Re: [PATCH] drm/msm: Revert "drm/msm: Stop using iommu_present()"

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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.



[Index of Archives]     [Linux DRI Users]     [Linux Intel Graphics]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]
  Powered by Linux