Sorry for the wait. This is not a complete review, just some quick
comments for now.
On Tue, 2017-04-18 at 16:48 -0700, Puthikorn Voravootivat wrote:
> Currently the intel_dp_aux_backlight driver requires eDP panel
> to not also support backlight adjustment via PWM pin to use
> this driver.
>
> This force the eDP panel that support both ways of backlight
> adjustment to do it via PWM pin.
>
> This patch adds the new prefer DPCD mode in the i915_param
> to make it enable to prefer DPCD over the PWM via kernel param.
>
> This patch also add a check to DP_EDP_BACKLIGHT_AUX_ENABLE_CAP
> in set_aux_backlight_enable() since the backlight enablement
> can be done via BL_ENABLE eDP connector pin in the case that
> it does not support doing that via AUX.
>
> Signed-off-by: Puthikorn Voravootivat <puthik@xxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_params.c | 6 ++---
> drivers/gpu/drm/i915/i915_params.h | 2 +-
> drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 33 +++++++++++++++++++--------
> 3 files changed, 27 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> index b6a7e363d076..960393dd5edf 100644
> --- a/drivers/gpu/drm/i915/i915_params.c
> +++ b/drivers/gpu/drm/i915/i915_params.c
> @@ -63,7 +63,7 @@ struct i915_params i915 __read_mostly = {
> .huc_firmware_path = NULL,
> .enable_dp_mst = true,
> .inject_load_failure = 0,
> - .enable_dpcd_backlight = false,
> + .enable_dpcd_backlight = 0,
> .enable_gvt = false,
> };
>
> @@ -246,9 +246,9 @@ MODULE_PARM_DESC(enable_dp_mst,
> module_param_named_unsafe(inject_load_failure, i915.inject_load_failure, uint, 0400);
> MODULE_PARM_DESC(inject_load_failure,
> "Force an error after a number of failure check points (0:disabled (default), N:force failure at the Nth failure check point)");
> -module_param_named(enable_dpcd_backlight, i915.enable_dpcd_backlight, bool, 0600);
> +module_param_named(enable_dpcd_backlight, i915.enable_dpcd_backlight, int, 0600);
> MODULE_PARM_DESC(enable_dpcd_backlight,
> - "Enable support for DPCD backlight control (default:false)");
> + "Enable support for DPCD backlight control (0:disable (default), 1:prefer PWM pin, 2: prefer DPCD)");
I looked at other int parameters, -1=default, 0=disable(prefer PWM in
your case), 1=enable(prefer DPCD) seems like the more common way to do
this.
>
> module_param_named(enable_gvt, i915.enable_gvt, bool, 0400);
> MODULE_PARM_DESC(enable_gvt,
> diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
> index 34148cc8637c..bf6e2c60f697 100644
> --- a/drivers/gpu/drm/i915/i915_params.h
> +++ b/drivers/gpu/drm/i915/i915_params.h
> @@ -51,6 +51,7 @@
> func(int, use_mmio_flip); \
> func(int, mmio_debug); \
> func(int, edp_vswing); \
> + func(int, enable_dpcd_backlight); \
> func(unsigned int, inject_load_failure); \
> /* leave bools at the end to not create holes */ \
> func(bool, alpha_support); \
> @@ -66,7 +67,6 @@
> func(bool, verbose_state_checks); \
> func(bool, nuclear_pageflip); \
> func(bool, enable_dp_mst); \
> - func(bool, enable_dpcd_backlight); \
> func(bool, enable_gvt)
>
> #define MEMBER(T, member) T member
> diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> index 6532e226db29..42f73d9a3ccf 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,
> ®_val) < 0) {
> DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
> @@ -138,27 +142,36 @@ static bool
> intel_dp_aux_display_control_capable(struct intel_connector *connector)
> {
> struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
> + bool supported;
>
> /* Check the eDP Display control capabilities registers to determine if
> * 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[1] & DP_EDP_BACKLIGHT_PIN_ENABLE_CAP) ||
> - (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP))) {
> - DRM_DEBUG_KMS("AUX Backlight Control Supported!\n");
> - return true;
> + switch (i915.enable_dpcd_backlight) {
> + case 1: /* prefer PWM pin */
> + supported = (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[1] & DP_EDP_BACKLIGHT_PIN_ENABLE_CAP) &&
> + !(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP);
> + break;
> + case 2: /* prefer DPCD */
> + supported = (intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP) &&
> + (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP);
> + break;
> + default:
> + supported = false;
> }
> - return false;
> +
> + if (supported)
> + DRM_DEBUG_KMS("AUX Backlight Control Supported!\n");
> +
> + return supported;
If i915.enable_dpcd_backlight = 0, aren't you returning an uninitialized
variable here?
-DK
> }
>
> int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
> {
> struct intel_panel *panel = &intel_connector->panel;
>
> - if (!i915.enable_dpcd_backlight)
> - return -ENODEV;
> -
> if (!intel_dp_aux_display_control_capable(intel_connector))
> return -ENODEV;
>
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