Re: [PATCH v2 drm-dp 2/7] drm/hisilicon/hibmc: Add dp serdes cfg in dp process

[Yongbang Shi <shiyongbang@huawei.com>]

> On Mon, Feb 10, 2025 at 10:49:54PM +0800, Yongbang Shi wrote:
>> From: Baihan Li <libaihan@huawei.com>
>>
>> Add dp serdes cfg in link training process, and related adapting
>> and modificating. We change some init values about training,
> Imperative language, please. Use 'change', not 'we change'.
>
>> because we want completely to negotiation process, so we start with
>> the maximum rate and the electrical characteristic level is 0.
>>
>> Signed-off-by: Baihan Li <libaihan@huawei.com>
>> Signed-off-by: Yongbang Shi <shiyongbang@huawei.com>
>> ---
>> ChangeLog:
>> v1 -> v2:
>>    - splittting the patch and add more detailed the changes in the commit message, suggested by Dmitry Baryshkov.
>> ---
>>   .../gpu/drm/hisilicon/hibmc/dp/dp_config.h    |  1 +
>>   drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c    |  6 +++-
>>   drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c  | 33 ++++++++++++++++---
>>   drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h   |  1 +
>>   .../gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c   |  8 ++---
>>   5 files changed, 38 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_config.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_config.h
>> index 74dd9956144e..c5feef8dc27d 100644
>> --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_config.h
>> +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_config.h
>> @@ -15,5 +15,6 @@
>>   #define HIBMC_DP_CLK_EN			0x7
>>   #define HIBMC_DP_SYNC_EN_MASK		0x3
>>   #define HIBMC_DP_LINK_RATE_CAL		27
>> +#define HIBMC_DP_SYNC_DELAY(lanes)	((lanes) == 0x2 ? 86 : 46)
>>   
>>   #endif
>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
>> index 39fd3687efca..ee1ff205ff56 100644
>> --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
>> +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
>> @@ -3,6 +3,7 @@
>>   
>>   #include <linux/io.h>
>>   #include <linux/delay.h>
>> +#include <drm/drm_managed.h>
>>   #include "dp_config.h"
>>   #include "dp_comm.h"
>>   #include "dp_reg.h"
>> @@ -73,6 +74,9 @@ static void hibmc_dp_set_sst(struct hibmc_dp_dev *dp, struct drm_display_mode *m
>>   				 HIBMC_DP_CFG_STREAM_HTOTAL_SIZE, htotal_size);
>>   	hibmc_dp_reg_write_field(dp, HIBMC_DP_VIDEO_HORIZONTAL_SIZE,
>>   				 HIBMC_DP_CFG_STREAM_HBLANK_SIZE, hblank_size);
>> +	hibmc_dp_reg_write_field(dp, HIBMC_DP_VIDEO_PACKET,
>> +				 HIBMC_DP_CFG_STREAM_SYNC_CALIBRATION,
>> +				 HIBMC_DP_SYNC_DELAY(dp->link.cap.lanes));
>>   }
>>   
>>   static void hibmc_dp_link_cfg(struct hibmc_dp_dev *dp, struct drm_display_mode *mode)
>> @@ -170,7 +174,7 @@ int hibmc_dp_hw_init(struct hibmc_dp *dp)
>>   		return -EAGAIN;
>>   
>>   	dp_dev->link.cap.lanes = 0x2;
>> -	dp_dev->link.cap.link_rate = DP_LINK_BW_2_7;
>> +	dp_dev->link.cap.link_rate = DP_LINK_BW_8_1;
>>   
>>   	/* hdcp data */
>>   	writel(HIBMC_DP_HDCP, dp_dev->base + HIBMC_DP_HDCP_CFG);
>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c
>> index f6355c16cc0a..43a4b656493f 100644
>> --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c
>> +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c
>> @@ -6,6 +6,7 @@
>>   #include <drm/drm_print.h>
>>   #include "dp_comm.h"
>>   #include "dp_reg.h"
>> +#include "dp_serdes.h"
>>   
>>   #define HIBMC_EQ_MAX_RETRY 5
>>   
>> @@ -108,7 +109,11 @@ static int hibmc_dp_link_training_cr_pre(struct hibmc_dp_dev *dp)
>>   		return ret;
>>   
>>   	for (i = 0; i < dp->link.cap.lanes; i++)
>> -		train_set[i] = DP_TRAIN_VOLTAGE_SWING_LEVEL_2;
>> +		train_set[i] = DP_TRAIN_VOLTAGE_SWING_LEVEL_0;
>> +
>> +	ret = hibmc_dp_serdes_set_tx_cfg(dp, dp->link.train_set);
>> +	if (ret)
>> +		return ret;
>>   
>>   	ret = drm_dp_dpcd_write(&dp->aux, DP_TRAINING_LANE0_SET, train_set, dp->link.cap.lanes);
>>   	if (ret != dp->link.cap.lanes) {
>> @@ -137,21 +142,28 @@ static bool hibmc_dp_link_get_adjust_train(struct hibmc_dp_dev *dp,
>>   	return false;
>>   }
>>   
>> -static inline int hibmc_dp_link_reduce_rate(struct hibmc_dp_dev *dp)
>> +static int hibmc_dp_link_reduce_rate(struct hibmc_dp_dev *dp)
>>   {
>> +	u8 rate = 0;
>> +
>>   	switch (dp->link.cap.link_rate) {
>>   	case DP_LINK_BW_2_7:
>>   		dp->link.cap.link_rate = DP_LINK_BW_1_62;
>> -		return 0;
>> +		rate = DP_SERDES_BW_1_62;
>> +		break;
>>   	case DP_LINK_BW_5_4:
>>   		dp->link.cap.link_rate = DP_LINK_BW_2_7;
>> -		return 0;
>> +		rate = DP_SERDES_BW_2_7;
>> +		break;
>>   	case DP_LINK_BW_8_1:
>>   		dp->link.cap.link_rate = DP_LINK_BW_5_4;
>> -		return 0;
>> +		rate = DP_SERDES_BW_5_4;
>> +		break;
>>   	default:
>>   		return -EINVAL;
>>   	}
>> +
>> +	return hibmc_dp_serdes_rate_switch(rate, dp);
> This looks like:
>
> if (dp->link.cap.link_rate == DP_LINK_BW_1_62)
>      return -EINVAL;
>
> dp->link.cap.link_rate++;
> return hibmc_dp_serdes_rate_switch(rate, dp);

