[PATCH 12/41] drm/bridge: analogix_dp: add fast link train for eDP
Andrzej Hajda
a.hajda at samsung.com
Thu Mar 16 07:14:28 PDT 2017
On 10.03.2017 05:32, Sean Paul wrote:
> From: zain wang <wzz at rock-chips.com>
>
> We would meet a short black screen when exit PSR with the full link
> training, In this case, we should use fast link train instead of full
> link training.
>
> Signed-off-by: zain wang <wzz at rock-chips.com>
> Signed-off-by: Sean Paul <seanpaul at chromium.org>
> ---
> drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 142 ++++++++++++++++-----
> drivers/gpu/drm/bridge/analogix/analogix_dp_core.h | 3 +
> 2 files changed, 114 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> index 64d94a34874d..5bc151b0995b 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> @@ -10,17 +10,18 @@
> * option) any later version.
> */
>
> -#include <linux/module.h>
> -#include <linux/platform_device.h>
> -#include <linux/err.h>
> #include <linux/clk.h>
> -#include <linux/io.h>
> +#include <linux/component.h>
> +#include <linux/err.h>
> +#include <linux/gpio.h>
> #include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/module.h>
> #include <linux/of.h>
> #include <linux/of_gpio.h>
> -#include <linux/gpio.h>
> -#include <linux/component.h>
> #include <linux/phy/phy.h>
> +#include <linux/platform_device.h>
>
> #include <drm/drmP.h>
> #include <drm/drm_atomic_helper.h>
> @@ -35,6 +36,8 @@
>
> #define to_dp(nm) container_of(nm, struct analogix_dp_device, nm)
>
> +static const bool verify_fast_training;
> +
Quite odd debug sentinel, I am not sure if it is good practice to use
such construct.
> struct bridge_init {
> struct i2c_client *client;
> struct device_node *node;
> @@ -531,7 +534,7 @@ static int analogix_dp_process_equalizer_training(struct analogix_dp_device *dp)
> {
> int lane, lane_count, retval;
> u32 reg;
> - u8 link_align, link_status[2], adjust_request[2];
> + u8 link_align, link_status[2], adjust_request[2], spread;
>
> usleep_range(400, 401);
>
> @@ -574,6 +577,20 @@ static int analogix_dp_process_equalizer_training(struct analogix_dp_device *dp)
> dev_dbg(dp->dev, "final lane count = %.2x\n",
> dp->link_train.lane_count);
>
> + retval = drm_dp_dpcd_readb(&dp->aux, DP_MAX_DOWNSPREAD,
> + &spread);
> + if (retval != 1) {
> + dev_err(dp->dev, "failed to read downspread %d\n",
comma before %d ?
> + retval);
> + dp->fast_train_support = false;
> + } else {
> + dp->fast_train_support =
> + (spread & DP_NO_AUX_HANDSHAKE_LINK_TRAINING) ?
> + true : false;
dp->fast_train_support = !!(spread & DP_NO_AUX_HANDSHAKE_LINK_TRAINING);
or even
dp->fast_train_support = spread & DP_NO_AUX_HANDSHAKE_LINK_TRAINING;
if dp->fast_train_support is bool
> + }
> + dev_dbg(dp->dev, "fast link training %s\n",
> + dp->fast_train_support ? "supported" : "unsupported");
> +
> /* set enhanced mode if available */
> analogix_dp_set_enhanced_mode(dp);
> dp->link_train.lt_state = FINISHED;
> @@ -630,10 +647,12 @@ static void analogix_dp_get_max_rx_lane_count(struct analogix_dp_device *dp,
> *lane_count = DPCD_MAX_LANE_COUNT(data);
> }
>
> -static void analogix_dp_init_training(struct analogix_dp_device *dp,
> - enum link_lane_count_type max_lane,
> - int max_rate)
> +static int analogix_dp_full_link_train(struct analogix_dp_device *dp,
> + u32 max_lanes, u32 max_rate)
> {
> + int retval = 0;
> + bool training_finished = false;
> +
> /*
> * MACRO_RST must be applied after the PLL_LOCK to avoid
> * the DP inter pair skew issue for at least 10 us
> @@ -659,18 +678,13 @@ static void analogix_dp_init_training(struct analogix_dp_device *dp,
> }
>
> /* Setup TX lane count & rate */
> - if (dp->link_train.lane_count > max_lane)
> - dp->link_train.lane_count = max_lane;
> + if (dp->link_train.lane_count > max_lanes)
> + dp->link_train.lane_count = max_lanes;
> if (dp->link_train.link_rate > max_rate)
> dp->link_train.link_rate = max_rate;
>
> /* All DP analog module power up */
> analogix_dp_set_analog_power_down(dp, POWER_ALL, 0);
> -}
> -
> -static int analogix_dp_sw_link_training(struct analogix_dp_device *dp)
> -{
> - int retval = 0, training_finished = 0;
>
> dp->link_train.lt_state = START;
>
> @@ -705,22 +719,88 @@ static int analogix_dp_sw_link_training(struct analogix_dp_device *dp)
