PR of Maira's pmdomain/downstream/timeouts branch#7400
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pelwell merged 5 commits intoMay 27, 2026
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Consider this an Approve. |
mairacanal
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Hi @pelwell and @mairacanal, First, sorry for not getting back sooner — I've been caught up with other things and only just had the chance to test this today. Thank you both for the quick turnaround on this. The analysis of the MMU/TLB flush issue and the runtime PM work look spot-on based on what I was seeing. I've just applied the patch on my RPi4 (running headless, Debian 13): Kernel is now I'll leave it running for 48 hours and report back. Fingers crossed 🤞 Thanks again for the great work! |
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I think this is looking good enough to merge. Are you happy for me to proceed, @mairacanal? |
Commit 18605b1 ("pmdomain: bcm: bcm2835-power: Increase ASB control timeout") raised the ASB handshake polling budget from 1us to 5us. Surveying the pmdomain subsystem, 5us is still the smallest polling budget by a wide margin - comparable handshakes in other drivers use: - 100us : starfive jh71xx-pmu, apple pmgr-pwrstate - 1ms : renesas rcar-sysc, rmobile-sysc (power-on) - 10ms : renesas rcar-gen4-sysc, sunxi sun55i-pck600 - 1s : mediatek mtk-pm-domains, mtk-scpsys Raise the bcm2835 timeout to 100us, matching analogous drivers. 100us is still negligible relative to a power-domain transition and gives the V3D master ASB substantially more headroom to drain under heavy workloads, where 5us has been observed to be insufficient in practice. Cc: stable@vger.kernel.org Fixes: b826d2c ("pmdomain: bcm: bcm2835-power: Increase ASB control timeout") Signed-off-by: Maíra Canal <mcanal@igalia.com>
Make the downstream version match the upstream commit
458f2a712ab4 ("drm/v3d: Introduce Runtime Power Management").
Signed-off-by: Maíra Canal <mcanal@igalia.com>
v3d_mmu_set_page_table() ends by calling v3d_mmu_flush_all() to flush the
MMU cache and clear the TLB after reprogramming V3D_MMU_PT_PA_BASE.
v3d_mmu_flush_all() is gated by pm_runtime_get_if_active(), which returns
0 unless runtime_status == RPM_ACTIVE.
v3d_mmu_set_page_table() is called from two paths that *know* V3D is
reachable, but where the runtime PM status might be wrong:
1. v3d_power_resume(): the runtime resume callback itself, where
runtime_status is RPM_RESUMING.
2. v3d_reset(): called from the DRM scheduler timeout handler with the
hung job's pm_runtime reference held, so RPM_ACTIVE, but here we
don't need to take an extra reference for the duration of the flush
either.
In the first case pm_runtime_get_if_active() returns 0, the flush is
silently skipped, and V3D resumes executing with whatever MMUC/TLB state
happened to survive the last reset. On BCM2711, this leaves stale
translations live across runtime PM cycles, manifesting as random GPU
hangs.
Split the actual flush sequence into a helper that does the writes
unconditionally, and have v3d_mmu_set_page_table() call it directly.
Fixes: 17af1d14deaf ("drm/v3d: Introduce Runtime Power Management")
Signed-off-by: Maíra Canal <mcanal@igalia.com>
v3d_clean_caches() starts the cache-clean sequence by writing V3D_L2TCACTL_TMUWCF to V3D_CTL_L2TCACTL and then polling for that bit to clear. It does not, however, check for an L2T flush (L2TFLS) that may still be in flight from a previous operation. On pre-V3D 7.1 hardware, kicking off the TMU write-combiner flush while an L2T flush is still pending can clobber bits in L2TCACTL and cause cache inconsistencies. Poll for L2TFLS to clear before writing L2TCACTL on V3D < 7.1, ensuring any pending flush has completed before a new clean is issued. Cc: stable@vger.kernel.org Fixes: d223f98 ("drm/v3d: Add support for compute shader dispatch.") Signed-off-by: Maíra Canal <mcanal@igalia.com>
On runtime suspend, clean the V3D caches before suspending so all dirty lines are written back to memory before the power domain is shut down. Fixes several system hangs reported in [1][2][3]. Closes: raspberrypi#7381 [1] Closes: raspberrypi#7396 [2] Closes: raspberrypi#7397 [3] Fixes: 17af1d14deaf ("drm/v3d: Introduce Runtime Power Management") Signed-off-by: Maíra Canal <mcanal@igalia.com>
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@pelwell, I just rebased the branch and reviewed the patches (fixing a few nits in the commit messages), so we are good to go. Thanks! I'll proceed with the upstreaming process. |
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Turn Maira's branch into a PR to get the build artefacts.