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Thu, 24 Sep 2026 10:14:09 +0800 (CST) X-QQ-SSF: 0000000000000000000000000000000 X-QQ-GoodBg: 0 X-BIZMAIL-ID: 5874928214263819641 EX-QQ-RecipientCnt: 18 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: multipart/signed; boundary=8f62a79aaf3f531d7ad204d4c4b9ef58a31bebd84138d89c089572e5c418; micalg=pgp-sha512; protocol="application/pgp-signature" Date: Thu, 24 Sep 2026 10:14:06 +0800 Message-Id: Cc: "Bruno Banelli" , , , , "Alex Elder" , "Yixun Lan" , "Lorenzo Pieralisi" , "Krzysztof Wilczynski" , "Rob Herring" , "Bjorn Helgaas" , "Danilo Krummrich" , "Uwe Kleine-Koenig" , "Javier Martinez Canillas" , , "linux-riscv" , "Troy Mitchell" Subject: Re: [BUG] PCI: spacemit-k1: port C probe hard-hangs a CPU with one endpoint on Milk-V Jupiter From: "Troy Mitchell" To: "Manivannan Sadhasivam" , "Encrow Thorne" X-Mailer: aerc 0.21.0-reader-ipc4 References: <20260825052249.66921-1-bbanelli@gmail.com> In-Reply-To: X-QQ-SENDSIZE: 520 Feedback-ID: esmtpsz:linux.spacemit.com:qybglogicsvrgz:qybglogicsvrgz3a-0 X-QQ-XMAILINFO: OW4JKxETGMY2ZtXC37cQOMjtmvJ65GqUQyhRbehIHzwnmoGlMeejKfbj ulQMC6wYWFuKeP5DLmRXzz6ULrJOtc/MWhr6rjSjmKy579MregMEBkbKAb4OmrefCbjSQBI xDcDgPI48wyBJej8VGW0c9l/XbZOIvkVP+uaQAFV2Qi4u4TlnNOLAjEmS1cRaSuMnohISnq kCyAKYcA6MYyl/6+xUom8XmoQaBARF0EAeEAbdiGrZXiRkCAhQMjMvhdjx3Cz2myZMih6Pj INZFCr0Bkw0CCVcyr4kWymyh733r9XcMXs+SrurY+redH8iV62UWTSurc5ejQD03oyaEqDY 9as28qi4jTlQmQjHiKL7schxs39ntwoc/67wuWVL+2Kx2Mk+lu5kP5JUDvmJrLzQDg2fOVD NzvH70RXO8jfplOc2iyFJCu7xVnoknR224BuweBi+mMRSrahE0uOz1LfqlvXlMwiv2oLLqQ rJBziovNn/EO+bqZiJmnKrV8GWHq+2s4xvcMiZ5kB+pVyTdFBQdsBKWLpsqzNbg1GBzEk+W U5NvztKZpw5MV/sQLXMxyUUu4omrkP8njO04ys/mvX0mg4f95Wo/EJKJ1OjaXdUbGekQXVe 0/KN+PbomqS00hX4EAFiIlfwe+1dkkNhk4w083R4r1iz2G457/TJf/cJWP7DakHEljhw4mh 9RjcknB2H8gDyrCWUg06p5OxoF0fTfoI4uO0CpzBzbO5jSynglYO0uBRppZmW99l79Crrej Gz7l6iMljZiK8F6Bwj8vVhoLzoTr9wsMRh0VAZEiusE5t3K+zYdkhusf4iuCLNW4jSN7sXF jBaQSQSIunhAudlEZ1qPAYJzPIHOA2pjsI8zUIjGXaKDVld2DdprWWXJibsDJ6D2ZGWPVM4 TCzvtOQHhY4+pU611HophJhseE1sI5A0aQc2Hc6Hy4ml0aJ8D093XopymMiCj2GjV5cDK7z +ZI2a5G4YbYLJg4Y3Ys5mFct8bMn6BB9jt89zQypNBYlTOkkdg6hWNE7o/7kRno6GBQ4YEK NmvBH0wzggEJur8VcyIzQgFljc22DPLfPA/xyLorBoXlC2Q5fImPmGitxl1A0FEX1cCbWF7 lGVyiV5VjDHrVsSfRKOcLT/TyC2QjjNGBwrFlsGkPilLhl58GK+W153g55XHytAZw== X-QQ-XMRINFO: NI4Ajvh11aEjEMj13RCX7UuhPEoou2bs1g== X-QQ-RECHKSPAM: 0 --8f62a79aaf3f531d7ad204d4c4b9ef58a31bebd84138d89c089572e5c418 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 On Mon Sep 21, 2026 at 4:03 PM +08, Manivannan Sadhasivam wrote: > On Mon, Sep 21, 2026 at 01:55:42PM +0800, Encrow Thorne wrote: > > [...] > >> Hi Bruno, >>=20 >> The issue was caused by a missing hardware configuration in the K1 PCIe >> initialization. >>=20 >> The PMU PCIE_CONTROL_LOGIC register contains an IGNORE_PERSTN bit (BIT(2= )). >> The hardware manual describes it as follows: >>=20 >> =E2=80=9CWhen set to 1, the PCIe controller and PHY ignore the PERSTN si= gnal from >> the link partner in both RC and EP modes.=E2=80=9D >>=20 >> This bit was not configured during RC initialization. As a result, the >> controller and PHY could still be affected by the PERSTN input during th= e >> early DBI accesses. With the Intel I225-V installed, the first DBI acces= s >> could remain pending and hang the CPU. >>=20 > > What does this 'PERSTN' bit controls? PERST# or something else? PERST# is > controlled only by the Root Complex btw. Also, why does this missing regi= ster > configuration only affecting Intel I225-V endpoint and not others? Encrow has already posted a patch here [1] and explained the reasoning; it = seems to depend on the device's behavior. Link: https://lore.kernel.org/all/20260924-spacemit-k1-pcie-fix-v1-1-002b5c= 1ba9fc@linux.spacemit.com/ [1] --=20 Troy Mitchell --8f62a79aaf3f531d7ad204d4c4b9ef58a31bebd84138d89c089572e5c418 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iIMEABYKACsWIQSL4Ay2cExaPXAQcU2YCe+A+TM0LwUCarSHbg0caUB0cm95LXku b3JnAAoJEJgJ74D5MzQvxO8A/1764CfP8OTcIm5rW5emuurOXkqTKQ7BL9ChVP5g Wre/AP9SDdlVovEUp1d9V4EYidzXJuHBOkk14Z04haPo5wMhAA== =KKPr -----END PGP SIGNATURE----- --8f62a79aaf3f531d7ad204d4c4b9ef58a31bebd84138d89c089572e5c418--