> -----Original Message----- > From: Arnd Bergmann [mailto:arnd@xxxxxxxx] > Sent: Wednesday, October 14, 2015 10:04 AM > To: Gabriele Paoloni > Cc: Wangzhou (B); Bjorn Helgaas; Bjorn Helgaas; jingoohan1@xxxxxxxxx; > pratyush.anand@xxxxxxxxx; linux@xxxxxxxxxxxxxxxx; > thomas.petazzoni@xxxxxxxxxxxxxxxxxx; lorenzo.pieralisi@xxxxxxx; > james.morse@xxxxxxx; Liviu.Dudau@xxxxxxx; jason@xxxxxxxxxxxxxx; > robh@xxxxxxxxxx; gabriel.fernandez@xxxxxxxxxx; > Minghuan.Lian@xxxxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; linux-arm- > kernel@xxxxxxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; zhangjukuo; qiuzhenfa; liudongdong (C); > qiujiang; xuwei (O); Liguozhu (Kenneth); Wangkefeng (Kevin); Rob > Herring > Subject: Re: [PATCH v10 4/6] PCI: hisi: Add PCIe host support for > HiSilicon SoC Hip05 > > On Wednesday 14 October 2015 08:34:43 Gabriele Paoloni wrote: > > > -----Original Message----- > > > From: Arnd Bergmann [mailto:arnd@xxxxxxxx] > > > Sent: Tuesday, October 13, 2015 12:19 PM > > > To: Gabriele Paoloni > > > Cc: Wangzhou (B); Bjorn Helgaas; Bjorn Helgaas; > jingoohan1@xxxxxxxxx; > > > pratyush.anand@xxxxxxxxx; linux@xxxxxxxxxxxxxxxx; > > > thomas.petazzoni@xxxxxxxxxxxxxxxxxx; lorenzo.pieralisi@xxxxxxx; > > > james.morse@xxxxxxx; Liviu.Dudau@xxxxxxx; jason@xxxxxxxxxxxxxx; > > > robh@xxxxxxxxxx; gabriel.fernandez@xxxxxxxxxx; > > > Minghuan.Lian@xxxxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; linux-arm- > > > kernel@xxxxxxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux- > > > kernel@xxxxxxxxxxxxxxx; zhangjukuo; qiuzhenfa; liudongdong (C); > > > qiujiang; xuwei (O); Liguozhu (Kenneth); Wangkefeng (Kevin); Rob > > > Herring > > > Subject: Re: [PATCH v10 4/6] PCI: hisi: Add PCIe host support for > > > HiSilicon SoC Hip05 > > > > > > On Tuesday 13 October 2015 06:58:42 Gabriele Paoloni wrote: > > > > > > > > > >> + > > > > > >> +static int __init hisi_pcie_init(void) > > > > > >> +{ > > > > > >> + return platform_driver_probe(&hisi_pcie_driver, > > > hisi_pcie_probe); > > > > > >> +} > > > > > >> +subsys_initcall(hisi_pcie_init); > > > > > > > > > > > > Can you use module_platform_driver() or > > > module_platform_driver_probe() > > > > > > here instead of the subsys_initcall()? No, I don't really > know > > > what > > > > > > the difference between module_platform_driver() and > > > > > > module_platform_driver_probe() is, sorry > > > > > > module_platform_driver_probe() will only call the probe function > once > > > (and fail in case of -EPROBE_DEFER), while module_platform_driver() > > > installs the platform driver in a way that the device can be bound > > > and unbound at any point. > > > > > > > > In fact, I used module_platform_driver_probe in previous > version, > > > but > > > > > A PCIe VGA card of HiSilicon will use Hip05 PCIe host, so we > > > modified > > > > > module_platform_driver_probe to subsys_initcall which will be > > > called > > > > > before module_platform_driver_probe. > > > > > > > > > > We will upstream the driver of above PCIe VGA card soon. > > > > > > I don't see a reason why a VGA driver would need the PCI host to be > > > probed this early, unless it is the only usable console in the > system. > > > > > > > Hi Bjorn, firstly many thanks for looking at this. > > > > > > > > About this last bit the reason why we use subsys_initcall() is > that > > > > our host bridge is embedded in the SoC and as such is not hot- > > > pluggable > > > > for instance see: > > > > http://lxr.free-electrons.com/source/Documentation/driver- > > > model/platform.txt#L59 > > > > > > We should still be able to build the driver as a loadable module, > > > even if you don't do that on your own kernels. > > > > Hi Arnd, I don't see the point of having loadable KOs for platform > > devices that are integrated into SoCs (like PCIe Host Controllers...) > > Mainly we want as many drivers as possible to be loadable modules, > and there is no reason why PCI needs to be different from other > subsystems here. Ok I see now. Thanks > > > > This doesn't mean that it has to be module_platform_driver, > > > subsys_initcall > > > will also work in a loadable module, it just won't be as early. > However, > > > we should try to come up with a consistent approach for all PCI > host > > > drivers, > > > I don't see any reason for hisi to be different from the others > here. > > > > To me it sounds more appropriate to adopt subsys_initcall() for all > the > > PCI Host Bridge controllers rather than having them as loadable > modules... > > > > What is your view? > > subsys_initcall() sounds odd because it's a driver rather than a > subsystem, > but I realize that most of the other levels don't fit any better. Yes well I was seeing for example the vgaarb http://lxr.free-electrons.com/source/drivers/gpu/vga/vgaarb.c#L1357 That in the init is calling pci_get_subsys() So I was wondering that the PCI devices may not be registered unless we also init the PCI host bridge through subsys_initcall()... But then maybe is the vgaarb to be buggy... > > As I said, it's not really a choice we have to make in the source code, > we can use subsys_initcall together with module_exit(), or we can > create a helper macro that is similar to module_platform_driver() > specifically for PCI that uses a particular initcall level. Ok got it. But I guess this needs to be thought and applied to all the PCI host bridge controllers... So maybe for this driver I can use module_platform_driver_probe() and then we can see... > > Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
