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lib: add code to control a data source via EDID RAM

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Steve Markgraf 2024-12-12 00:18:11 +01:00
parent 6c033c60b6
commit 9b910ef0a7
2 changed files with 47 additions and 0 deletions
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12
include/hsdaoh.h
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@ -130,6 +130,18 @@ HSDAOH_API int hsdaoh_start_stream(hsdaoh_dev_t *dev,
*/ */
HSDAOH_API int hsdaoh_stop_stream(hsdaoh_dev_t *dev); HSDAOH_API int hsdaoh_stop_stream(hsdaoh_dev_t *dev);
/*!
* Write a datagram to the EDID RAM to control a downstream data source.
* A header with a sequence number and length is prepended to the mesage
* by the library.
*
* \param dev the device handle given by hsdaoh_open()
* \param data pointer to the datagram
* \param len length of the datagram, must not exceed 256-2 = 254 bytes
* due to the prepended header.
* \return 0 on success
*/
HSDAOH_API int hsdaoh_write_edid_cmd_data(hsdaoh_dev_t *dev, uint8_t *data, uint8_t len);
#ifdef __cplusplus #ifdef __cplusplus
} }
#endif #endif

35
src/libhsdaoh.c
View file

@ -84,6 +84,7 @@ struct hsdaoh_dev {
int hid_interface; int hid_interface;
uint8_t edid_seq_cnt;
int frames_since_error; int frames_since_error;
int discard_start_frames; int discard_start_frames;
uint16_t last_frame_cnt; uint16_t last_frame_cnt;
@ -181,6 +182,40 @@ int hsdaoh_read_register(hsdaoh_dev_t *dev, uint16_t addr, uint8_t *val)
return r; return r;
} }
/* Write a datagram to the EDID RAM to control a downstream data source */
int hsdaoh_write_edid_cmd_data(hsdaoh_dev_t *dev, uint8_t *data, uint8_t len)
{
if (!dev || !data || (len > 254))
return -1;
/* increment sequence counter and avoid values 0x00 and 0xff */
dev->edid_seq_cnt++;
if (!dev->edid_seq_cnt || (dev->edid_seq_cnt == 0xff))
dev->edid_seq_cnt = 1;
/* disable I2C access to EDID RAM, reading via I2C will result in a NAK */
hsdaoh_ms_write_register(dev, 0xf063, 0x00);
/* switch EDID RAM to 8051 */
hsdaoh_ms_write_register(dev, 0xf062, 0x80);
/* store header with sequence counter and length of data */
hsdaoh_ms_write_register(dev, 0xf900, dev->edid_seq_cnt);
hsdaoh_ms_write_register(dev, 0xf901, len);
/* store actual data to the EDID RAM */
for (uint8_t i = 0; i < len; i++)
hsdaoh_ms_write_register(dev, 0xf902 + i, data[i]);
/* switch EDID RAM to DDC I2C slave */
hsdaoh_ms_write_register(dev, 0xf062, 0x00);
/* re-enable I2C access to EDID RAM */
hsdaoh_ms_write_register(dev, 0xf063, 0x08);
return 0;
}
/* Switch the MS2130 to a transparent mode, YUYV data received via HDMI /* Switch the MS2130 to a transparent mode, YUYV data received via HDMI
* will be passed through unmodified */ * will be passed through unmodified */
void hsdaoh_ms_enable_transparent_mode(hsdaoh_dev_t *dev) void hsdaoh_ms_enable_transparent_mode(hsdaoh_dev_t *dev)