edid: Add a function to read detailed monitor timings
For digital displays (such as EDP LCDs) we would like to read the EDID information and use that to set display timings. Provide a function to do this. Signed-off-by: Simon Glass <sjg@chromium.org> Signed-off-by: Tom Warren <twarren@nvidia.com>utp
Simon Glass
Tom Warren
parent
490f5fd238
commit
00cf1167bb
105
common/edid.c
105
common/edid.c
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@ -13,6 +13,7 @@
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#include <common.h>
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#include <edid.h>
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#include <errno.h>
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#include <fdtdec.h>
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#include <linux/ctype.h>
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#include <linux/string.h>
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@ -65,6 +66,110 @@ int edid_get_ranges(struct edid1_info *edid, unsigned int *hmin,
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return -1;
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}
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/* Set all parts of a timing entry to the same value */
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static void set_entry(struct timing_entry *entry, u32 value)
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{
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entry->min = value;
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entry->typ = value;
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entry->max = value;
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}
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/**
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* decode_timing() - Decoding an 18-byte detailed timing record
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*
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* @buf: Pointer to EDID detailed timing record
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* @timing: Place to put timing
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*/
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static void decode_timing(u8 *buf, struct display_timing *timing)
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{
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uint x_mm, y_mm;
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unsigned int ha, hbl, hso, hspw, hborder;
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unsigned int va, vbl, vso, vspw, vborder;
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/* Edid contains pixel clock in terms of 10KHz */
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set_entry(&timing->pixelclock, (buf[0] + (buf[1] << 8)) * 10000);
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x_mm = (buf[12] + ((buf[14] & 0xf0) << 4));
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y_mm = (buf[13] + ((buf[14] & 0x0f) << 8));
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ha = (buf[2] + ((buf[4] & 0xf0) << 4));
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hbl = (buf[3] + ((buf[4] & 0x0f) << 8));
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hso = (buf[8] + ((buf[11] & 0xc0) << 2));
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hspw = (buf[9] + ((buf[11] & 0x30) << 4));
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hborder = buf[15];
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va = (buf[5] + ((buf[7] & 0xf0) << 4));
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vbl = (buf[6] + ((buf[7] & 0x0f) << 8));
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vso = ((buf[10] >> 4) + ((buf[11] & 0x0c) << 2));
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vspw = ((buf[10] & 0x0f) + ((buf[11] & 0x03) << 4));
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vborder = buf[16];
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set_entry(&timing->hactive, ha);
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set_entry(&timing->hfront_porch, hso);
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set_entry(&timing->hback_porch, hbl - hso - hspw);
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set_entry(&timing->hsync_len, hspw);
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set_entry(&timing->vactive, va);
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set_entry(&timing->vfront_porch, vso);
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set_entry(&timing->vback_porch, vbl - vso - vspw);
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set_entry(&timing->vsync_len, vspw);
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debug("Detailed mode clock %u Hz, %d mm x %d mm\n"
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" %04x %04x %04x %04x hborder %x\n"
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" %04x %04x %04x %04x vborder %x\n",
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timing->pixelclock.typ,
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x_mm, y_mm,
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ha, ha + hso, ha + hso + hspw,
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ha + hbl, hborder,
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va, va + vso, va + vso + vspw,
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va + vbl, vborder);
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}
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int edid_get_timing(u8 *buf, int buf_size, struct display_timing *timing,
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int *panel_bits_per_colourp)
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{
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struct edid1_info *edid = (struct edid1_info *)buf;
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bool timing_done;
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int i;
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if (buf_size < sizeof(*edid) || edid_check_info(edid)) {
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debug("%s: Invalid buffer\n", __func__);
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return -EINVAL;
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}
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if (!EDID1_INFO_FEATURE_PREFERRED_TIMING_MODE(*edid)) {
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debug("%s: No preferred timing\n", __func__);
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return -ENOENT;
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}
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/* Look for detailed timing */
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timing_done = false;
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for (i = 0; i < 4; i++) {
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struct edid_monitor_descriptor *desc;
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desc = &edid->monitor_details.descriptor[i];
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if (desc->zero_flag_1 != 0) {
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decode_timing((u8 *)desc, timing);
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timing_done = true;
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break;
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}
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}
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if (!timing_done)
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return -EINVAL;
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if (!EDID1_INFO_VIDEO_INPUT_DIGITAL(*edid)) {
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debug("%s: Not a digital display\n", __func__);
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return -ENOSYS;
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}
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if (edid->version != 1 || edid->revision < 4) {
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debug("%s: EDID version %d.%d does not have required info\n",
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__func__, edid->version, edid->revision);
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*panel_bits_per_colourp = -1;
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} else {
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*panel_bits_per_colourp =
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((edid->video_input_definition & 0x70) >> 3) + 4;
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}
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return 0;
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}
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/**
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* Snip the tailing whitespace/return of a string.
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*
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@ -15,6 +15,9 @@
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#include <linux/types.h>
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/* Size of the EDID data */
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#define EDID_SIZE 128
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#define GET_BIT(_x, _pos) \
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(((_x) >> (_pos)) & 1)
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#define GET_BITS(_x, _pos_msb, _pos_lsb) \
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@ -287,4 +290,20 @@ int edid_get_ranges(struct edid1_info *edid, unsigned int *hmin,
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unsigned int *hmax, unsigned int *vmin,
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unsigned int *vmax);
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struct display_timing;
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/**
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* edid_get_timing() - Get basic digital display parameters
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*
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* @param buf Buffer containing EDID data
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* @param buf_size Size of buffer in bytes
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* @param timing Place to put preferring timing information
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* @param panel_bits_per_colourp Place to put the number of bits per
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* colour supported by the panel. This will be set to
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* -1 if not available
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* @return 0 if timings are OK, -ve on error
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*/
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int edid_get_timing(u8 *buf, int buf_size, struct display_timing *timing,
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int *panel_bits_per_colourp);
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#endif /* __EDID_H_ */
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