On Wed, Oct 14, 2015 at 5:36 PM, Arnd Bergmann [off-list ref] wrote:

On Wednesday 14 October 2015 17:28:45 Ley Foon Tan wrote:

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On Wed, Oct 14, 2015 at 5:09 PM, Arnd Bergmann [off-list ref] wrote:

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On Wednesday 14 October 2015 16:32:25 Ley Foon Tan wrote:

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On Wed, Oct 14, 2015 at 4:20 PM, Arnd Bergmann [off-list ref] wrote:

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On Wednesday 14 October 2015 10:41:29 Ley Foon Tan wrote:

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+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?

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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.

By looking at the drivers/pci/quirks.c, it looks like it is mainly for
the pci endpoint devices.
Fixups for host controller are in the driver itself.

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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 ;-)

Oh I see. Will update with your suggestion.

Thanks.

Regards
Ley Foon