On Fri, 2021-08-06 at 10:41 -0700, Matt Roper wrote:
> The SFC_DONE register lives within the corresponding VD0/VD2/VD4/VD6
> forcewake domain and is not accessible if the vdbox in that domain is
> fused off and the forcewake is not initialized.
>
> This mistake went unnoticed because until recently we were using the
> wrong register offset for the SFC_DONE register; once the register
> offset was corrected, we started hitting errors like
>
> <4> [544.989065] i915 0000:cc:00.0: Uninitialized forcewake domain(s) 0x80 accessed at 0x1ce000
>
> on parts with fused-off vdbox engines.
Reviewed-by: José Roberto de Souza <jose.souza@xxxxxxxxx>
>
> Fixes: e50dbdbfd9fb ("drm/i915/tgl: Add SFC instdone to error state")
> Fixes: 82929a2140eb ("drm/i915: Correct SFC_DONE register offset")
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> Signed-off-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_gpu_error.c | 19 ++++++++++++++++++-
> 1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
> index 0f08bcfbe964..9cf6ac575de1 100644
> --- a/drivers/gpu/drm/i915/i915_gpu_error.c
> +++ b/drivers/gpu/drm/i915/i915_gpu_error.c
> @@ -727,9 +727,18 @@ static void err_print_gt(struct drm_i915_error_state_buf *m,
> if (GRAPHICS_VER(m->i915) >= 12) {
> int i;
>
> - for (i = 0; i < GEN12_SFC_DONE_MAX; i++)
> + for (i = 0; i < GEN12_SFC_DONE_MAX; i++) {
> + /*
> + * SFC_DONE resides in the VD forcewake domain, so it
> + * only exists if the corresponding VCS engine is
> + * present.
> + */
> + if (!HAS_ENGINE(gt->_gt, _VCS(i * 2)))
> + continue;
> +
> err_printf(m, " SFC_DONE[%d]: 0x%08x\n", i,
> gt->sfc_done[i]);
> + }
>
> err_printf(m, " GAM_DONE: 0x%08x\n", gt->gam_done);
> }
> @@ -1598,6 +1607,14 @@ static void gt_record_regs(struct intel_gt_coredump *gt)
>
> if (GRAPHICS_VER(i915) >= 12) {
> for (i = 0; i < GEN12_SFC_DONE_MAX; i++) {
> + /*
> + * SFC_DONE resides in the VD forcewake domain, so it
> + * only exists if the corresponding VCS engine is
> + * present.
> + */
> + if (!HAS_ENGINE(gt->_gt, _VCS(i * 2)))
> + continue;
> +
> gt->sfc_done[i] =
> intel_uncore_read(uncore, GEN12_SFC_DONE(i));
> }
