Re: [PATCH] gpu: host1x: Free the IOMMU domain when there is no device to attach

From: Mikko Perttunen
Date: Tue Jul 11 2017 - 13:10:25 EST

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
case when the device-tree does not contain the proper iommu node,
best to keep going without IOMMU support rather than failing.
This allows the driver to probe and function instead of taking
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@xxxxxxxxxxxx
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
return -ENOMEM;
err = iommu_attach_device(host->domain, &pdev-

- 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
host->iova_end = geometry->aperture_end;
err = host1x_channel_list_init(host);
if (err) {
dev_err(&pdev->dev, "failed to initialize channel

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@xxxxxxxxxxx>
Tested-on: Apalis TK1, Apalis T30, Beaver, Colibri T30, Jetson-TK1

Finally graphics working again, thanks guys!

Yay! :)