Re: [PATCH v4 0/5] powervr: MT8173 GPU support

Hi Chen-Yu,

A follow-up on the GX6250 issue.

I ran the diagnostic test I mentioned in my previous reply, and I now
have a reproducible system hang along with HWRT/free-list lifetime
traces.

I built a diagnostic kernel with temporary tracing around the PowerVR
HWRT and free-list lifetime paths, and ran:

PVR_I_WANT_A_BROKEN_VULKAN_DRIVER=1 glmark2-es2-drm

The test was run from multi-user.target with no display manager running.

This time glmark2 progressed past the point where it had previously
failed, but later the entire system became unresponsive during the
desktop/blur part of the benchmark.

At that point:

- SSH stopped responding
- local keyboard and VT switching stopped responding
- the system required a hard power cycle

The HWRT teardown trace immediately before the hang was interesting.

Normal HWRT destruction repeatedly looked like this:

dataset-release
-> HWRTDATA cleanup data=1, err=0
-> HWRTDATA cleanup data=0, err=0
-> free-list release slot=0
-> free-list release slot=1

For the last HWRT visible before the machine stopped responding, the
trace ended at:

pvr-hwrt: dataset-release hwrt=ffff0000c0c62800 ...
pvr-hwrt: cleanup hwrt=ffff0000c0c62800 data=1 err=0 ...
pvr-hwrt: cleanup hwrt=ffff0000c0c62800 data=0 err=0 ...

There was no further PowerVR trace before the system hung.

Therefore, I do not think I can conclude that the free-list reference
counting itself is the root cause.

What I can say from this instrumentation is that both HWRTDATA cleanup
calls returned successfully, and the trace stopped before
hwrt_fini_kernel_structure() reached its first free-list release
message.

The tracing is intentionally verbose and may affect timing, so I do
not want to over-interpret the exact failure point.

I have the diagnostic patch, the full kernel log, the HWRT/free-list
lifetime trace, and the glmark2 output available.

Would it be useful for me to send these to the Imagination/DRM mailing
lists now, or is there a particular person or list you would prefer me
to report this to?

If there are specific additional tracepoints you would like around
hwrt_data_fini_fw_structure() or hwrt_fini_common_fw_structure(), I
can build another diagnostic kernel and reproduce the issue again.

Thanks again for taking a look.

Best regards,
YoungJoon Lee

2026年7月30日(木) 21:38 Chen-Yu Tsai <[email protected]>:
>
> On Thu, Jul 30, 2026 at 7:06 PM Brian Masney <[email protected]> wrote:
> >
> > Hi Angelo and Chen-Yu,
> >
> > On Thu, Jul 30, 2026 at 10:23:14AM +0200, AngeloGioacchino Del Regno wrote:
> > > On 7/30/26 06:51, Chen-Yu Tsai wrote:
> > > > On Tue, Jul 28, 2026 at 10:33 PM AngeloGioacchino Del Regno
> > > > <[email protected]> wrote:
> > > > >
> > > > > On 7/28/26 15:13, Chen-Yu Tsai wrote:
> > > > > > On Tue, Jul 28, 2026 at 9:10 PM Brian Masney <[email protected]> wrote:
> > > > > > > On Tue, Jul 28, 2026 at 05:17:58PM +0800, Chen-Yu Tsai wrote:
> > > > > > > > Hi everyone,
> > > > > > > >
> > > > > > > > This is v4 of my MT8173 PowerVR GPU support series.
> > > > > > > >
> > > > > > > > This time around Mesa was ready for basic testing, using both vulkanmark
> > > > > > > > and glmark2-es2-drm (with Zink). Details below.
> > > > > > > >
> > > > > > > > Changes since v3 (all in the clk driver patch):
> > > > > > > > - Changed pm_runtime_put() to pm_runtime_put_sync()
> > > > > > > > - Added missing of_node_put() in remove function
> > > > > > > >
> > > > > > > > Changes since v2 (all in the clk driver patch):
> > > > > > > > - Made COMMON_CLK_MT8173_MFGTOP depend on PM
> > > > > > > >     - Needed since the driver implements PM domains using the generic PM
> > > > > > > >       domain library, which also depends on PM
> > > > > > > >     - Fixes build breakage (kernel test robot)
> > > > > > > > - Fixed "RST_DELAY_CNT" name (Brian)
> > > > > > > > - Dropped unused mfg_desc (Brian)
> > > > > > > > - Added check of clk_prepare_enable()'s return value in
> > > > > > > >     clk_mt8173_mfgtop_power_on() (Brian)
> > > > > > > > - Saved error value for return in IS_ERR(data->clk_26m) branch
> > > > > > > >     (Dan Carpenter / kernel test robot w/ smatch)
> > > > > > > >
> > > > > > > > Changes since v1:
> > > > > > > > - Adapted to changed DT bindings
> > > > > > > > - Dropped driver change
> > > > > > > > - Use same power domain for "a" and "b" GPU power domains
> > > > > > > >
> > > > > > > >
> > > > > > > > This series enables the PowerVR GPU found in the MT8173 SoC, found in
> > > > > > > > some Chromebooks.
> > > > > > >
> > > > > > > I'm making a pull for Stephen for the clk changes. Should patches 1,2,4
> > > > > > > go through the clk tree? Patches 3,5 go through the DRM tree?
> > > > > >
> > > > > > Only patches 1 and 2 should go through the clock tree.
> > > > > >
> > > > > > Patch 3, 4, 5 can all go through the soc tree if Angelo wants to pick up
> > > > > > DT binding patches. Otherwise I can push patch 3 through drm-misc.
> > > > > >
> > > > >
> > > > > Not sure if I can really take the DRM bindings patch through soc.
> > > > >
> > > > > I will take the devicetree ones exactly right now, even though it's going to
> > > > > give warnings.
> > > >
> > > > Apologies for missing this, but the first DT patch depends on the clk DT
> > > > bindings patch for the clk ID macros. This is causing build errors in
> > > > linux-next right now.
> > > >
> > > > Not sure how we can fix this right now.
> > > >
> > > > Brian, would it be possible for you to split out that patch into a
> > > > separate immutable branch for Angelo to merge?
> >
> > Yes, I can split things out and make an immutable branch this morning.
> > But it sounds too late for that.
> >
> > > >
> > > > Otherwise Angelo might need to drop the DT patches until the next cycle.
> > >
> > > Yeah, that's so bad.
> > > I'd be happy to be able to resolve this, but it's too late on my side.
> > >
> > > I should've checked the DT patches more carefully, my bad: I got a bit too excited
> > > to finally see this PowerVR stuff working on MT8173 and going upstream.
> > >
> > > Sadly, I have to drop the devicetree patches :-(
> >
> > Chen-Yu: Could Angelo add an Acked-by to the three patches, and then I send
> > Stephen an additional pull with just those patches? Do you think he'd
> > pull that?
>
> (replying from my @kernel.org address again because I don't feel like
>  pulling out my work laptop.)
>
> I think the question is whether the soc & dt maintainers would be bothered
> by it or not.
>
> No need to sweat over it though. It's not like the GPU driver is production
> ready anyway. We can just merge the DT patches in the next cycle. :)
>
>
> ChenYu