Commit 6a127160 authored by Thierry Reding's avatar Thierry Reding
Browse files

drm/tegra: dp: Add support for eDP link rates 



Parses additional link rates from DPCD if the sink supports eDP 1.4.

Signed-off-by: default avatarThierry Reding <treding@nvidia.com>
parent 01f09f24

drivers/gpu/drm/tegra/dp.c

+127 −0
Original line number Diff line number Diff line
@@ -33,6 +33,8 @@ void drm_dp_link_caps_copy(struct drm_dp_link_caps *dest, 


static void drm_dp_link_reset(struct drm_dp_link *link)

{

	unsigned int i;



	if (!link)

		return;
@@ -47,6 +49,111 @@ static void drm_dp_link_reset(struct drm_dp_link *link) 


	link->rate = 0;

	link->lanes = 0;



	for (i = 0; i < DP_MAX_SUPPORTED_RATES; i++)

		link->rates[i] = 0;



	link->num_rates = 0;

}



/**

 * drm_dp_link_add_rate() - add a rate to the list of supported rates

 * @link: the link to add the rate to

 * @rate: the rate to add

 *

 * Add a link rate to the list of supported link rates.

 *

 * Returns:

 * 0 on success or one of the following negative error codes on failure:

 * - ENOSPC if the maximum number of supported rates has been reached

 * - EEXISTS if the link already supports this rate

 *

 * See also:

 * drm_dp_link_remove_rate()

 */

int drm_dp_link_add_rate(struct drm_dp_link *link, unsigned long rate)

{

	unsigned int i, pivot;



	if (link->num_rates == DP_MAX_SUPPORTED_RATES)

		return -ENOSPC;



	for (pivot = 0; pivot < link->num_rates; pivot++)

		if (rate <= link->rates[pivot])

			break;



	if (pivot != link->num_rates && rate == link->rates[pivot])

		return -EEXIST;



	for (i = link->num_rates; i > pivot; i--)

		link->rates[i] = link->rates[i - 1];



	link->rates[pivot] = rate;

	link->num_rates++;



	return 0;

}



/**

 * drm_dp_link_remove_rate() - remove a rate from the list of supported rates

 * @link: the link from which to remove the rate

 * @rate: the rate to remove

 *

 * Removes a link rate from the list of supported link rates.

 *

 * Returns:

 * 0 on success or one of the following negative error codes on failure:

 * - EINVAL if the specified rate is not among the supported rates

 *

 * See also:

 * drm_dp_link_add_rate()

 */

int drm_dp_link_remove_rate(struct drm_dp_link *link, unsigned long rate)

{

	unsigned int i;



	for (i = 0; i < link->num_rates; i++)

		if (rate == link->rates[i])

			break;



	if (i == link->num_rates)

		return -EINVAL;



	link->num_rates--;



	while (i < link->num_rates) {

		link->rates[i] = link->rates[i + 1];

		i++;

	}



	return 0;

}



/**

 * drm_dp_link_update_rates() - normalize the supported link rates array

 * @link: the link for which to normalize the supported link rates

 *

 * Users should call this function after they've manually modified the array

 * of supported link rates. This function removes any stale entries, compacts

 * the array and updates the supported link rate count. Note that calling the

 * drm_dp_link_remove_rate() function already does this janitorial work.

 *

 * See also:

 * drm_dp_link_add_rate(), drm_dp_link_remove_rate()

 */

void drm_dp_link_update_rates(struct drm_dp_link *link)

{

	unsigned int i, count = 0;



	for (i = 0; i < link->num_rates; i++) {

		if (link->rates[i] != 0)

			link->rates[count++] = link->rates[i];

	}



	for (i = count; i < link->num_rates; i++)

		link->rates[i] = 0;



	link->num_rates = count;

}



/**
@@ -125,6 +232,26 @@ int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link) 
	link->rate = link->max_rate;

	link->lanes = link->max_lanes;



	/* Parse SUPPORTED_LINK_RATES from eDP 1.4 */

	if (link->edp >= 0x14) {

		u8 supported_rates[DP_MAX_SUPPORTED_RATES * 2];

		unsigned int i;

		u16 rate;



		err = drm_dp_dpcd_read(aux, DP_SUPPORTED_LINK_RATES,

				       supported_rates,

				       sizeof(supported_rates));

		if (err < 0)

			return err;



		for (i = 0; i < DP_MAX_SUPPORTED_RATES; i++) {

			rate = supported_rates[i * 2 + 1] << 8 |

			       supported_rates[i * 2 + 0];



			drm_dp_link_add_rate(link, rate * 200);

		}

	}



	return 0;

}

drivers/gpu/drm/tegra/dp.h

+9 −0
Original line number Diff line number Diff line
@@ -66,6 +66,8 @@ void drm_dp_link_caps_copy(struct drm_dp_link_caps *dest, 
 * @edp: eDP revision (0x11: eDP 1.1, 0x12: eDP 1.2, ...)

 * @rate: currently configured link rate

 * @lanes: currently configured number of lanes

 * @rates: additional supported link rates in kHz (eDP 1.4)

 * @num_rates: number of additional supported link rates (eDP 1.4)

 */

struct drm_dp_link {

	unsigned char revision;
@@ -87,8 +89,15 @@ struct drm_dp_link { 


	unsigned int rate;

	unsigned int lanes;



	unsigned long rates[DP_MAX_SUPPORTED_RATES];

	unsigned int num_rates;

};



int drm_dp_link_add_rate(struct drm_dp_link *link, unsigned long rate);

int drm_dp_link_remove_rate(struct drm_dp_link *link, unsigned long rate);

void drm_dp_link_update_rates(struct drm_dp_link *link);



int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link);

int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link);

int drm_dp_link_power_down(struct drm_dp_aux *aux, struct drm_dp_link *link);