Re: [PATCH v8 15/19] drm/mediatek: Add mt8195 Embedded DisplayPort driver

Hi, Guillaume:

On Fri, 2022-02-18 at 15:54 +0100, Guillaume Ranquet wrote:

From: Markus Schneider-Pargmann msp@baylibre.com

This patch adds a DisplayPort driver for the Mediatek mt8195 SoC.

It supports the mt8195, the embedded DisplayPort units. It offers hot-plug-detection and DisplayPort 1.4 with up to 4 lanes.

The driver creates a child device for the phy. The child device will never exist without the parent being active. As they are sharing a register range, the parent passes a regmap pointer to the child so that both can work with the same register range. The phy driver sets device data that is read by the parent to get the phy device that can be used to control the phy properties.

This driver is based on an initial version by Jason-JH.Lin jason-jh.lin@mediatek.com.

Signed-off-by: Markus Schneider-Pargmann msp@baylibre.com Signed-off-by: Guillaume Ranquet granquet@baylibre.com Reported-by: kernel test robot lkp@intel.com

---

drivers/gpu/drm/mediatek/Kconfig | 7 + drivers/gpu/drm/mediatek/Makefile | 2 + drivers/gpu/drm/mediatek/mtk_dp.c | 2358 ++++++++++++++++++++++++ drivers/gpu/drm/mediatek/mtk_dp_reg.h | 568 ++++++ drivers/gpu/drm/mediatek/mtk_drm_drv.c | 1 + drivers/gpu/drm/mediatek/mtk_drm_drv.h | 1 + 6 files changed, 2937 insertions(+) create mode 100644 drivers/gpu/drm/mediatek/mtk_dp.c create mode 100644 drivers/gpu/drm/mediatek/mtk_dp_reg.h

[snip]

+struct mtk_dp_train_info {

• bool tps3;
• bool tps4;
• bool sink_ssc;
• bool cable_plugged_in;

Move to external display port patch.

• bool cable_state_change;

Move to external display port patch.

• bool cr_done;
• bool eq_done;
• // link_rate is in multiple of 0.27Gbps
• int link_rate;
• int lane_count;
• int irq_status;

Move to external display port patch.

• int check_cap_count;

+};

[snip]

+// Same values as used for DP Spec MISC0 bits 5,6,7 +enum mtk_dp_color_depth {

• MTK_DP_COLOR_DEPTH_6BIT = 0,
• MTK_DP_COLOR_DEPTH_8BIT = 1,

Only 8bits is used, so drop other definition.

• MTK_DP_COLOR_DEPTH_10BIT = 2,
• MTK_DP_COLOR_DEPTH_12BIT = 3,
• MTK_DP_COLOR_DEPTH_16BIT = 4,
• MTK_DP_COLOR_DEPTH_UNKNOWN = 5,

+};

[snip]

+struct mtk_dp {

• struct device *dev;
• struct platform_device *phy_dev;
• struct phy *phy;
• struct dp_cal_data cal_data;
• struct drm_device *drm_dev;
• struct drm_bridge bridge;
• struct drm_bridge *next_bridge;
• struct drm_dp_aux aux;
• /* Protects edid as it is used in both bridge ops and IRQ

handler */

• struct mutex edid_lock;
• struct edid *edid;
• u8 rx_cap[DP_RECEIVER_CAP_SIZE];
• struct mtk_dp_info info;
• enum mtk_dp_state state;
• struct mtk_dp_train_info train_info;
• enum mtk_dp_train_state train_state;
• unsigned int input_fmt;
• struct regmap *regs;
• struct clk *dp_tx_clk;
• bool enabled;
• bool has_fec;
• /* Protects the mtk_dp struct */
• struct mutex dp_lock;
• hdmi_codec_plugged_cb plugged_cb;
• struct device *codec_dev;
• u8 connector_eld[MAX_ELD_BYTES];

Move this to dp audio patch.

