> -----Original Message----- > From: Andrey Smirnov [mailto:andrew.smirnov@xxxxxxxxx] > Sent: 2018年12月8日 7:57 > To: niklas.cassel@xxxxxxxxxx > Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>; linux-pci@xxxxxxxxxxxxxxx; Bjorn > Helgaas <bhelgaas@xxxxxxxxxx>; Chris Healy <cphealy@xxxxxxxxx>; > Leonard Crestez <leonard.crestez@xxxxxxx>; Aisheng Dong > <aisheng.dong@xxxxxxx>; Richard Zhu <hongxing.zhu@xxxxxxx>; > dl-linux-imx <linux-imx@xxxxxxx>; linux-arm-kernel > <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; linux-kernel > <linux-kernel@xxxxxxxxxxxxxxx> > Subject: Re: [PATCH] PCI: controller: dwc: Make PCI_IMX6 depend on > PCIEPORTBUS > > On Fri, Dec 7, 2018 at 5:11 AM Niklas Cassel <niklas.cassel@xxxxxxxxxx> > wrote: > > > > On Thu, Dec 06, 2018 at 08:55:13PM -0800, Andrey Smirnov wrote: > > > On Thu, Dec 6, 2018 at 2:28 AM Lucas Stach <l.stach@xxxxxxxxxxxxxx> > wrote: > > > > > > > > Am Mittwoch, den 05.12.2018, 23:45 -0800 schrieb Andrey Smirnov: > > > > > Building a kernel with CONFIG_PCI_IMX6=y, but > > > > > CONFIG_PCIEPORTBUS=n produces a system where built-in PCIE > > > > > bridge (16c3:abcd) isn't bound to pcieport driver. This, in > > > > > turn, results in a PCIE bus that is capable of enumerating > > > > > attached PCIE device, but lacks functional interrupt support. > > > > > > > > This is odd. AFAIK PCI port services are a totally optional thing > > > > and them being absent should not lead to a non-functional PCI bus. > > > > So I would really like to see some deeper analysis what is going on here. > > > > > > > > > > AFAICT, this is due to pcieport driver enabling MSI of the bridge > > > device (16c3:abcd) via pcie_port_device_register() -> > > > pcie_init_service_irqs() -> pcie_port_enable_irq_vec() -> etc. > > > > > > I did an experiment on a i.MX8MQ/PCIE -> i210 setup I have: I > > > disabled CONFIG_PCIEPORTBUS and hacked igb_main.c enough to make > the > > > i210 driver believe it should fall back onto legacy interrupts. Even > > > without pcieport present in the system, i210 worked as expected via > > > legacy interrupts, which seems to collaborate my conjecture above. > > > > > > Thanks, > > > Andrey Smirnov > > > > IIUC PCIEPORTBUS should not be needed for MSIs to work, it is only > > needed if you want e.g. PME or AER. > > > > The difference is that if PCIEPORTBUS is enabled, a MSI irq vector > > will be allocated for the Root Complex itself, so that it can send an > > irq when e.g. AER has detected an error. > > > > > > If we disregard that MSI handling is currently broken on DWC PCIe: > > > https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmar > > > c.info%2F%3Fl%3Dlinux-pci%26m%3D154214986924244%26w%3D2&d > ata=02%7C > > > 01%7Chongxing.zhu%40nxp.com%7Cd0e75c24b7504c3f395508d65c9fc1a3% > 7C686ea > > > 1d3bc2b4c6fa92cd99c5c301635%7C0%7C1%7C636798238552985486& > sdata=rwd > > edF0SijZqkFrpSHFq7uLmXeftGag0pJyT9XC4NOc%3D&reserved=0 > > It is very possible to have MSIs on dragonboard 820c, which also uses > > the DWC PCIe controller, without having PCIEPORTBUS selected: > > > > # zcat /proc/config.gz | grep -E "PCIE_QCOM|PCIEPORTBUS" > > # CONFIG_PCIEPORTBUS is not set > > CONFIG_PCIE_QCOM=y > > > > > > # lspci -v -s 0000:00:00.0 > > 0000:00:00.0 PCI bridge: Qualcomm Device 0104 (prog-if 00 [Normal > decode]) > > ... > > Capabilities: [50] MSI: Enable- Count=1/32 Maskable+ 64bit+ > > > > # lspci -v -s 0000:01:00.0 > > 0000:01:00.0 Network controller: Qualcomm Atheros QCA6174 802.11ac > Wireless Network Adapter (rev 32) > > ... > > Capabilities: [50] MSI: Enable+ Count=1/8 Maskable+ 64bit- > > > > > > # cat /proc/interrupts | grep MSI > > 70: 5620 0 0 0 PCI-MSI > 524288 Edge ath10k_pci > > > > So perhaps this is a bug specific to imx6? > > > > Yeah, that seems entirely plausible. I reached out to NXP via one of the > support channels to clarify. I'll report if I hear back from them. > [Richard Zhu] Did some tests. The MSI_EN of the MSI CAP of RC should be set to 1 on iMX6 PCIe. Otherwise, the MSI wouldn't be triggered although the device is present and the MSIs are assigned. > Thanks, > Andrey Smirnov
