Re: BUG: "iommu: Retire bus ops" breaks omap-iommu and omap3isp

[H. Nikolaus Schaller]

Hi Jason,

> Am 07.10.2024 um 14:15 schrieb Jason Gunthorpe <jgg@xxxxxxxxxx>:
> 
> On Sun, Oct 06, 2024 at 09:40:00AM +0200, H. Nikolaus Schaller wrote:
>> Hi,
>> 
>> I found that the camera on our OMAP3 based system (GTA04) stopped working with v6.8-rc1.
>> There was no bug in the camera driver but the OMAP3 ISP (image signal processor) emits
>> 
>> [   14.963684] omap3isp 480bc000.isp: failed to create ARM IOMMU mapping
>> [   15.010192] omap3isp 480bc000.isp: unable to attach to IOMMU
>> [   15.023376] omap3isp 480bc000.isp: isp_xclk_set_rate: cam_xclka set to 24685714 Hz (div 7)
>> [   15.065399] omap3isp: probe of 480bc000.isp failed with error -12
>> 
>> Deeper analyses lead to this patch breaking operation. It is not fixed up to v6.12-rc1.
>> 
>> What seems to happen (in 6.8-rc1 code):
>> 
>> - omap_iommu_probe() passes &omap_iommu_ops to iommu_device_register()
>> - iommu_device_register() stores the ops in iommu->ops (only)
>> - __iommu_probe_device tries to read the ops from some fw_spec but not iommu->ops
> 
> Maybe like this?
> 
> @@ -1233,6 +1233,12 @@ static int omap_iommu_probe(struct platform_device *pdev)
>                err = iommu_device_register(&obj->iommu, &omap_iommu_ops, &pdev->dev);
>                if (err)
>                        goto out_sysfs;
> +               /*
> +                * omap has a DT reprensetation but can't use the common DT
> +                * code. Setting fwnode to NULL causes probe to be called for
> +                * every device.
> +                */
> +               obj->iommu.fwnode = NULL;
>                obj->has_iommu_driver = true;
>        }

I'll give it a try asap and report back.

BR and thanks,
Nikolaus