• struct drm_connector *conn;

+};

[snip]

+static void mtk_dp_set_color_format(struct mtk_dp *mtk_dp,

• 		    enum mtk_dp_color_format
  

color_format) +{

• u32 val;
• mtk_dp->info.format = color_format;

When call into this function from mtk_dp_video_config(), it calls

mtk_dp_set_color_format(mtk_dp, mtk_dp->info.format);

It looks weird that you pass mtk_dp->info.format into this function and set it to it. So I would like this function to be pure register setting, and move this variable keeping out of this function.

• // Update MISC0
• mtk_dp_update_bits(mtk_dp, MTK_DP_ENC0_P0_3034,

• 	   color_format << DP_TEST_COLOR_FORMAT_SHIFT,
  

• 	   DP_TEST_COLOR_FORMAT_MASK);
  

• switch (color_format) {
• case MTK_DP_COLOR_FORMAT_YUV_422:

• val = PIXEL_ENCODE_FORMAT_DP_ENC0_P0_YCBCR422;
  

• break;
  

• case MTK_DP_COLOR_FORMAT_YUV_420:

• val = PIXEL_ENCODE_FORMAT_DP_ENC0_P0_YCBCR420;
  

• break;
  

• case MTK_DP_COLOR_FORMAT_YONLY:
• case MTK_DP_COLOR_FORMAT_RAW:
• case MTK_DP_COLOR_FORMAT_RESERVED:
• case MTK_DP_COLOR_FORMAT_UNKNOWN:

• drm_warn(mtk_dp->drm_dev, "Unsupported color format:
  

%d\n",

• 	 color_format);
  

• fallthrough;
  

• case MTK_DP_COLOR_FORMAT_RGB_444:
• case MTK_DP_COLOR_FORMAT_YUV_444:

• val = PIXEL_ENCODE_FORMAT_DP_ENC0_P0_RGB;
  

• break;
  

• }
• mtk_dp_update_bits(mtk_dp, MTK_DP_ENC0_P0_303C, val,

• 	   PIXEL_ENCODE_FORMAT_DP_ENC0_P0_MASK);
  

+}

[snip]

+static void mtk_dp_pg_disable(struct mtk_dp *mtk_dp) +{

• mtk_dp_update_bits(mtk_dp, MTK_DP_ENC0_P0_3038, 0,

• 	   VIDEO_SOURCE_SEL_DP_ENC0_P0_MASK);
  

• mtk_dp_update_bits(mtk_dp, MTK_DP_ENC0_P0_31B0,

• 	   4 << PGEN_PATTERN_SEL_SHIFT,
  

PGEN_PATTERN_SEL_MASK); +}

+static bool mtk_dp_plug_state(struct mtk_dp *mtk_dp)

Move this function to external dp patch.

+{

• return !!(mtk_dp_read(mtk_dp, MTK_DP_TRANS_P0_3414) &

•   HPD_DB_DP_TRANS_P0_MASK);
  

+}

[snip]

+static void mtk_dp_train_set_pattern(struct mtk_dp *mtk_dp, int pattern) +{

• if (pattern < 0 || pattern > 4) {

Never happen, remove this checking.

• drm_err(mtk_dp->drm_dev,
  

• 	"Implementation error, no such pattern %d\n",
  

pattern);

• return;
  

• }
• if (pattern == 1) // TPS1

• mtk_dp_set_idle_pattern(mtk_dp, false);
  

• mtk_dp_update_bits(mtk_dp,

• 	   MTK_DP_TRANS_P0_3400,
  

• 	   pattern ? BIT(pattern - 1) <<
  

PATTERN1_EN_DP_TRANS_P0_SHIFT : 0,

• 	   PATTERN1_EN_DP_TRANS_P0_MASK |
  

PATTERN2_EN_DP_TRANS_P0_MASK |

• 	   PATTERN3_EN_DP_TRANS_P0_MASK |
  

• 	   PATTERN4_EN_DP_TRANS_P0_MASK);
  

+}

[snip]

+static void mtk_dp_setup_tu(struct mtk_dp *mtk_dp) +{

• u32 sram_read_start = MTK_DP_TBC_BUF_READ_START_ADDR;

It's not necessary to have a initial value.

