linux-kernel - Re: [RFC v4 05/11] drm/i915/dpcd_bl: Cleanup intel_dp_aux_vesa_enable

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Message-ID: <87h7mhcyos.fsf@intel.com>
Date:   Fri, 12 Feb 2021 13:28:35 +0200
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     Lyude Paul <lyude@...hat.com>, dri-devel@...ts.freedesktop.org,
        nouveau@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org
Cc:     Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Sean Paul <seanpaul@...omium.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [RFC v4 05/11] drm/i915/dpcd_bl: Cleanup intel_dp_aux_vesa_enable_backlight() a bit

On Mon, 08 Feb 2021, Lyude Paul <lyude@...hat.com> wrote:
> Get rid of the extraneous switch case in here, and just open code
> edp_backlight_mode as we only ever use it once.
>
> v4:
> * Check that backlight mode is DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD, not
>   DP_EDP_BACKLIGHT_CONTROL_MODE_MASK - imirkin
>
> Signed-off-by: Lyude Paul <lyude@...hat.com>
> ---
>  .../gpu/drm/i915/display/intel_dp_aux_backlight.c | 15 ++-------------
>  1 file changed, 2 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> index c37ccc8538cb..57218faed4a3 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> @@ -382,7 +382,7 @@ intel_dp_aux_vesa_enable_backlight(const struct intel_crtc_state *crtc_state,
>  	struct intel_dp *intel_dp = intel_attached_dp(connector);
>  	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
>  	struct intel_panel *panel = &connector->panel;
> -	u8 dpcd_buf, new_dpcd_buf, edp_backlight_mode;
> +	u8 dpcd_buf, new_dpcd_buf;
>  	u8 pwmgen_bit_count = panel->backlight.edp.vesa.pwmgen_bit_count;
>  
>  	if (drm_dp_dpcd_readb(&intel_dp->aux,
> @@ -393,12 +393,8 @@ intel_dp_aux_vesa_enable_backlight(const struct intel_crtc_state *crtc_state,
>  	}
>  
>  	new_dpcd_buf = dpcd_buf;
> -	edp_backlight_mode = dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
>  
> -	switch (edp_backlight_mode) {
> -	case DP_EDP_BACKLIGHT_CONTROL_MODE_PWM:
> -	case DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET:
> -	case DP_EDP_BACKLIGHT_CONTROL_MODE_PRODUCT:
> +	if ((dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) != DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD) {
>  		new_dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
>  		new_dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
>  
> @@ -406,13 +402,6 @@ intel_dp_aux_vesa_enable_backlight(const struct intel_crtc_state *crtc_state,
>  				       pwmgen_bit_count) != 1)

What baseline is this on? None that I can think of have the above != 1,
they're all < 0 AFAICT.

BR,
Jani.


>  			drm_dbg_kms(&i915->drm,
>  				    "Failed to write aux pwmgen bit count\n");
> -
> -		break;
> -
> -	/* Do nothing when it is already DPCD mode */
> -	case DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD:
> -	default:
> -		break;
>  	}
>  
>  	if (panel->backlight.edp.vesa.pwm_freq_pre_divider) {

-- 
Jani Nikula, Intel Open Source Graphics Center