On Tue, Feb 05, 2019 at 09:27:59AM +0000, Chris Wilson wrote:
> clear_intel_crtc_state() uses the stack for saving a temporary copy of
> certain bits of the inherited crtc_state before clearing the unwanted
> bits. This pushes it over the stack limit for my little 32b Pineview,
> so move the temporary allocation to the heap instead. As we now use a
> zeroed struct, we can copy the whole extended state back to both
> preserve what bits need to be preserved and zero the rest.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_display.c | 40 +++++++++++++---------------
> 1 file changed, 18 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 636b703e02cb..6ee0cd27e875 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -11468,44 +11468,38 @@ static bool check_digital_port_conflicts(struct drm_atomic_state *state)
> return ret;
> }
>
> -static void
> +static int
> clear_intel_crtc_state(struct intel_crtc_state *crtc_state)
> {
> struct drm_i915_private *dev_priv =
> to_i915(crtc_state->base.crtc->dev);
> - struct intel_crtc_scaler_state scaler_state;
> - struct intel_dpll_hw_state dpll_hw_state;
> - struct intel_shared_dpll *shared_dpll;
> - struct intel_crtc_wm_state wm_state;
> - bool force_thru, ips_force_disable;
> + struct intel_crtc_state *saved_state;
> +
> + saved_state = kzalloc(sizeof(*saved_state), GFP_KERNEL);
> + if (!saved_state)
> + return -ENOMEM;
>
> /* FIXME: before the switch to atomic started, a new pipe_config was
> * kzalloc'd. Code that depends on any field being zero should be
> * fixed, so that the crtc_state can be safely duplicated. For now,
> * only fields that are know to not cause problems are preserved. */
>
> - scaler_state = crtc_state->scaler_state;
> - shared_dpll = crtc_state->shared_dpll;
> - dpll_hw_state = crtc_state->dpll_hw_state;
> - force_thru = crtc_state->pch_pfit.force_thru;
> - ips_force_disable = crtc_state->ips_force_disable;
> + saved_state->scaler_state = crtc_state->scaler_state;
> + saved_state->shared_dpll = crtc_state->shared_dpll;
> + saved_state->dpll_hw_state = crtc_state->dpll_hw_state;
> + saved_state->pch_pfit.force_thru = crtc_state->pch_pfit.force_thru;
> + saved_state->ips_force_disable = crtc_state->ips_force_disable;
> if (IS_G4X(dev_priv) ||
> IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
> - wm_state = crtc_state->wm;
> + saved_state->wm = crtc_state->wm;
>
> /* Keep base drm_crtc_state intact, only clear our extended struct */
> BUILD_BUG_ON(offsetof(struct intel_crtc_state, base));
> - memset(&crtc_state->base + 1, 0,
> + memcpy(&crtc_state->base + 1, &saved_state->base + 1,
> sizeof(*crtc_state) - sizeof(crtc_state->base));
>
> - crtc_state->scaler_state = scaler_state;
> - crtc_state->shared_dpll = shared_dpll;
> - crtc_state->dpll_hw_state = dpll_hw_state;
> - crtc_state->pch_pfit.force_thru = force_thru;
> - crtc_state->ips_force_disable = ips_force_disable;
> - if (IS_G4X(dev_priv) ||
> - IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
> - crtc_state->wm = wm_state;
Nice. Less risk of someone messing up the save vs. restore.
Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> + kfree(saved_state);
> + return 0;
> }
>
> static int
> @@ -11520,7 +11514,9 @@ intel_modeset_pipe_config(struct drm_crtc *crtc,
> int i;
> bool retry = true;
>
> - clear_intel_crtc_state(pipe_config);
> + ret = clear_intel_crtc_state(pipe_config);
> + if (ret)
> + return ret;
>
> pipe_config->cpu_transcoder =
> (enum transcoder) to_intel_crtc(crtc)->pipe;
> --
> 2.20.1
--
Ville Syrjälä
Intel
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