Re: [PATCH] drm/i915/icl: fix transcoder state readout

[Imre Deak <imre.deak@intel.com>]

On Tue, Dec 04, 2018 at 12:19:26PM +0200, Jani Nikula wrote:
> Commit 2ca711caeca2 ("drm/i915/icl: Consider DSI for getting transcoder
> state") clobbers the previously read TRANS_DDI_FUNC_CTL_EDP register
> contents with TRANS_DDI_FUNC_CTL_DSI0 contents. Fix the state readout,
> and handle DSI 1 while at it.
> 
> Use a bitmask for iterating and logging transcoders, because the allowed
> combinations are a bit funky.
> 
> Fixes: 2ca711caeca2 ("drm/i915/icl: Consider DSI for getting transcoder state")

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108928

> Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
> Cc: Madhav Chauhan <madhav.chauhan@intel.com>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 48 ++++++++++++++++++++----------------
>  1 file changed, 27 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index a2584f977ab1..64b0ecd538fd 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -9476,13 +9476,18 @@ static bool hsw_get_transcoder_state(struct intel_crtc *crtc,
>  	struct drm_device *dev = crtc->base.dev;
>  	struct drm_i915_private *dev_priv = to_i915(dev);
>  	enum intel_display_power_domain power_domain;
> +	unsigned long panel_transcoder_mask = BIT(TRANSCODER_EDP);
> +	unsigned long enabled_panel_transcoders = 0;
> +	enum transcoder panel_transcoder;
>  	u32 tmp;
> -	bool is_dsi = false;
> -	bool is_edp = false;
> +
> +	if (IS_ICELAKE(dev_priv))
> +		panel_transcoder_mask |=
> +			BIT(TRANSCODER_DSI_0) | BIT(TRANSCODER_DSI_1);
>  
>  	/*
>  	 * The pipe->transcoder mapping is fixed with the exception of the eDP
> -	 * transcoder handled below.
> +	 * and DSI transcoders handled below.
>  	 */
>  	pipe_config->cpu_transcoder = (enum transcoder) crtc->pipe;
>  
> @@ -9490,23 +9495,22 @@ static bool hsw_get_transcoder_state(struct intel_crtc *crtc,
>  	 * XXX: Do intel_display_power_get_if_enabled before reading this (for
>  	 * consistency and less surprising code; it's in always on power).
>  	 */
> -	tmp = I915_READ(TRANS_DDI_FUNC_CTL(TRANSCODER_EDP));
> -	if (tmp & TRANS_DDI_FUNC_ENABLE)
> -		is_edp = true;
> +	for_each_set_bit(panel_transcoder, &panel_transcoder_mask, 32) {

nit: BITS_PER_LONG or I915_MAX_TRANSCODERS?

> +		enum pipe trans_pipe;
>  
> -	if (IS_ICELAKE(dev_priv)) {
> -		tmp = I915_READ(TRANS_DDI_FUNC_CTL(TRANSCODER_DSI_0));
> -		if (tmp & TRANS_DDI_FUNC_ENABLE)
> -			is_dsi = true;
> -	}
> +		tmp = I915_READ(TRANS_DDI_FUNC_CTL(panel_transcoder));
> +		if (!(tmp & TRANS_DDI_FUNC_ENABLE))
> +			continue;
>  
> -	WARN_ON(is_edp && is_dsi);
> +		/* Log all enabled ones, only use the first one */
> +		enabled_panel_transcoders |= BIT(panel_transcoder);
> +		if (enabled_panel_transcoders != BIT(panel_transcoder))
> +			continue;


nit: As you explained for DSI dual mode both transcoders are needed and
we don't support atm two separate DSI ports. A code comment about this
would be nice. Maybe for the two DSI port case we should also warn below.

With or without the nits:
Reviewed-by: Imre Deak <imre.deak@intel.com>

>  
> -	if (is_edp || is_dsi) {
> -		enum pipe trans_pipe;
>  		switch (tmp & TRANS_DDI_EDP_INPUT_MASK) {
>  		default:
> -			WARN(1, "unknown pipe linked to edp transcoder\n");
> +			WARN(1, "unknown pipe linked to transcoder %s\n",
> +			     transcoder_name(panel_transcoder));
>  			/* fall through */
>  		case TRANS_DDI_EDP_INPUT_A_ONOFF:
>  		case TRANS_DDI_EDP_INPUT_A_ON:
> @@ -9520,14 +9524,16 @@ static bool hsw_get_transcoder_state(struct intel_crtc *crtc,
>  			break;
>  		}
>  
> -		if (trans_pipe == crtc->pipe) {
> -			if (is_edp)
> -				pipe_config->cpu_transcoder = TRANSCODER_EDP;
> -			else if (is_dsi)
> -				pipe_config->cpu_transcoder = TRANSCODER_DSI_0;
> -		}
> +		if (trans_pipe == crtc->pipe)
> +			pipe_config->cpu_transcoder = panel_transcoder;
>  	}
>  
> +	/*
> +	 * Valid combos: none, eDP, DSI0, DSI1, DSI0+DSI1
> +	 */
> +	WARN_ON((enabled_panel_transcoders & BIT(TRANSCODER_EDP)) &&
> +		enabled_panel_transcoders != BIT(TRANSCODER_EDP));
> +
>  	power_domain = POWER_DOMAIN_TRANSCODER(pipe_config->cpu_transcoder);
>  	if (!intel_display_power_get_if_enabled(dev_priv, power_domain))
>  		return false;
> -- 
> 2.11.0
> 
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