Re: [PATCH v2 6/9] Revert "iommu/arm-smmu: Make arm-smmu-v3 explicitly non-modular"

[John Garry]

On 08/11/2019 16:47, Will Deacon wrote:
> On Fri, Nov 08, 2019 at 04:44:25PM +0000, John Garry wrote:
> > On 08/11/2019 16:17, John Garry wrote:
> > > On 08/11/2019 15:16, Will Deacon wrote:
> > > > +MODULE_DEVICE_TABLE(of, arm_smmu_of_match);
> > >
> > > Hi Will,
> > >
> > > >  Â static struct platform_driver arm_smmu_driver = {
> > > >  ÂÂÂÂÂ .driverÂÂÂ = {
> > > >  ÂÂÂÂÂÂÂÂÂ .nameÂÂÂÂÂÂÂ = "arm-smmu-v3",
> > > >  ÂÂÂÂÂÂÂÂÂ .of_match_tableÂÂÂ = of_match_ptr(arm_smmu_of_match),
> > > > -ÂÂÂÂÂÂÂ .suppress_bind_attrs = true,
> > >
> > > Does this mean that we can now manually unbind this driver from the SMMU
> > > device?
> > >
> > > Seems dangerous. Here's what happens for me:
> > >
> > > root@ubuntu:/sys# cd ./bus/platform/drivers/arm-smmu-v3
> > > ind @ubuntu:/sys/bus/platform/drivers/arm-smmu-v3# echo
> > > arm-smmu-v3.0.auto > unbind
> > > [ÂÂ 77.580351] hisi_sas_v2_hw HISI0162:01: CQE_AXI_W_ERR (0x800) found!
> > > ho [ÂÂ 78.635473] platform arm-smmu-v3.0.auto: CMD_SYNC timeout at
> > > 0x00000146 [hwprod 0x00000146, hwcons 0x00000000]
> > >
> > > >  ÂÂÂÂÂ },
> > > >  ÂÂÂÂÂ .probeÂÂÂ = arm_smmu_device_probe,
> > > > +ÂÂÂ .removeÂÂÂ = arm_smmu_device_remove,
> > > >  ÂÂÂÂÂ .shutdown = arm_smmu_device_shutdown,
> > > >  Â };
> > > > -builtin_platform_driver(arm_smmu_driver);
> > > > +module_platform_driver(arm_smmu_driver);
> > > > +
> >
> > BTW, it now looks like it was your v1 series I was testing there, on your
> > branch iommu/module. It would be helpful to update for ease of testing.

Hi Will,

> Yes, sorry about that. I'll update it now (although I'm not sure it will
> help with this -- I was going to see what happens with other devices such
> as the intel-iommu or storage controllers)

So I tried your v2 series for this - it has the same issue, as I 
anticipated.

It seems that some iommu drivers do call iommu_device_register(), so 
maybe a decent reference. Or simply stop the driver being unbound.

Cheers,
John