From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Wed, 14 Oct 2015 11:36:04 +0200 Subject: [PATCH v9 3/6] pci:host: Add Altera PCIe host controller driver In-Reply-To: References: <1444790492-4051-1-git-send-email-lftan@altera.com> <5088538.zEUtS0EC0S@wuerfel> Message-ID: <5210459.PtmhWaT6RM@wuerfel> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wednesday 14 October 2015 17:28:45 Ley Foon Tan wrote: > On Wed, Oct 14, 2015 at 5:09 PM, Arnd Bergmann wrote: > > On Wednesday 14 October 2015 16:32:25 Ley Foon Tan wrote: > >> On Wed, Oct 14, 2015 at 4:20 PM, Arnd Bergmann wrote: > >> > On Wednesday 14 October 2015 10:41:29 Ley Foon Tan wrote: > >> >> +static int altera_pcie_remove(struct platform_device *pdev) > >> >> +{ > >> >> + struct altera_pcie *pcie = platform_get_drvdata(pdev); > >> >> + > >> >> + altera_pcie_free_irq_domain(pcie); > >> >> + platform_set_drvdata(pdev, NULL); > >> >> + return 0; > >> >> +} > >> > > >> > I just noticed this. Does it actually work to unload the module > >> > and tear down all the pci_dev structures in a safe way? > >> Good catch. It only can be compiled as builtin-moduley now, so we can > >> remove this _remove callback function. > > > > I think we should change both: make it possible to load the > > driver dynamically, and remove the altera_pcie_remove function. > This driver depends on the pci fixups to work correctly. But, fixups > callback functions in this driver are not being call if the driver is > loadable module. Ah, I see. We should find a better way to deal with this, as we are getting an increasing number of host driver specific fixups. Bjorn, do you have any idea here? Could we perhaps have a helper function that lets us register fixups dynamically? > The linker script keeps all pci fixup callbacks in pci fixup regions > during kernel compile time. So, it needs to be builtin module. Do you > know any way we can update those fixup regions? The only method I'm aware of at the moment is move the fixups to drivers/pci/quirks.c and enclose them in an #ifdef if you want them to not appear in kernels that don't support your SoC. > > You can prevent the module from being unloaded if you also remove > > the module_platform_driver() directive and add a module_init() > > without a matching module_exit(). > > > > Please also add a '.suppress_bind_attrs = true,' flag in the driver > > struct to prevent manual unbinding. > I think we don't need these if it only can work as builtin module. No, this is orthogonal, you need it either way, as built-in drivers can still be unbound by writing to sysfs. Try writing the device name to /sys/bus/platform/drivers/altera-pcie/unbind and watch it blow up ;-) Arnd