SCDC provides status information on the current display link. At the very least, it may be useful to expose this info through debugfs.
Add a debugfs entry for it under the connector, which displays a few more details parsed out of the SCDC registers. A new drm_scdc_debugfs_init function can be called by the connector implementation to initialise the debugfs file. Reviewed-by: Daniel Stone <[email protected]> Signed-off-by: Nicolas Frattaroli <[email protected]> --- drivers/gpu/drm/display/drm_scdc_helper.c | 228 ++++++++++++++++++++++++++++++ include/drm/display/drm_scdc_helper.h | 56 ++++++++ 2 files changed, 284 insertions(+) diff --git a/drivers/gpu/drm/display/drm_scdc_helper.c b/drivers/gpu/drm/display/drm_scdc_helper.c index 8403f2390ab6..75a59c6fc7a5 100644 --- a/drivers/gpu/drm/display/drm_scdc_helper.c +++ b/drivers/gpu/drm/display/drm_scdc_helper.c @@ -24,11 +24,14 @@ #include <linux/export.h> #include <linux/i2c.h> #include <linux/slab.h> +#include <linux/debugfs.h> #include <linux/delay.h> +#include <linux/overflow.h> #include <drm/display/drm_scdc_helper.h> #include <drm/drm_connector.h> #include <drm/drm_device.h> +#include <drm/drm_managed.h> #include <drm/drm_print.h> /** @@ -55,6 +58,11 @@ #define SCDC_I2C_SLAVE_ADDRESS 0x54 +struct scdc_debugfs_priv { + struct drm_connector *connector; + struct drm_scdc_state state; +}; + /** * drm_scdc_read - read a block of data from SCDC * @adapter: I2C controller @@ -276,3 +284,223 @@ bool drm_scdc_set_high_tmds_clock_ratio(struct drm_connector *connector, return true; } EXPORT_SYMBOL(drm_scdc_set_high_tmds_clock_ratio); + +/** + * drm_scdc_read_status0_flags - Read SCDC "Status Flags" Register + * @connector: pointer to &struct drm_connector to issue the scdc request on + * @flags: pointer to the caller's &struct drm_scdc_status_flags to output to + * + * Reads the SCDC Status Flags 0 register, and outputs its contents to the + * destination @flags. Contents of @flags.status0 is only valid if function + * returns 0. + * + * Returns: %0 on success, negative errno on error. + */ +int drm_scdc_read_status0_flags(struct drm_connector *connector, + struct drm_scdc_status_flags *flags) +{ + int ret; + + ret = drm_scdc_writeb(connector->ddc, SCDC_UPDATE_0, SCDC_STATUS_UPDATE); + if (ret) + return ret; + + return drm_scdc_readb(connector->ddc, SCDC_STATUS_FLAGS_0, &flags->status0.data); +} +EXPORT_SYMBOL(drm_scdc_read_status0_flags); + +/** + * drm_scdc_read_error_counters - Read and clear SCDC error counters + * @connector: pointer to &struct drm_connector to issue the scdc request on + * @counter: Caller's u16 array with 3 elements to write the counter values into + * + * Read the SCDC channel error counters. If the count of channel *n* is valid, + * write it into counter[n]. Otherwise, set counter[n] to 0. Reads all counters + * in one read chunk, then clears every counter, as is mandated. + * + * Returns: %0 on success, negative errno on error. + */ +int drm_scdc_read_error_counters(struct drm_connector *connector, u16 counter[3]) +{ + u8 buf[7] = { 0 }; + int ret; + u8 sum = 0; + int i; + + ret = drm_scdc_writeb(connector->ddc, SCDC_UPDATE_0, SCDC_CED_UPDATE); + if (ret) + return ret; + + ret = drm_scdc_read(connector->ddc, SCDC_ERR_DET_0_L, buf, ARRAY_SIZE(buf)); + if (ret) + return ret; + + /* + * Verify the "checksum", i.e. sum up everything including the checksum + * register as a wrapping unsigned 8-bit addition and verify it's 