From: Chris Wilson chris@chris-wilson.co.uk
commit d3de5616d36462a646f5b360ba82d3b09ff668eb upstream.
After applying an engine reset, on some platforms like Jasperlake, we occasionally detect that the engine state is not cleared until shortly after the resume. As we try to resume the engine with volatile internal state, the first request fails with a spurious CS event (it looks like it reports a lite-restore to the hung context, instead of the expected idle->active context switch).
Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: stable@vger.kernel.org Cc: Mika Kuoppala mika.kuoppala@linux.intel.com Signed-off-by: Andi Shyti andi.shyti@linux.intel.com Reviewed-by: Gwan-gyeong Mun gwan-gyeong.mun@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20221212161338.1007659-1-andi.... (cherry picked from commit 3db9d590557da3aa2c952f2fecd3e9b703dad790) Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/i915/gt/intel_reset.c | 34 ++++++++++++++++++++++++++++------ 1 file changed, 28 insertions(+), 6 deletions(-)
--- a/drivers/gpu/drm/i915/gt/intel_reset.c +++ b/drivers/gpu/drm/i915/gt/intel_reset.c @@ -278,6 +278,7 @@ out: static int gen6_hw_domain_reset(struct intel_gt *gt, u32 hw_domain_mask) { struct intel_uncore *uncore = gt->uncore; + int loops = 2; int err;
/* @@ -285,18 +286,39 @@ static int gen6_hw_domain_reset(struct i * for fifo space for the write or forcewake the chip for * the read */ - intel_uncore_write_fw(uncore, GEN6_GDRST, hw_domain_mask); + do { + intel_uncore_write_fw(uncore, GEN6_GDRST, hw_domain_mask);
- /* Wait for the device to ack the reset requests */ - err = __intel_wait_for_register_fw(uncore, - GEN6_GDRST, hw_domain_mask, 0, - 500, 0, - NULL); + /* + * Wait for the device to ack the reset requests. + * + * On some platforms, e.g. Jasperlake, we see that the + * engine register state is not cleared until shortly after + * GDRST reports completion, causing a failure as we try + * to immediately resume while the internal state is still + * in flux. If we immediately repeat the reset, the second + * reset appears to serialise with the first, and since + * it is a no-op, the registers should retain their reset + * value. However, there is still a concern that upon + * leaving the second reset, the internal engine state + * is still in flux and not ready for resuming. + */ + err = __intel_wait_for_register_fw(uncore, GEN6_GDRST, + hw_domain_mask, 0, + 2000, 0, + NULL); + } while (err == 0 && --loops); if (err) GT_TRACE(gt, "Wait for 0x%08x engines reset failed\n", hw_domain_mask);
+ /* + * As we have observed that the engine state is still volatile + * after GDRST is acked, impose a small delay to let everything settle. + */ + udelay(50); + return err; }