Commit 79c1da7c authored by Tomeu Vizoso's avatar Tomeu Vizoso Committed by Sean Paul
Browse files

drm/dp: add helpers for capture of frame CRCs 



Adds helpers for starting and stopping capture of frame CRCs through the
DPCD. When capture is on, a worker waits for vblanks and retrieves the
frame CRC to put it in the queue on the CRTC that is using the
eDP connector, so it's passed to userspace.

v2: Reuse drm_crtc_wait_one_vblank
    Update locking, as drm_crtc_add_crc_entry now takes the lock

v3: Don't call wake_up_interruptible directly, that's now done in
    drm_crtc_add_crc_entry.

v4: Style fixes (Sean Paul)
    Reworked retry of CRC reads (Sean Paul)
    Flush worker after stopping CRC generationa (Sean Paul)

v5: Move back to make the retry explicitly once

v6: Set and use the drm_crtc backpointer (Sean Paul)

Signed-off-by: default avatarTomeu Vizoso <tomeu.vizoso@collabora.com>
Signed-off-by: default avatarSean Paul <seanpaul@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170303133936.14964-3-tomeu.vizoso@collabora.com
parent 4bb310fd

drivers/gpu/drm/drm_dp_helper.c

+126 −0
Original line number Diff line number Diff line
@@ -981,6 +981,78 @@ static const struct i2c_lock_operations drm_dp_i2c_lock_ops = { 
	.unlock_bus = unlock_bus,

};



static int drm_dp_aux_get_crc(struct drm_dp_aux *aux, u8 *crc)

{

	u8 buf, count;

	int ret;



	ret = drm_dp_dpcd_readb(aux, DP_TEST_SINK, &buf);

	if (ret < 0)

		return ret;



	WARN_ON(!(buf & DP_TEST_SINK_START));



	ret = drm_dp_dpcd_readb(aux, DP_TEST_SINK_MISC, &buf);

	if (ret < 0)

		return ret;



	count = buf & DP_TEST_COUNT_MASK;

	if (count == aux->crc_count)

		return -EAGAIN; /* No CRC yet */



	aux->crc_count = count;



	/*

	 * At DP_TEST_CRC_R_CR, there's 6 bytes containing CRC data, 2 bytes

	 * per component (RGB or CrYCb).

	 */

	ret = drm_dp_dpcd_read(aux, DP_TEST_CRC_R_CR, crc, 6);

	if (ret < 0)

		return ret;



	return 0;

}



static void drm_dp_aux_crc_work(struct work_struct *work)

{

	struct drm_dp_aux *aux = container_of(work, struct drm_dp_aux,

					      crc_work);

	struct drm_crtc *crtc;

	u8 crc_bytes[6];

	uint32_t crcs[3];

	int ret;



	if (WARN_ON(!aux->crtc))

		return;



	crtc = aux->crtc;

	while (crtc->crc.opened) {

		drm_crtc_wait_one_vblank(crtc);

		if (!crtc->crc.opened)

			break;



		ret = drm_dp_aux_get_crc(aux, crc_bytes);

		if (ret == -EAGAIN) {

			usleep_range(1000, 2000);

			ret = drm_dp_aux_get_crc(aux, crc_bytes);

		}



		if (ret == -EAGAIN) {

			DRM_DEBUG_KMS("Get CRC failed after retrying: %d\n",

				      ret);

			continue;

		} else if (ret) {

			DRM_DEBUG_KMS("Failed to get a CRC: %d\n", ret);

			continue;

		}



		crcs[0] = crc_bytes[0] | crc_bytes[1] << 8;

		crcs[1] = crc_bytes[2] | crc_bytes[3] << 8;

		crcs[2] = crc_bytes[4] | crc_bytes[5] << 8;

		drm_crtc_add_crc_entry(crtc, false, 0, crcs);

	}

}



/**

 * drm_dp_aux_init() - minimally initialise an aux channel

 * @aux: DisplayPort AUX channel
@@ -993,6 +1065,7 @@ static const struct i2c_lock_operations drm_dp_i2c_lock_ops = { 
void drm_dp_aux_init(struct drm_dp_aux *aux)

{

	mutex_init(&aux->hw_mutex);

	INIT_WORK(&aux->crc_work, drm_dp_aux_crc_work);



	aux->ddc.algo = &drm_dp_i2c_algo;

	aux->ddc.algo_data = aux;
@@ -1081,3 +1154,56 @@ int drm_dp_psr_setup_time(const u8 psr_cap[EDP_PSR_RECEIVER_CAP_SIZE]) 
EXPORT_SYMBOL(drm_dp_psr_setup_time);



#undef PSR_SETUP_TIME



/**

 * drm_dp_start_crc() - start capture of frame CRCs

 * @aux: DisplayPort AUX channel

 *

 * Returns 0 on success or a negative error code on failure.

 */

int drm_dp_start_crc(struct drm_dp_aux *aux, struct drm_crtc *crtc)

{

	u8 buf;

	int ret;



	ret = drm_dp_dpcd_readb(aux, DP_TEST_SINK, &buf);

	if (ret < 0)

		return ret;



	ret = drm_dp_dpcd_writeb(aux, DP_TEST_SINK, buf | DP_TEST_SINK_START);

	if (ret < 0)

		return ret;



	aux->crc_count = 0;

	aux->crtc = crtc;

	schedule_work(&aux->crc_work);



	return 0;

}

EXPORT_SYMBOL(drm_dp_start_crc);



/**

 * drm_dp_stop_crc() - stop capture of frame CRCs

 * @aux: DisplayPort AUX channel

 *

 * Returns 0 on success or a negative error code on failure.

 */

int drm_dp_stop_crc(struct drm_dp_aux *aux)

{

	u8 buf;

	int ret;



	ret = drm_dp_dpcd_readb(aux, DP_TEST_SINK, &buf);

	if (ret < 0)

		return ret;



	ret = drm_dp_dpcd_writeb(aux, DP_TEST_SINK, buf & ~DP_TEST_SINK_START);

	if (ret < 0)

		return ret;



	flush_work(&aux->crc_work);

	aux->crtc = NULL;



	return 0;

}

EXPORT_SYMBOL(drm_dp_stop_crc);

include/drm/drm_dp_helper.h

+7 −0
Original line number Diff line number Diff line
@@ -734,6 +734,8 @@ struct drm_dp_aux_msg { 
 * @dev: pointer to struct device that is the parent for this AUX channel

 * @crtc: backpointer to the crtc that is currently using this AUX channel

 * @hw_mutex: internal mutex used for locking transfers

 * @crc_work: worker that captures CRCs for each frame

 * @crc_count: counter of captured frame CRCs

 * @transfer: transfers a message representing a single AUX transaction

 *

 * The .dev field should be set to a pointer to the device that implements
@@ -771,6 +773,8 @@ struct drm_dp_aux { 
	struct device *dev;

	struct drm_crtc *crtc;

	struct mutex hw_mutex;

	struct work_struct crc_work;

	u8 crc_count;

	ssize_t (*transfer)(struct drm_dp_aux *aux,

			    struct drm_dp_aux_msg *msg);

	/**
@@ -849,4 +853,7 @@ void drm_dp_aux_init(struct drm_dp_aux *aux); 
int drm_dp_aux_register(struct drm_dp_aux *aux);

void drm_dp_aux_unregister(struct drm_dp_aux *aux);



int drm_dp_start_crc(struct drm_dp_aux *aux, struct drm_crtc *crtc);

int drm_dp_stop_crc(struct drm_dp_aux *aux);



#endif /* _DRM_DP_HELPER_H_ */

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