On Wed, May 31, 2023 at 12:25:10PM +0800, Sui Jingfeng wrote: > On 2023/5/31 04:11, Bjorn Helgaas wrote: > > On Tue, May 30, 2023 at 06:16:55PM +0800, Sui Jingfeng wrote: > > > As some arch(m68k for example) doesn't have config_pci enabled, drivers[1] > > > call pci_clear_master() without config_pci guard can not built. > > > > > > drivers/gpu/drm/etnaviv/etnaviv_pci_drv.c: > > > In function 'etnaviv_gpu_pci_fini': > > > > > drivers/gpu/drm/etnaviv/etnaviv_pci_drv.c:32:9: > > > error: implicit declaration of function 'pci_clear_master'; > > > did you mean 'pci_set_master'? [-Werror=implicit-function-declaration] > > > 32 | pci_clear_master(pdev); > > > | ^~~~~~~~~~~~~~~~ > > > | pci_set_master > > > cc1: some warnings being treated as errors > > > > > > [1] https://patchwork.freedesktop.org/patch/539977/?series=118522&rev=1 > > I don't mind adding a stub if it's needed, but I don't understand why > > it's needed here. > > For a single driver that supports both platform devices and PCI devices, > > Sometimes there is no way to separate the PCI driver part and the platform > driver part cleanly and clearly. > > For example, the module_init() and module_exit() functions, > > where we have to register PCI drivers and platform drivers there. > > We can't simply let the entire driver depend on PCI in Kconfig, > > This will make this driver unable to compile, which it's originally could. > > The PCI core could do such a thing for us, and > > There is no need to introduce a driver-specific guard then. > > > There is already a dummy stub for pci_set_master(). > > Therefore, pci_clear_master() should also have a counterpart. > > They should emerge in pairs. > > This could probably eliminate pain for PCI driver writers, > > This patch is still useful. > > > > The caller is in etnaviv_pci_drv.c, and if I > > understand the patch at [1], etnaviv_pci_drv.c is only compiled when > > CONFIG_PCI=y. > > Yes, you are right. This is the right thing to do for the driver, though. > > Pure PCI device driver does not need to worry about this. > > Like drm/ast, drm/amdgpu, drm/radeon, etc. > > But drm/etnaviv is special; it's a platform driver that could pass the > compile test originally. > > > When patching it (Etnaviv) with PCI device driver support, > > This forces the PCI driver writer to add another config option. > > (which depends on the PCI config option.) in the Kconfig. > > For my case, it's theDRM_ETNAVIV_PCI_DRIVER config option. So if I understand correctly, you would prefer not to add the DRM_ETNAVIV_PCI_DRIVER config option, and if we add this stub, you won't need to add it? That's a good reason to add this patch. Bjorn