0. + */ + for (i = 0; i < ARRAY_SIZE(buf); i++) + sum = wrapping_add(u8, sum, buf[i]); + + if (sum) + return -EPROTO; + + for (i = 0; i < ARRAY_SIZE(buf) - 1; i += 2) { + if (buf[i + 1] & SCDC_CHANNEL_VALID) + counter[i / 2] = buf[i] | (buf[i + 1] & ~SCDC_CHANNEL_VALID) << 8; + else + counter[i / 2] = 0; + + buf[i] = 0; + buf[i + 1] = 0; + } + buf[ARRAY_SIZE(buf) - 1] = 0; + + return drm_scdc_write(connector->ddc, SCDC_ERR_DET_0_L, buf, ARRAY_SIZE(buf)); +} +EXPORT_SYMBOL(drm_scdc_read_error_counters); + +/** + * drm_scdc_read_state - Update state from SCDC + * @connector: pointer to a &struct drm_connector on which to operate on + * @state: pointer to a &struct drm_scdc_state to fill + * + * Reads update flags from SCDC, and updates the parts of @state that SCDC + * claims have changed, as well as populating those where such a distinction + * can't be made. + * + * Returns: %0 on success, negative errno on failure. + */ +int drm_scdc_read_state(struct drm_connector *connector, struct drm_scdc_state *state) +{ + u8 upd_flags[2] = { 0 }; + struct i2c_adapter *ddc; + struct drm_scdc *scdc; + int ret; + u8 val; + + if (!state || !connector) + return -ENODEV; + + scdc = &connector->display_info.hdmi.scdc; + ddc = connector->ddc; + + if (!scdc->supported) + return -EOPNOTSUPP; + + ret = drm_scdc_readb(ddc, SCDC_TMDS_CONFIG, &val); + if (ret) + return ret; + + state->scrambling_enabled = !!(val & SCDC_SCRAMBLING_ENABLE); + state->tmds_bclk_x40 = !!(val & SCDC_TMDS_BIT_CLOCK_RATIO_BY_40); + + state->scrambling_detected = drm_scdc_get_scrambling_status(connector); + + ret = drm_scdc_read(ddc, SCDC_UPDATE_0, &upd_flags, sizeof(upd_flags)); + if (ret) + return ret; + + if (upd_flags[0] & SCDC_STATUS_UPDATE) { + ret = drm_scdc_read_status0_flags(connector, &state->stf); + if (ret) + return ret; + } + + if (upd_flags[0] & SCDC_CED_UPDATE) { + ret = drm_scdc_read_error_counters(connector, state->error_count); + if (ret) + return ret; + } + + return 0; +} +EXPORT_SYMBOL(drm_scdc_read_state); + +#define scdc_print_str(_f, key, s) \ + (seq_printf((_f), "%-30s: %s\n", (key), (s))) +#define scdc_print_flag(_f, key, val) \ + (scdc_print_str((_f), (key), str_yes_no((val)))) +#define scdc_print_dec(_f, key, val) \ + (seq_printf((_f), "%-30s: %d\n", (key), (val))) + +static int scdc_status_show(struct seq_file *m, void *data) +{ + struct scdc_debugfs_priv *priv = m->private; + struct drm_scdc_state *st = &priv->state; + struct drm_connector *connector = priv->connector; + struct drm_scdc *scdc = &connector->display_info.hdmi.scdc; + int ret; + + drm_connector_get(connector); + + if (connector->status != connector_status_connected) { + ret = -ENODEV; + goto err_conn_put; + } + + scdc_print_flag(m, "SCDC Supported", scdc->supported); + if (!scdc->supported) { + ret = 0; + goto err_conn_put; + } + + scdc_print_flag(m, "Sink Read Request Capable", scdc->read_request); + scdc_print_flag(m, "Scrambling Supported", scdc->scrambling.supported); + scdc_print_flag(m, "Low Rate Scrambling Supported", scdc->scrambling.low_rates); + + ret = drm_scdc_read_state(connector, st); + drm_connector_put(connector); + if (ret) + return ret; + + scdc_print_flag(m, "Scrambling Enabled", st->scrambling_enabled); + scdc_print_flag(m, "Scrambling Detected", st->scrambling_detected); + + if (st->tmds_bclk_x40) + scdc_print_str(m, "TMDS Bit Clock Ratio", "1/40"); + else + scdc_print_str(m, "TMDS Bit Clock Ratio", "1/10"); + + scdc_print_flag(m, "Clock