We need map DP_LINK_BW_2_7 to DP_SERDES_BW's value firstly, which is for our SERDES' register cfg.
This value is not like 0x6, 0xa, etc.


>>   }
>>   
>>   static inline int hibmc_dp_link_reduce_lane(struct hibmc_dp_dev *dp)
>> @@ -159,6 +171,7 @@ static inline int hibmc_dp_link_reduce_lane(struct hibmc_dp_dev *dp)
>>   	switch (dp->link.cap.lanes) {
>>   	case 0x2:
>>   		dp->link.cap.lanes--;
>> +		drm_warn(dp->dev, "dp link training reduce to 1 lane\n");
> drm_dbg
>
>>   		break;
>>   	case 0x1:
>>   		drm_err(dp->dev, "dp link training reduce lane failed, already reach minimum\n");
>> @@ -206,6 +219,11 @@ static int hibmc_dp_link_training_cr(struct hibmc_dp_dev *dp)
>>   		}
>>   
>>   		level_changed = hibmc_dp_link_get_adjust_train(dp, lane_status);
>> +
>> +		ret = hibmc_dp_serdes_set_tx_cfg(dp, dp->link.train_set);
>> +		if (ret)
>> +			return ret;
>> +
>>   		ret = drm_dp_dpcd_write(&dp->aux, DP_TRAINING_LANE0_SET, dp->link.train_set,
>>   					dp->link.cap.lanes);
>>   		if (ret != dp->link.cap.lanes) {
>> @@ -255,6 +273,11 @@ static int hibmc_dp_link_training_channel_eq(struct hibmc_dp_dev *dp)
>>   		}
>>   
>>   		hibmc_dp_link_get_adjust_train(dp, lane_status);
>> +
>> +		ret = hibmc_dp_serdes_set_tx_cfg(dp, dp->link.train_set);
>> +		if (ret)
>> +			return ret;
>> +
>>   		ret = drm_dp_dpcd_write(&dp->aux, DP_TRAINING_LANE0_SET,
>>   					dp->link.train_set, dp->link.cap.lanes);
>>   		if (ret != dp->link.cap.lanes) {
>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h
>> index 4a515c726d52..f2fa9807d8ab 100644
>> --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h
>> +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h
>> @@ -72,5 +72,6 @@
>>   #define HIBMC_DP_CFG_STREAM_TU_SYMBOL_FRAC_SIZE	GENMASK(9, 6)
>>   #define HIBMC_DP_CFG_STREAM_HTOTAL_SIZE		GENMASK(31, 16)
>>   #define HIBMC_DP_CFG_STREAM_HBLANK_SIZE		GENMASK(15, 0)
>> +#define HIBMC_DP_CFG_STREAM_SYNC_CALIBRATION	GENMASK(31, 20)
> Please consider restructuring the header so that it becomes more
> obvious, which register are these masks for.
>
>>   
>>   #endif
>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
>> index e6de6d5edf6b..bade693d9730 100644
>> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
>> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
>> @@ -28,9 +28,7 @@
>>   #include "hibmc_drm_drv.h"
>>   #include "hibmc_drm_regs.h"
>>   
>> -#define HIBMC_DP_HOST_SERDES_CTRL		0x1f001c
>> -#define HIBMC_DP_HOST_SERDES_CTRL_VAL		0x8a00
>> -#define HIBMC_DP_HOST_SERDES_CTRL_MASK		0x7ffff
>> +#define HIBMC_DP_HOST_SERDES_CTRL	0x1f001c
> Unnecessary whitespace change.
>
> Why HIBMC_DP_HOST_SERDES_CTRL is not in the dp_reg.h?
>
>>   
>>   DEFINE_DRM_GEM_FOPS(hibmc_fops);
>>   
>> @@ -122,8 +120,8 @@ static int hibmc_kms_init(struct hibmc_drm_private *priv)
>>   	}
>>   
>>   	/* if DP existed, init DP */
>> -	if ((readl(priv->mmio + HIBMC_DP_HOST_SERDES_CTRL) &
>> -	     HIBMC_DP_HOST_SERDES_CTRL_MASK) == HIBMC_DP_HOST_SERDES_CTRL_VAL) {
>> +	ret = readl(priv->mmio + HIBMC_DP_HOST_SERDES_CTRL);
>> +	if (ret) {
>>   		ret = hibmc_dp_init(priv);
>>   		if (ret)
>>   			drm_err(dev, "failed to init dp: %d\n", ret);
>> -- 
>> 2.33.0
>>