• if (mtk_dp->train_info.lane_count > 0) {

• sram_read_start = min_t(u32,
  

• 			MTK_DP_TBC_BUF_READ_START_ADDR,
  

• 			mtk_dp->info.timings.vm.hactive 
  

/

• 			(mtk_dp->train_info.lane_count
  

• 4 * 2 * 2));

• mtk_dp_set_sram_read_start(mtk_dp, sram_read_start);
  

• }
• mtk_dp_setup_encoder(mtk_dp);

+}

[snip]

+static void mtk_dp_train_handler(struct mtk_dp *mtk_dp) +{

• int ret = 0;
• int i = 50;
• do {

• if (mtk_dp->train_state == MTK_DP_TRAIN_STATE_NORMAL)
  

• 	continue;
  

• switch (mtk_dp->train_state) {
  

• case MTK_DP_TRAIN_STATE_STARTUP:
  

• 	mtk_dp->train_state =
  

MTK_DP_TRAIN_STATE_CHECKCAP;

• 	break;
  

• case MTK_DP_TRAIN_STATE_CHECKCAP:
  

• 	if (mtk_dp_parse_capabilities(mtk_dp)) {
  

• 		mtk_dp->train_info.check_cap_count = 0;
  

• 		mtk_dp->train_state =
  

MTK_DP_TRAIN_STATE_CHECKEDID;

• 	} else {
  

• 		mtk_dp->train_info.check_cap_count++;
  

• 		if (mtk_dp->train_info.check_cap_count
  

...

• 			MTK_DP_CHECK_SINK_CAP_TIMEOUT_C
  

OUNT) {

• 			mtk_dp-
  

...

train_info.check_cap_count = 0;

• 			mtk_dp->train_state =
  

MTK_DP_TRAIN_STATE_DPIDLE;

• 			ret = -ETIMEDOUT;
  

• 		}
  

• 	}
  

• 	break;
  

• case MTK_DP_TRAIN_STATE_CHECKEDID:
  

• 	mtk_dp->train_state =
  

MTK_DP_TRAIN_STATE_TRAINING_PRE;

• 	break;
  

• case MTK_DP_TRAIN_STATE_TRAINING_PRE:
  

• 	mtk_dp->train_state =
  

MTK_DP_TRAIN_STATE_TRAINING;

• 	break;
  

• case MTK_DP_TRAIN_STATE_TRAINING:
  

• 	ret = mtk_dp_train_start(mtk_dp);
  

• 	if (!ret) {
  

• 		mtk_dp_video_mute(mtk_dp, true);
  

• 		mtk_dp->train_state =
  

MTK_DP_TRAIN_STATE_NORMAL;

• 		mtk_dp_fec_enable(mtk_dp, mtk_dp-
  

...

has_fec);

• 	} else if (ret != -EAGAIN) {
  

• 		mtk_dp->train_state =
  

MTK_DP_TRAIN_STATE_DPIDLE;

• 	}
  

• 	ret = 0;
  

• 	break;
  

• case MTK_DP_TRAIN_STATE_NORMAL:
  

• 	break;
  

• case MTK_DP_TRAIN_STATE_DPIDLE:
  

• 	break;
  

• default:
  

You have list all 7 states, why need default?

• 	break;
  

• }
  

• } while (ret && i--);

Why keep in this loop while error happen?

• if (ret)

• drm_err(mtk_dp->drm_dev, "Train handler failed %d\n",
  

ret); +}

[snip]

+static void mtk_dp_state_handler(struct mtk_dp *mtk_dp) +{

• switch (mtk_dp->state) {
• case MTK_DP_STATE_INITIAL:

• mtk_dp_video_mute(mtk_dp, true);
  

• mtk_dp->state = MTK_DP_STATE_IDLE;
  

• break;
  

• case MTK_DP_STATE_IDLE:

• if (mtk_dp->train_state == MTK_DP_TRAIN_STATE_NORMAL)
  

• 	mtk_dp->state = MTK_DP_STATE_PREPARE;
  

• break;
  

