From patchwork Tue Jan 9 14:42:21 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: PCI: dwc: fix enumeration end when reaching root subordinate From: Koen Vandeputte X-Patchwork-Id: 10152443 Message-Id: <1515508941-20055-1-git-send-email-koen.vandeputte@ncentric.com> To: linux-pci@vger.kernel.org Cc: bhelgaas@google.com, lorenzo.pieralisi@arm.com, Joao.Pinto@synopsys.com, jingoohan1@gmail.com, niklas.cassel@axis.com, Koen Vandeputte , Mika Westerberg Date: Tue, 9 Jan 2018 15:42:21 +0100 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 to remain undetected, as these would be connected to bus 0x02 or higher. Fix this by initializing the RC to a subordinate value of 0xff, meaning that all busses [0x00-0xff] are reachable through this RC. Fixes: a20c7f36bd3d ("PCI: Do not allocate more buses than available in parent") Signed-off-by: Koen Vandeputte Tested-by: Niklas Cassel Cc: Mika Westerberg --- Will send separate patches to stable as this file got moved/renamed 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 */