On 20/04/2022 00:04, Robin Murphy wrote:
On 2022-04-19 14:04, Dmitry Baryshkov wrote:
This reverts commit e2a88eabb02410267519b838fb9b79f5206769be. The commit
in question makes msm_use_mmu() check whether the DRM 'component master'
device is translated by the IOMMU. At this moment it is the 'mdss'
device.
However on platforms using the MDP5 driver (e.g. MSM8916/APQ8016,
MSM8996/APQ8096) it's the mdp5 device, which has the iommus property
(and thus is "translated by the IOMMU"). This results in these devices
being broken with the following lines in the dmesg.
[drm] Initialized msm 1.9.0 20130625 for 1a00000.mdss on minor 0
msm 1a00000.mdss: [drm:adreno_request_fw] loaded qcom/a300_pm4.fw from
new location
msm 1a00000.mdss: [drm:adreno_request_fw] loaded qcom/a300_pfp.fw from
new location
msm 1a00000.mdss: [drm:get_pages] *ERROR* could not get pages: -28
msm 1a00000.mdss: could not allocate stolen bo
msm 1a00000.mdss: [drm:get_pages] *ERROR* could not get pages: -28
msm 1a00000.mdss: [drm:msm_alloc_stolen_fb] *ERROR* failed to allocate
buffer object
msm 1a00000.mdss: [drm:msm_fbdev_create] *ERROR* failed to allocate fb
Getting the mdp5 device pointer from this function is not that easy at
this moment. Thus this patch is reverted till the MDSS rework [1] lands.
It will make the mdp5/dpu1 device component master and the check will be
legit.
[1] https://patchwork.freedesktop.org/series/98525/
Oh, DRM...
If that series is going to land got 5.19, could you please implement the
correct equivalent of this patch within it?
Yes, that's the plan. I'm sending a reworked version of your patch
shortly (but it still depends on [1]).
I'm fine with the revert for now if this patch doesn't work properly in
all cases, but I have very little sympathy left for DRM drivers riding
roughshod over all the standard driver model abstractions because
they're "special". iommu_present() *needs* to go away, so if it's left
to me to have a second go at fixing this driver next cycle, you're
liable to get some abomination based on of_find_compatible_node() or
similar, and I'll probably be demanding an ack to take it through the
IOMMU tree ;)
No need for such measures :-)
Thanks,
Robin.
Fixes: e2a88eabb024 ("drm/msm: Stop using iommu_present()")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
---
drivers/gpu/drm/msm/msm_drv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/msm/msm_drv.c
b/drivers/gpu/drm/msm/msm_drv.c
index b6702b0fafcb..e2b5307b2360 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -263,7 +263,7 @@ bool msm_use_mmu(struct drm_device *dev)
struct msm_drm_private *priv = dev->dev_private;
/* a2xx comes with its own MMU */
- return priv->is_a2xx || device_iommu_mapped(dev->dev);
+ return priv->is_a2xx || iommu_present(&platform_bus_type);
}
static int msm_init_vram(struct drm_device *dev)
--
With best wishes
Dmitry