• case MTK_DP_STATE_PREPARE:

• mtk_dp_video_config(mtk_dp);
  

• mtk_dp_video_enable(mtk_dp, true);
  

• mtk_dp->state = MTK_DP_STATE_NORMAL;
  

• break;
  

• case MTK_DP_STATE_NORMAL:

• if (mtk_dp->train_state != MTK_DP_TRAIN_STATE_NORMAL) {
  

• 	mtk_dp_video_mute(mtk_dp, true);
  

• 	mtk_dp->state = MTK_DP_STATE_IDLE;
  

• }
  

• break;
  

• default:

There is no default case, so remove this.

• break;
  

• }

+}

[snip]

+static struct edid *mtk_dp_get_edid(struct drm_bridge *bridge,

• 		    struct drm_connector *connector)
  

+{

• struct mtk_dp *mtk_dp = mtk_dp_from_bridge(bridge);
• bool enabled = mtk_dp->enabled;
• struct edid *new_edid = NULL;
• if (!enabled)

Would DRM core make this happen?

• drm_bridge_chain_pre_enable(bridge);
  

• drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER,

DP_SET_POWER_D0);

• usleep_range(2000, 5000);
• if (mtk_dp_plug_state(mtk_dp))

• new_edid = drm_get_edid(connector, &mtk_dp->aux.ddc);
  

• if (!enabled)

• drm_bridge_chain_post_disable(bridge);
  

• mutex_lock(&mtk_dp->edid_lock);
• kfree(mtk_dp->edid);
• mtk_dp->edid = NULL;
• if (!new_edid) {

• mutex_unlock(&mtk_dp->edid_lock);
  

• return NULL;
  

• }
• mtk_dp->edid = drm_edid_duplicate(new_edid);
• mutex_unlock(&mtk_dp->edid_lock);
• return new_edid;

+}

[snip]

+static void mtk_dp_bridge_atomic_enable(struct drm_bridge *bridge,

• 			struct drm_bridge_state
  

*old_state) +{

• struct mtk_dp *mtk_dp = mtk_dp_from_bridge(bridge);
• struct drm_connector_state *conn_state;
• struct drm_crtc *crtc;
• struct drm_crtc_state *crtc_state;
• mtk_dp->conn =

drm_atomic_get_new_connector_for_encoder(old_state->base.state,

• 						bridge-
  

...

encoder);

• if (!mtk_dp->conn) {

• drm_err(mtk_dp->drm_dev,
  

• 	"Can't enable bridge as connector is
  

missing\n");

• return;
  

• }
• memcpy(mtk_dp->connector_eld, mtk_dp->conn->eld,

MAX_ELD_BYTES);

• conn_state =

• drm_atomic_get_new_connector_state(old_state-
  

...

base.state, mtk_dp->conn);

• if (!conn_state) {

• drm_err(mtk_dp->drm_dev,
  

• 	"Can't enable bridge as connector state is
  

missing\n");

• return;
  

• }
• crtc = conn_state->crtc;
• if (!crtc) {

• drm_err(mtk_dp->drm_dev,
  

• 	"Can't enable bridge as connector state doesn't
  

have a crtc\n");

• return;
  

• }
• crtc_state = drm_atomic_get_new_crtc_state(old_state-

...

base.state, crtc);

• if (!crtc_state) {

• drm_err(mtk_dp->drm_dev,
  

• 	"Can't enable bridge as crtc state is
  

missing\n");

• return;
  

• }
• mtk_dp_parse_drm_mode_timings(mtk_dp, &crtc_state-

...

adjusted_mode);

I think this bridge should implement mode_set() and these code is moved to mode_set().

Regards, CK

• if (!mtk_dp_parse_capabilities(mtk_dp)) {

• drm_err(mtk_dp->drm_dev,
  

• 	"Can't enable bridge as nothing is plugged
  

in\n");

• return;
  

• }
• /* Training */
• mtk_dp_train_handler(mtk_dp);
• mtk_dp_state_handler(mtk_dp);
• mtk_dp->enabled = true;

+}