This is a note to let you know that I've just added the patch titled
PCI: dwc: Fix enumeration end when reaching root subordinate
to the 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: pci-dwc-fix-enumeration-end-when-reaching-root-subordinate.patch and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From fc110ebdd014dd1368c98e7685b47789c31fab42 Mon Sep 17 00:00:00 2001
From: Koen Vandeputte koen.vandeputte@ncentric.com Date: Wed, 7 Mar 2018 10:46:39 -0600 Subject: PCI: dwc: Fix enumeration end when reaching root subordinate
From: Koen Vandeputte koen.vandeputte@ncentric.com
commit fc110ebdd014dd1368c98e7685b47789c31fab42 upstream.
The subordinate value indicates the highest bus number which can be reached downstream though a certain device.
Commit a20c7f36bd3d ("PCI: Do not allocate more buses than available in parent") ensures that downstream devices cannot assign busnumbers higher than the upstream device subordinate number, which was indeed illogical.
By default, dw_pcie_setup_rc() inits the Root Complex subordinate to a value of 0x01.
Due to this combined with above commit, enumeration stops digging deeper downstream as soon as bus num 0x01 has been assigned, which is always the case for a bridge device.
This results in all devices behind a bridge bus remaining undetected, as these would be connected to bus 0x02 or higher.
Fix this by initializing the RC to a subordinate value of 0xff, which is not altering hardware behaviour in any way, but informs probing function pci_scan_bridge() later on which reads this value back from register.
The following nasty errors during boot are also fixed by this:
pci_bus 0000:02: busn_res: can not insert [bus 02-ff] under [bus 01] (conflicts with (null) [bus 01]) ... pci_bus 0000:03: [bus 03] partially hidden behind bridge 0000:01 [bus 01] ... pci_bus 0000:04: [bus 04] partially hidden behind bridge 0000:01 [bus 01] ... pci_bus 0000:05: [bus 05] partially hidden behind bridge 0000:01 [bus 01] pci_bus 0000:02: busn_res: [bus 02-ff] end is updated to 05 pci_bus 0000:02: busn_res: can not insert [bus 02-05] under [bus 01] (conflicts with (null) [bus 01]) pci_bus 0000:02: [bus 02-05] partially hidden behind bridge 0000:01 [bus 01]
Fixes: a20c7f36bd3d ("PCI: Do not allocate more buses than available in parent") Tested-by: Niklas Cassel niklas.cassel@axis.com Tested-by: Fabio Estevam fabio.estevam@nxp.com Tested-by: Sebastian Reichel sebastian.reichel@collabora.co.uk Signed-off-by: Koen Vandeputte koen.vandeputte@ncentric.com Signed-off-by: Lorenzo Pieralisi lorenzo.pieralisi@arm.com Signed-off-by: Bjorn Helgaas bhelgaas@google.com Reviewed-by: Mika Westerberg mika.westerberg@linux.intel.com Acked-by: Lucas Stach l.stach@pengutronix.de Cc: stable@vger.kernel.org # v4.15+ Cc: Binghui Wang wangbinghui@hisilicon.com Cc: Jesper Nilsson jesper.nilsson@axis.com Cc: Jianguo Sun sunjianguo1@huawei.com Cc: Jingoo Han jingoohan1@gmail.com Cc: Kishon Vijay Abraham I kishon@ti.com Cc: Lucas Stach l.stach@pengutronix.de Cc: Mika Westerberg mika.westerberg@linux.intel.com Cc: Minghuan Lian minghuan.Lian@freescale.com Cc: Mingkai Hu mingkai.hu@freescale.com Cc: Murali Karicheri m-karicheri2@ti.com Cc: Pratyush Anand pratyush.anand@gmail.com Cc: Richard Zhu hongxing.zhu@nxp.com Cc: Roy Zang tie-fei.zang@freescale.com Cc: Shawn Guo shawn.guo@linaro.org Cc: Stanimir Varbanov svarbanov@mm-sol.com Cc: Thomas Petazzoni thomas.petazzoni@free-electrons.com Cc: Xiaowei Song songxiaowei@hisilicon.com Cc: Zhou Wang wangzhou1@hisilicon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/pci/dwc/pcie-designware-host.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/pci/dwc/pcie-designware-host.c +++ b/drivers/pci/dwc/pcie-designware-host.c @@ -607,7 +607,7 @@ void dw_pcie_setup_rc(struct pcie_port * /* setup bus numbers */ val = dw_pcie_readl_dbi(pci, PCI_PRIMARY_BUS); val &= 0xff000000; - val |= 0x00010100; + val |= 0x00ff0100; dw_pcie_writel_dbi(pci, PCI_PRIMARY_BUS, val);
/* setup command register */
Patches currently in stable-queue which might be from koen.vandeputte@ncentric.com are
queue-4.15/pci-dwc-fix-enumeration-end-when-reaching-root-subordinate.patch