On 2022-04-19 22:08, Dmitry Baryshkov wrote:
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 :-)
Awesome, thanks!
Robin.
