260614015620.20432-1-gowtham@ferryfair.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Sun, 14 Jun 2026 02:31:39 +0000 Message-Id: <20260614023139.A51F41F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: > On warm reboot, the PCIe controller's LTSSM starts link training > immediately if PERST# is already deasserted from the previous boot. > The driver then pulses PERST# for only 500us, which is too short to > properly reset the endpoint device that has already started training. >=20 > Fix by moving the PERST# assert/deassert pulse BEFORE enabling LTSSM, > so the endpoint gets a clean reset cycle before link training begins. >=20 > This was found on Amlogic G12B (A311D) with NVMe on an M.2 slot. > Cold boot worked because POR held PERST# low; warm reboot did not. > The fix was confirmed on a Banana Pi CM4 with Waveshare IO base board. >=20 > Signed-off-by: Gowtham Kudupudi Sashiko has reviewed this patch and found no issues. It looks great! --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260614015620.2043= 2-1-gowtham@ferryfair.com?part=3D1