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

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Message-ID: <10bb6bbf-b7d0-4da5-8f30-0990748493f0@arm.com>
Date: Tue, 8 Oct 2024 13:11:49 +0100
From: Robin Murphy <robin.murphy@....com>
To: Jason Gunthorpe <jgg@...dia.com>, "H. Nikolaus Schaller"
 <hns@...delico.com>
Cc: Laurent Pinchart <laurent.pinchart@...asonboard.com>,
 "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
 Christoph Hellwig <hch@....de>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Lu Baolu <baolu.lu@...ux.intel.com>, Jerry Snitselaar <jsnitsel@...hat.com>,
 Joerg Roedel <jroedel@...e.de>, tony Lindgren <tony@...mide.com>,
 Andreas Kemnade <andreas@...nade.info>,
 Linux-OMAP <linux-omap@...r.kernel.org>,
 Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
 linux-media@...r.kernel.org
Subject: Re: BUG: "iommu: Retire bus ops" breaks omap-iommu and omap3isp

On 07/10/2024 1:15 pm, Jason Gunthorpe wrote:
> 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);

Nope, just s/&pdev->dev/NULL/ here. Apologies for overlooking this.

Thanks,
Robin.

>                  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;
>          }
> 
> Jason