drivers/gpu/drm/hisilicon/hibmc/dp/dp_serdes.c

Source file repositories/reference/linux-study-clean/drivers/gpu/drm/hisilicon/hibmc/dp/dp_serdes.c

File Facts

System
Linux kernel
Corpus path
drivers/gpu/drm/hisilicon/hibmc/dp/dp_serdes.c
Extension
.c
Size
2139 bytes
Lines
72
Domain
Driver Families
Bucket
drivers/gpu
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-or-later
// Copyright (c) 2025 Hisilicon Limited.

#include <linux/delay.h>
#include <drm/drm_device.h>
#include <drm/drm_print.h>
#include "dp_comm.h"
#include "dp_config.h"
#include "dp_reg.h"

int hibmc_dp_serdes_set_tx_cfg(struct hibmc_dp_dev *dp, u8 train_set[HIBMC_DP_LANE_NUM_MAX])
{
	static const u32 serdes_tx_cfg[4][4] = { {DP_SERDES_VOL0_PRE0, DP_SERDES_VOL0_PRE1,
						  DP_SERDES_VOL0_PRE2, DP_SERDES_VOL0_PRE3},
						 {DP_SERDES_VOL1_PRE0, DP_SERDES_VOL1_PRE1,
						  DP_SERDES_VOL1_PRE2}, {DP_SERDES_VOL2_PRE0,
						  DP_SERDES_VOL2_PRE1}, {DP_SERDES_VOL3_PRE0}};
	int cfg[2];
	int i;

	for (i = 0; i < HIBMC_DP_LANE_NUM_MAX; i++) {
		cfg[i] = serdes_tx_cfg[FIELD_GET(DP_TRAIN_VOLTAGE_SWING_MASK, train_set[i])]
				      [FIELD_GET(DP_TRAIN_PRE_EMPHASIS_MASK, train_set[i])];
		if (!cfg[i])
			return -EINVAL;

		/* lane1 offset is 4 */
		writel(FIELD_PREP(HIBMC_DP_PMA_TXDEEMPH, cfg[i]),
		       dp->serdes_base + HIBMC_DP_PMA_LANE0_OFFSET + i * 4);
	}

	usleep_range(300, 500);

	if (readl(dp->serdes_base + HIBMC_DP_LANE_STATUS_OFFSET) != DP_SERDES_DONE) {
		drm_dbg_dp(dp->dev, "dp serdes cfg failed\n");
		return -EAGAIN;
	}

	return 0;
}

int hibmc_dp_serdes_rate_switch(u8 rate, struct hibmc_dp_dev *dp)
{
	writel(rate, dp->serdes_base + HIBMC_DP_LANE0_RATE_OFFSET);
	writel(rate, dp->serdes_base + HIBMC_DP_LANE1_RATE_OFFSET);

	usleep_range(300, 500);

	if (readl(dp->serdes_base + HIBMC_DP_LANE_STATUS_OFFSET) != DP_SERDES_DONE) {
		drm_dbg_dp(dp->dev, "dp serdes rate switching failed\n");
		return -EAGAIN;
	}

	if (rate < DP_SERDES_BW_8_1)
		drm_dbg_dp(dp->dev, "reducing serdes rate to :%d\n",
			   rate ? rate * HIBMC_DP_LINK_RATE_CAL * 10 : 162);

	return 0;
}

int hibmc_dp_serdes_init(struct hibmc_dp_dev *dp)
{
	dp->serdes_base = dp->base + HIBMC_DP_HOST_OFFSET;

	writel(FIELD_PREP(HIBMC_DP_PMA_TXDEEMPH, DP_SERDES_VOL0_PRE0),
	       dp->serdes_base + HIBMC_DP_PMA_LANE0_OFFSET);
	writel(FIELD_PREP(HIBMC_DP_PMA_TXDEEMPH, DP_SERDES_VOL0_PRE0),
	       dp->serdes_base + HIBMC_DP_PMA_LANE1_OFFSET);

	return hibmc_dp_serdes_rate_switch(DP_SERDES_BW_8_1, dp);
}

Annotation

Implementation Notes