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SubjectRe: [PATCH] gpu: host1x: Free the IOMMU domain when there is no device to attach
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On 07/11/2017 05:44 PM, Paul Kocialkowski wrote:
> On Tue, 2017-07-11 at 14:37 +0000, Marcel Ziswiler wrote:
>> On Tue, 2017-07-11 at 11:49 +0300, Paul Kocialkowski wrote:
>>> On Mon, 2017-07-10 at 21:33 +0200, Paul Kocialkowski wrote:
>>>> When there is no device to attach to the IOMMU domain, as may be
>>>> the
>>>> case when the device-tree does not contain the proper iommu node,
>>>> it
>>>> is
>>>> best to keep going without IOMMU support rather than failing.
>>>> This allows the driver to probe and function instead of taking
>>>> down
>>>> all of the tegra drm driver, leading to missing display support.
>>>
>>> Fixes: 404bfb78daf3 ("gpu: host1x: Add IOMMU support")
>>>
>>>> Signed-off-by: Paul Kocialkowski <contact-W9ppeneeCTY@public.gmane
>>>> .
>>>> org>
>>>> ---
>>>> drivers/gpu/host1x/dev.c | 8 +++++++-
>>>> 1 file changed, 7 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
>>>> index ac65f52850a6..f296738d0de8 100644
>>>> --- a/drivers/gpu/host1x/dev.c
>>>> +++ b/drivers/gpu/host1x/dev.c
>>>> @@ -186,8 +186,13 @@ static int host1x_probe(struct
>>>> platform_device
>>>> *pdev)
>>>> return -ENOMEM;
>>>>
>>>> err = iommu_attach_device(host->domain, &pdev-
>>>>> dev);
>>>>
>>>> - if (err)
>>>> + if (err == -ENODEV) {
>>>> + iommu_domain_free(host->domain);
>>>> + host->domain = NULL;
>>>> + goto iommu_skip;
>>>> + } else if (err) {
>>>> goto fail_free_domain;
>>>> + }
>>>>
>>>> geometry = &host->domain->geometry;
>>>>
>>>> @@ -198,6 +203,7 @@ static int host1x_probe(struct platform_device
>>>> *pdev)
>>>> host->iova_end = geometry->aperture_end;
>>>> }
>>>>
>>>> +iommu_skip:
>>>> err = host1x_channel_list_init(host);
>>>> if (err) {
>>>> dev_err(&pdev->dev, "failed to initialize channel
>>>> list\n");
>>
>> Please note that this does no longer cleanly apply after Mikko's 'gpu:
>> host1x: Refactor channel allocation code' commit from June 15 already
>> applied to current -next. Other than that
>
> Good to know! I intended this patch for fixing 4.12 stable, so I'm not
> even entirely sure it should land in next. The patch that fixes the
> device-tree to actually enable the iommu should be merged in priority.
>
> If that is the case and anyone wants this patch rebased to next, feel
> free to let me know and I'll send a rebased version.

We should definitely have this for non-stable kernels too - it would be
a bit strange if the driver worked if IOMMU support wasn't built into
the kernel but failed if it was :) It can also be helpful for debugging
to be able to disable IOMMU just for host1x.

>
>> Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
>> Tested-on: Apalis TK1, Apalis T30, Beaver, Colibri T30, Jetson-TK1
>>
>> Finally graphics working again, thanks guys!
>
> Yay! :)
>

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