Re: [Intel-gfx] [PATCH v8 1/5] drm/i915: Drop AUX backlight enable check for backlight control

On Wed, 2017-05-17 at 14:04 -0700, Puthikorn Voravootivat wrote:

On Wed, May 17, 2017 at 1:09 PM, Pandiyan, Dhinakaran dhinakaran.pandiyan@intel.com wrote:

    ________________________________________
    From: Puthikorn Voravootivat [puthik@google.com] on behalf of
    Puthikorn Voravootivat [puthik@chromium.org]
    Sent: Tuesday, May 16, 2017 5:33 PM
    To: intel-gfx@lists.freedesktop.org; Pandiyan, Dhinakaran
    Cc: dri-devel@lists.freedesktop.org; Jani Nikula; Navare,
    Manasi D; Stephane Marchesin; Puthikorn Voravootivat
    Subject: [PATCH v8 1/5] drm/i915: Drop AUX backlight enable
    check for backlight control


    There are some panel that
    (1) does not support display backlight enable via AUX
    (2) support display backlight adjustment via AUX
    (3) support display backlight enable via eDP BL_ENABLE pin

    The current driver required that (1) must be support to enable
    (2).
    This patch drops that requirement.

    Signed-off-by: Puthikorn Voravootivat <puthik@chromium.org>
    ---
    drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 1 -
    1 file changed, 1 deletion(-)

    diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
    b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
    index b87c5a381d6a..d32c06583e0b 100644
    --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
    +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
    @@ -165,7 +165,6 @@
    intel_dp_aux_display_control_capable(struct intel_connector
    *connector)
    * the panel can support backlight control over the aux channel
    */
    if (intel_dp->edp_dpcd[1] &
    DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP &&
    - (intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP) &&
    (intel_dp->edp_dpcd[2] &
    DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP) &&
    !((intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_PIN_ENABLE_CAP) ||
    (intel_dp->edp_dpcd[2] &
    DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP))) {
    --
    2.13.0.303.g4ebf302169-goog



    ^ still has the problem I mentioned last time. How about
    this? 


    diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
    b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
    index b87c5a3..7072bcf 100644
    --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
    +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
    @@ -28,6 +28,10 @@ static void set_aux_backlight_enable(struct
    intel_dp *intel_dp, bool enable)
     {
            uint8_t reg_val = 0;

    +       /* Early return when display use other mechanism to
    enable backlight. */
    +       if (!(intel_dp->edp_dpcd[1] &
    DP_EDP_BACKLIGHT_AUX_ENABLE_CAP))
    +               return;
    +
            if (drm_dp_dpcd_readb(&intel_dp->aux,
    DP_EDP_DISPLAY_CONTROL_REGISTER,
                                  &reg_val) < 0) {
                    DRM_DEBUG_KMS("Failed to read DPCD register 0x
    %x\n",
    @@ -165,10 +169,8 @@
    intel_dp_aux_display_control_capable(struct intel_connector
    *connector)
             * the panel can support backlight control over the
    aux channel
             */
            if (intel_dp->edp_dpcd[1] &
    DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP &&
    -           (intel_dp->edp_dpcd[1] &
    DP_EDP_BACKLIGHT_AUX_ENABLE_CAP) &&
                (intel_dp->edp_dpcd[2] &
    DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP) &&
    -           !((intel_dp->edp_dpcd[1] &
    DP_EDP_BACKLIGHT_PIN_ENABLE_CAP) ||
    -             (intel_dp->edp_dpcd[2] &
    DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP))) {
    +           !(intel_dp->edp_dpcd[2] &
    DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP)) {
                    DRM_DEBUG_KMS("AUX Backlight Control
    Supported!\n");
                    return true;
            }

This works too. I probably misunderstood your comment as I move the code to next patch in the set.

Please feel free to question any of the comments if you do not agree.

-DK

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