Re: [PATCH] drm/i915: Don't overwrite (e)DP PLL selection on SKL

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 15 May 2015, Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com> wrote:
> In the following commit, the place where the contents of dpll_hw_state
> in crtc_state where zeroed was changed. Prior to that commit, it
> happened when the new state was allocated, but now that happens just
> before the call the .crtc_compute_clock() hook. The DP code for SKL,
> however, sets up the (private) PLL in the encoder compute config
> function that has already run by the time that memset() is reached,
> causing the previous value to be lost.
>
> This patch fixes the issue by moving the memset() down the call chain,
> so that it is only called if the values in dpll_hw_state are going to be
> updated.
>
> commit 4978cc93d9ac240b435ce60431aef24239b4c270
> Author: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
> Date:   Tue Apr 21 17:13:21 2015 +0300
>
>     drm/i915: Preserve shared DPLL information in new pipe_config
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90462
> ---
>
> On Fri, 2015-05-15 at 13:31 +0300, Ander Conselvan De Oliveira wrote:
>> The memset() was added to fix a similar warning on a different platform,
>> but I can't remember which one now. Perhaps a more immediate fix would
>> be to move the memset() down the call chain.
>
> Like this completely untested patch.

Missing sob.

Jani.

>
> ---
>  drivers/gpu/drm/i915/intel_ddi.c     | 9 +++++++++
>  drivers/gpu/drm/i915/intel_display.c | 8 ++++++--
>  drivers/gpu/drm/i915/intel_dp.c      | 3 +++
>  3 files changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> index ec5d2ea..48d45b2 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -1087,6 +1087,9 @@ hsw_ddi_pll_select(struct intel_crtc *intel_crtc,
>  		      WRPLL_DIVIDER_REFERENCE(r2) | WRPLL_DIVIDER_FEEDBACK(n2) |
>  		      WRPLL_DIVIDER_POST(p);
>  
> +		memset(&crtc_state->dpll_hw_state, 0,
> +		       sizeof(crtc_state->dpll_hw_state));
> +
>  		crtc_state->dpll_hw_state.wrpll = val;
>  
>  		pll = intel_get_shared_dpll(intel_crtc, crtc_state);
> @@ -1309,6 +1312,9 @@ skl_ddi_pll_select(struct intel_crtc *intel_crtc,
>  	} else /* eDP */
>  		return true;
>  
> +	memset(&crtc_state->dpll_hw_state, 0,
> +	       sizeof(crtc_state->dpll_hw_state));
> +
>  	crtc_state->dpll_hw_state.ctrl1 = ctrl1;
>  	crtc_state->dpll_hw_state.cfgcr1 = cfgcr1;
>  	crtc_state->dpll_hw_state.cfgcr2 = cfgcr2;
> @@ -1419,6 +1425,9 @@ bxt_ddi_pll_select(struct intel_crtc *intel_crtc,
>  		}
>  	}
>  
> +	memset(&crtc_state->dpll_hw_state, 0,
> +	       sizeof(crtc_state->dpll_hw_state));
> +
>  	crtc_state->dpll_hw_state.ebb0 =
>  		PORT_PLL_P1(clk_div.p1) | PORT_PLL_P2(clk_div.p2);
>  	crtc_state->dpll_hw_state.pll0 = clk_div.m2_int;
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 8d40d7d..a7732b4 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -7475,6 +7475,9 @@ static int i9xx_crtc_compute_clock(struct intel_crtc *crtc,
>  	struct drm_connector_state *connector_state;
>  	int i;
>  
> +	memset(&crtc_state->dpll_hw_state, 0,
> +	       sizeof(crtc_state->dpll_hw_state));
> +
>  	for_each_connector_in_state(state, connector, connector_state, i) {
>  		if (connector_state->crtc != &crtc->base)
>  			continue;
> @@ -8516,6 +8519,9 @@ static int ironlake_crtc_compute_clock(struct intel_crtc *crtc,
>  	bool is_lvds = false;
>  	struct intel_shared_dpll *pll;
>  
> +	memset(&crtc_state->dpll_hw_state, 0,
> +	       sizeof(crtc_state->dpll_hw_state));
> +
>  	is_lvds = intel_pipe_has_type(crtc, INTEL_OUTPUT_LVDS);
>  
>  	WARN(!(HAS_PCH_IBX(dev) || HAS_PCH_CPT(dev)),
> @@ -12265,8 +12271,6 @@ static int __intel_set_mode_setup_plls(struct drm_atomic_state *state)
>  		if (needs_modeset(crtc_state)) {
>  			clear_pipes |= 1 << intel_crtc->pipe;
>  			intel_crtc_state->shared_dpll = DPLL_ID_PRIVATE;
> -			memset(&intel_crtc_state->dpll_hw_state, 0,
> -			       sizeof(intel_crtc_state->dpll_hw_state));
>  		}
>  	}
>  
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 5bd73ad..6fd9c60 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -1097,6 +1097,9 @@ skl_edp_set_pll_config(struct intel_crtc_state *pipe_config, int link_clock)
>  {
>  	u32 ctrl1;
>  
> +	memset(&pipe_config->dpll_hw_state, 0,
> +	       sizeof(pipe_config->dpll_hw_state));
> +
>  	pipe_config->ddi_pll_sel = SKL_DPLL0;
>  	pipe_config->dpll_hw_state.cfgcr1 = 0;
>  	pipe_config->dpll_hw_state.cfgcr2 = 0;
> -- 
> 2.1.0
>
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-- 
Jani Nikula, Intel Open Source Technology Center
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