From fc110ebdd014dd1368c98e7685b47789c31fab42 Mon Sep 17 00:00:00 2001 From: Koen Vandeputte Date: Wed, 7 Mar 2018 10:46:39 -0600 Subject: [PATCH] PCI: dwc: Fix enumeration end when reaching root subordinate 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 Tested-by: Fabio Estevam Tested-by: Sebastian Reichel Signed-off-by: Koen Vandeputte Signed-off-by: Lorenzo Pieralisi Signed-off-by: Bjorn Helgaas Reviewed-by: Mika Westerberg Acked-by: Lucas Stach Cc: stable@vger.kernel.org # v4.15+ Cc: Binghui Wang Cc: Jesper Nilsson Cc: Jianguo Sun Cc: Jingoo Han Cc: Kishon Vijay Abraham I Cc: Lucas Stach Cc: Mika Westerberg Cc: Minghuan Lian Cc: Mingkai Hu Cc: Murali Karicheri Cc: Pratyush Anand Cc: Richard Zhu Cc: Roy Zang Cc: Shawn Guo Cc: Stanimir Varbanov Cc: Thomas Petazzoni Cc: Xiaowei Song Cc: Zhou Wang --- drivers/pci/dwc/pcie-designware-host.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/pci/dwc/pcie-designware-host.c b/drivers/pci/dwc/pcie-designware-host.c index 8de2d5c69b1d..dc9303abda42 100644 --- a/drivers/pci/dwc/pcie-designware-host.c +++ b/drivers/pci/dwc/pcie-designware-host.c @@ -613,7 +613,7 @@ void dw_pcie_setup_rc(struct pcie_port *pp) /* 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 */ -- 2.30.2