[Intel-gfx] [PATCHv3 1/4] drm/i915: Make finding unused crtc as a generic function

[R, Durgadoss]

>-----Original Message-----
>From: Ander Conselvan De Oliveira [mailto:conselvan2 at gmail.com]
>Sent: Monday, April 11, 2016 6:06 PM
>To: R, Durgadoss <durgadoss.r at intel.com>; intel-gfx at lists.freedesktop.org
>Cc: ville.syrjala at linux.intel.com
>Subject: Re: [PATCHv3 1/4] drm/i915: Make finding unused crtc as a generic function
>
>On Wed, 2016-04-06 at 17:23 +0530, Durgadoss R wrote:
>> Looping over the crtc list and finding an unused crtc
>> has other users like upfront link training. Hence move it to
>> a common function to re-use the logic.
>>
>> v3:
>> * Added kernel Doc and removed an invalid comment (Ander)
>> * Rebased on top of latest code which includes locking
>>   for state->enable usage.
>> v2:
>> * Made this as a separate function instead of having it
>>   inside upfront link train code.
>>
>> Signed-off-by: Durgadoss R <durgadoss.r at intel.com>
>> ---
>>  drivers/gpu/drm/i915/intel_display.c | 74 +++++++++++++++++++++--------------
>> -
>>  drivers/gpu/drm/i915/intel_drv.h     |  2 +
>>  2 files changed, 45 insertions(+), 31 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_display.c
>> b/drivers/gpu/drm/i915/intel_display.c
>> index e6b5ee5..3c1fbcd 100644
>> --- a/drivers/gpu/drm/i915/intel_display.c
>> +++ b/drivers/gpu/drm/i915/intel_display.c
>> @@ -10366,6 +10366,43 @@ static int intel_modeset_setup_plane_state(struct
>> drm_atomic_state *state,
>>  	return 0;
>>  }
>>
>> +/**
>> + * intel_get_unused_crtc - Find an unused crtc for the given encoder
>> + * @encoder: drm_encoder structure
>> + * @ctx: ctx pointer to use with locking
>> + *
>> + * This function tries to find an unused crtc that can drive
>> + * the given encoder. Returns NULL on failure.
>
>This doesn't match the code below, since it now returns an unused crtc or an
>ERR_PTR. It never returns NULL.

If the 'state->enable'  is set for all crtcs, then I think it can return a NULL.
Anyway, will fix the comment so say "Null or an error pointer" on failure.

Thanks,
Durga

>
>Ander
>
>> + */
>> +struct drm_crtc *intel_get_unused_crtc(struct drm_encoder *encoder,
>> +				struct drm_modeset_acquire_ctx *ctx)
>> +{
>> +	struct drm_crtc *possible_crtc;
>> +	struct drm_crtc *crtc = NULL;
>> +	struct drm_device *dev = encoder->dev;
>> +	int ret, i = -1;
>> +
>> +	for_each_crtc(dev, possible_crtc) {
>> +		i++;
>> +		if (!(encoder->possible_crtcs & (1 << i)))
>> +			continue;
>> +
>> +		ret = drm_modeset_lock(&possible_crtc->mutex, ctx);
>> +		if (ret)
>> +			return ERR_PTR(ret);
>> +
>> +		if (possible_crtc->state->enable) {
>> +			drm_modeset_unlock(&possible_crtc->mutex);
>> +			continue;
>> +		}
>> +
>> +		crtc = possible_crtc;
>> +		break;
>> +	}
>> +
>> +	return crtc;
>> +}
>> +
>>  bool intel_get_load_detect_pipe(struct drm_connector *connector,
>>  				struct drm_display_mode *mode,
>>  				struct intel_load_detect_pipe *old,
>> @@ -10374,7 +10411,6 @@ bool intel_get_load_detect_pipe(struct drm_connector
>> *connector,
>>  	struct intel_crtc *intel_crtc;
>>  	struct intel_encoder *intel_encoder =
>>  		intel_attached_encoder(connector);
>> -	struct drm_crtc *possible_crtc;
>>  	struct drm_encoder *encoder = &intel_encoder->base;
>>  	struct drm_crtc *crtc = NULL;
>>  	struct drm_device *dev = encoder->dev;
>> @@ -10383,7 +10419,7 @@ bool intel_get_load_detect_pipe(struct drm_connector
>> *connector,
>>  	struct drm_atomic_state *state = NULL, *restore_state = NULL;
>>  	struct drm_connector_state *connector_state;
>>  	struct intel_crtc_state *crtc_state;
>> -	int ret, i = -1;
>> +	int ret;
>>
>>  	DRM_DEBUG_KMS("[CONNECTOR:%d:%s], [ENCODER:%d:%s]\n",
>>  		      connector->base.id, connector->name,
>> @@ -10413,39 +10449,15 @@ retry:
>>  		ret = drm_modeset_lock(&crtc->mutex, ctx);
>>  		if (ret)
>>  			goto fail;
>> -
>> -		/* Make sure the crtc and connector are running */
>> -		goto found;
>> -	}
>> -
>> -	/* Find an unused one (if possible) */
>> -	for_each_crtc(dev, possible_crtc) {
>> -		i++;
>> -		if (!(encoder->possible_crtcs & (1 << i)))
>> -			continue;
>> -
>> -		ret = drm_modeset_lock(&possible_crtc->mutex, ctx);
>> -		if (ret)
>> +	} else {
>> +		crtc = intel_get_unused_crtc(encoder, ctx);
>> +		if (IS_ERR_OR_NULL(crtc)) {
>> +			ret = PTR_ERR_OR_ZERO(crtc);
>> +			DRM_DEBUG_KMS("no pipe available for load-detect\n");
>>  			goto fail;
>> -
>> -		if (possible_crtc->state->enable) {
>> -			drm_modeset_unlock(&possible_crtc->mutex);
>> -			continue;
>>  		}
>> -
>> -		crtc = possible_crtc;
>> -		break;
>> -	}
>> -
>> -	/*
>> -	 * If we didn't find an unused CRTC, don't use any.
>> -	 */
>> -	if (!crtc) {
>> -		DRM_DEBUG_KMS("no pipe available for load-detect\n");
>> -		goto fail;
>>  	}
>>
>> -found:
>>  	intel_crtc = to_intel_crtc(crtc);
>>
>>  	ret = drm_modeset_lock(&crtc->primary->mutex, ctx);
>> diff --git a/drivers/gpu/drm/i915/intel_drv.h
>> b/drivers/gpu/drm/i915/intel_drv.h
>> index 9255b56..3873af5 100644
>> --- a/drivers/gpu/drm/i915/intel_drv.h
>> +++ b/drivers/gpu/drm/i915/intel_drv.h
>> @@ -1152,6 +1152,8 @@ bool intel_get_load_detect_pipe(struct drm_connector
>> *connector,
>>  void intel_release_load_detect_pipe(struct drm_connector *connector,
>>  				    struct intel_load_detect_pipe *old,
>>  				    struct drm_modeset_acquire_ctx *ctx);
>> +struct drm_crtc *intel_get_unused_crtc(struct drm_encoder *encoder,
>> +				struct drm_modeset_acquire_ctx *ctx);
>>  int intel_pin_and_fence_fb_obj(struct drm_framebuffer *fb,
>>  			       unsigned int rotation);
>>  struct drm_framebuffer *