[PATCH 04/10] video: exynos_dp: Get pll lock before pattern set

[PATCH 04/10] video: exynos_dp: Get pll lock before pattern set

[Sean Paul]

According to the exynos datasheet (Figure 49-10), we should wait for PLL
lock before programming the training pattern when doing software eDP
link training.

Signed-off-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Mandeep Singh Baines <msb@chromium.org>
---
 drivers/video/exynos/exynos_dp_core.c |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/drivers/video/exynos/exynos_dp_core.c b/drivers/video/exynos/exynos_dp_core.c
index 3deded2..207bd7e 100644
--- a/drivers/video/exynos/exynos_dp_core.c
+++ b/drivers/video/exynos/exynos_dp_core.c
@@ -23,6 +23,8 @@
 
 #include "exynos_dp_core.h"
 
+#define PLL_MAX_TRIES 100
+
 static int exynos_dp_init_dp(struct exynos_dp_device *dp)
 {
 	exynos_dp_reset(dp);
@@ -260,7 +262,7 @@ static void exynos_dp_set_lane_lane_pre_emphasis(struct exynos_dp_device *dp,
 
 static int exynos_dp_link_start(struct exynos_dp_device *dp)
 {
-	int ret, lane, lane_count;
+	int ret, lane, lane_count, pll_tries;
 	u8 buf[4];
 
 	lane_count = dp->link_train.lane_count;
@@ -293,6 +295,16 @@ static int exynos_dp_link_start(struct exynos_dp_device *dp)
 		exynos_dp_set_lane_lane_pre_emphasis(dp,
 			PRE_EMPHASIS_LEVEL_0, lane);
 
+	/* Wait for PLL lock */
+	pll_tries = 0;
+	while (exynos_dp_get_pll_lock_status(dp) = PLL_UNLOCKED) {
+		if (pll_tries = PLL_MAX_TRIES)
+			return -ETIMEDOUT;
+
+		pll_tries++;
+		udelay(100);
+	}
+
 	/* Set training pattern 1 */
 	exynos_dp_set_training_pattern(dp, TRAINING_PTN1);
 
-- 
1.7.7.3

RE: [PATCH 04/10] video: exynos_dp: Get pll lock before pattern set

[Jingoo Han]

On Wednesday, August 08, 2012 12:54 PM Sean Paul wrote:
> 
> According to the exynos datasheet (Figure 49-10), we should wait for PLL
> lock before programming the training pattern when doing software eDP
> link training.
> 
> Signed-off-by: Sean Paul <seanpaul@chromium.org>
> Reviewed-by: Mandeep Singh Baines <msb@chromium.org>
> ---
>  drivers/video/exynos/exynos_dp_core.c |   14 +++++++++++++-
>  1 files changed, 13 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/video/exynos/exynos_dp_core.c b/drivers/video/exynos/exynos_dp_core.c
> index 3deded2..207bd7e 100644
> --- a/drivers/video/exynos/exynos_dp_core.c
> +++ b/drivers/video/exynos/exynos_dp_core.c
> @@ -23,6 +23,8 @@
> 
>  #include "exynos_dp_core.h"
> 
> +#define PLL_MAX_TRIES 100
> +
>  static int exynos_dp_init_dp(struct exynos_dp_device *dp)
>  {
>  	exynos_dp_reset(dp);
> @@ -260,7 +262,7 @@ static void exynos_dp_set_lane_lane_pre_emphasis(struct exynos_dp_device *dp,
> 
>  static int exynos_dp_link_start(struct exynos_dp_device *dp)
>  {
> -	int ret, lane, lane_count;
> +	int ret, lane, lane_count, pll_tries;
>  	u8 buf[4];
> 
>  	lane_count = dp->link_train.lane_count;
> @@ -293,6 +295,16 @@ static int exynos_dp_link_start(struct exynos_dp_device *dp)
>  		exynos_dp_set_lane_lane_pre_emphasis(dp,
>  			PRE_EMPHASIS_LEVEL_0, lane);
> 
> +	/* Wait for PLL lock */
> +	pll_tries = 0;
> +	while (exynos_dp_get_pll_lock_status(dp) = PLL_UNLOCKED) {
> +		if (pll_tries = PLL_MAX_TRIES)
> +			return -ETIMEDOUT;
> +
> +		pll_tries++;
> +		udelay(100);
> +	}
> +

You don't need to add 'PLL_MAX_TRIES', please use 'DP_TIMEOUT_LOOP_COUNT' as below:

	/* Wait for PLL lock */
	while (exynos_dp_get_pll_lock_status(dp) = PLL_UNLOCKED) {
		timeout_loop++;
		if (DP_TIMEOUT_LOOP_COUNT < timeout_loop) {
			dev_err(dp->dev, "failed to get pll lock status\n");
			return -ETIMEDOUT;
		}
		udelay(100);
	}

Also, could you use usleep_range() instead of udelay()? 


>  	/* Set training pattern 1 */
>  	exynos_dp_set_training_pattern(dp, TRAINING_PTN1);
> 
> --
> 1.7.7.3