Detected", st->stf.status0.flags.clock_detected); + scdc_print_flag(m, "Channel 0 Locked", st->stf.status0.flags.ch0_locked); + scdc_print_flag(m, "Channel 1 Locked", st->stf.status0.flags.ch1_locked); + scdc_print_flag(m, "Channel 2 Locked", st->stf.status0.flags.ch2_locked); + + scdc_print_dec(m, "Channel 0 Errors", st->error_count[0]); + scdc_print_dec(m, "Channel 1 Errors", st->error_count[1]); + scdc_print_dec(m, "Channel 2 Errors", st->error_count[2]); + + return 0; + +err_conn_put: + drm_connector_put(connector); + + return ret; +} +DEFINE_SHOW_ATTRIBUTE(scdc_status); + +/** + * drm_scdc_debugfs_init - Initialize scdc files in connector debugfs + * @connector: pointer to &struct drm_connector to operate on + * @root: debugfs &struct dentry for the debugfs root of @connector + * + * Creates SCDC-related debugfs files for @connector. Must be called after + * @root is already created. + */ +void drm_scdc_debugfs_init(struct drm_connector *connector, struct dentry *root) +{ + struct scdc_debugfs_priv *priv; + + if (!root || !connector) + return; + + priv = drmm_kzalloc(connector->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return; + + priv->connector = connector; + + debugfs_create_file("scdc_status", 0444, root, priv, &scdc_status_fops); +} +EXPORT_SYMBOL(drm_scdc_debugfs_init); diff --git a/include/drm/display/drm_scdc_helper.h b/include/drm/display/drm_scdc_helper.h index e9ccaeba56dd..c066c1158275 100644 --- a/include/drm/display/drm_scdc_helper.h +++ b/include/drm/display/drm_scdc_helper.h @@ -30,6 +30,55 @@ struct drm_connector; struct i2c_adapter; +struct dentry; + +struct drm_scdc_status_flags { + /* Status Register 0 */ + union { + struct { + bool clock_detected : 1; + bool ch0_locked : 1; + bool ch1_locked : 1; + bool ch2_locked : 1; + bool rsvd_4 : 1; + bool rsvd_5 : 1; + bool rsvd_6 : 1; + bool rsvd_7 : 1; + } flags __packed; + u8 data; + } status0; + + /* Status Register 1 */ + union { + struct { + bool rsvd_0 : 1; + bool rsvd_1 : 1; + bool rsvd_2 : 1; + bool rsvd_3 : 1; + bool rsvd_4 : 1; + bool rsvd_5 : 1; + bool rsvd_6 : 1; + bool rsvd_7 : 1; + } flags __packed; + u8 data; + } status1; +}; + +struct drm_scdc_state { + /** @stf: contents of the status flag registers */ + struct drm_scdc_status_flags stf; + /** @scramling_enabled: true if TMDS scrambling is on */ + bool scrambling_enabled; + /** @scrambling_detected: true if the sink actually detected scrambling */ + bool scrambling_detected; + /** + * @tmds_bclk_x40: true if TMDS bit period is 1/40th of the TMDS + * clock period, false if it's 1/10th of the clock period. + */ + bool tmds_bclk_x40; + /** @error_count: character error counts for each channel */ + u16 error_count[3]; +}; int drm_scdc_read(struct i2c_adapter *adapter, u8 offset, void *buffer, size_t size); @@ -77,4 +126,11 @@ bool drm_scdc_get_scrambling_status(struct drm_connector *connector); bool drm_scdc_set_scrambling(struct drm_connector *connector, bool enable); bool drm_scdc_set_high_tmds_clock_ratio(struct drm_connector *connector, bool set); +int drm_scdc_read_status0_flags(struct drm_connector *connector, + struct drm_scdc_status_flags *flags); +int drm_scdc_read_state(struct drm_connector *connector, + struct drm_scdc_state *state); +int drm_scdc_read_error_counters(struct drm_connector *connector, u16 counter[3]); +void drm_scdc_debugfs_init(struct drm_connector *connector, struct dentry *root); + #endif -- 2.54.0