> return retval;
> }
>
> -static int analogix_dp_set_link_train(struct analogix_dp_device *dp,
> - u32 count, u32 bwtype)
> +static int analogix_dp_fast_link_train(struct analogix_dp_device *dp)
> {
> - int i;
> - int retval;
> + int i, ret;
> + u8 link_align, link_status[2];
> + enum pll_status status;
>
> - for (i = 0; i < DP_TIMEOUT_LOOP_COUNT; i++) {
> - analogix_dp_init_training(dp, count, bwtype);
> - retval = analogix_dp_sw_link_training(dp);
> - if (retval == 0)
> - break;
> + analogix_dp_reset_macro(dp);
>
> - usleep_range(100, 110);
> + analogix_dp_set_link_bandwidth(dp, dp->link_train.link_rate);
> + analogix_dp_set_lane_count(dp, dp->link_train.lane_count);
> +
> + for (i = 0; i < dp->link_train.lane_count; i++) {
> + analogix_dp_set_lane_link_training(dp,
> + dp->link_train.training_lane[i], i);
> }
>
> - return retval;
> + ret = readx_poll_timeout(analogix_dp_get_pll_lock_status, dp, status,
> + status != PLL_UNLOCKED, 120,
> + 120 * DP_TIMEOUT_LOOP_COUNT);
> + if (ret) {
> + DRM_DEV_ERROR(dp->dev, "Wait for pll lock failed %d\n", ret);
> + return ret;
> + }
> +
> + /* source Set training pattern 1 */
> + analogix_dp_set_training_pattern(dp, TRAINING_PTN1);
> + /* From DP spec, pattern must be on-screen for a minimum 500us */
> + usleep_range(500, 600);
> +
> + analogix_dp_set_training_pattern(dp, TRAINING_PTN2);
> + /* From DP spec, pattern must be on-screen for a minimum 500us */
> + usleep_range(500, 600);
> +
> + /* TODO: enhanced_mode?*/
> + analogix_dp_set_training_pattern(dp, DP_NONE);
> +
> + /*
> + * Useful for debugging issues with fast link training, disable for more
> + * speed
> + */
> + if (verify_fast_training) {
You can move definitions of link_status and other local variables here.
> + ret = drm_dp_dpcd_readb(&dp->aux, DP_LANE_ALIGN_STATUS_UPDATED,
> + &link_align);
> + if (ret < 0) {
> + DRM_DEV_ERROR(dp->dev, "Read align status failed %d\n",
> + ret);
> + return ret;
> + }
> +
> + ret = drm_dp_dpcd_read(&dp->aux, DP_LANE0_1_STATUS, link_status,
> + 2);
> + if (ret < 0) {
> + DRM_DEV_ERROR(dp->dev, "Read link status failed %d\n",
> + ret);
> + return ret;
> + }
> +
> + if (analogix_dp_clock_recovery_ok(link_status,
> + dp->link_train.lane_count)) {
> + DRM_DEV_ERROR(dp->dev, "Clock recovery failed\n");
> + analogix_dp_reduce_link_rate(dp);
> + return -EIO;
> + }
> +
> + if (analogix_dp_channel_eq_ok(link_status, link_align,
> + dp->link_train.lane_count)) {
> + DRM_DEV_ERROR(dp->dev, "Channel EQ failed\n");
> + analogix_dp_reduce_link_rate(dp);
> + return -EIO;
> + }
> + }
> +
> + return 0;
> +}
> +
> +static int analogix_dp_train_link(struct analogix_dp_device *dp)
> +{
> + if (dp->fast_train_support)
> + return analogix_dp_fast_link_train(dp);
> +
> + return analogix_dp_full_link_train(dp, dp->video_info.max_lane_count,
> + dp->video_info.max_link_rate);
> }
>
> static int analogix_dp_config_video(struct analogix_dp_device *dp)
> @@ -853,10 +933,10 @@ static void analogix_dp_commit(struct analogix_dp_device *dp)
> DRM_ERROR("failed to disable the panel\n");
> }
>
> - ret = analogix_dp_set_link_train(dp, dp->video_info.max_lane_count,
> - dp->video_info.max_link_rate);
> + ret = readx_poll_timeout(analogix_dp_train_link, dp, ret, !ret, 100,
> + DP_TIMEOUT_TRAINING_US * 5);
> if (ret) {
> - dev_err(dp->dev, "unable to do link train\n");
> + dev_err(dp->dev, "unable to do link train, ret=%d\n", ret);
And here we have ", ret=%d\n". Maybe it would be good to make it
consistent across whole driver.
Another issue with consistency in DRM_DEV_ERROR vs dev_err.
Regards
Andrzej
> return;
> }
>
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
> index e135a42cb19e..920607d7eb3e 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
> @@ -20,6 +20,8 @@
> #define MAX_CR_LOOP 5
> #define MAX_EQ_LOOP 5
>
> +/* Training takes 22ms if AUX channel comm fails. Use this as retry interval */
> +#define DP_TIMEOUT_TRAINING_US 22000
> #define DP_TIMEOUT_PSR_LOOP_MS 300
>
> /* DP_MAX_LANE_COUNT */
> @@ -171,6 +173,7 @@ struct analogix_dp_device {
> int hpd_gpio;
> bool force_hpd;
> bool psr_enable;
> + bool fast_train_support;
>
> struct mutex panel_lock;
> bool panel_is_modeset;
More information about the Linux-rockchip
mailing list