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authorSimon Glass <sjg@chromium.org>2015-04-14 21:03:37 -0600
committerTom Warren <twarren@nvidia.com>2015-05-13 09:24:10 -0700
commit00cf1167bb8f7c08825262ee83e77274ff034f0a (patch)
tree154757d0104c31f3aad7279d29dab862ec305e1e /common/edid.c
parent490f5fd2388f0f7f18e1df22ff318393f8483ea4 (diff)
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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>
Diffstat (limited to 'common/edid.c')
-rw-r--r--common/edid.c105
1 files changed, 105 insertions, 0 deletions
diff --git a/common/edid.c b/common/edid.c
index df797fc..e08e420 100644
--- a/common/edid.c
+++ b/common/edid.c
@@ -13,6 +13,7 @@
#include <common.h>
#include <edid.h>
#include <errno.h>
+#include <fdtdec.h>
#include <linux/ctype.h>
#include <linux/string.h>
@@ -65,6 +66,110 @@ int edid_get_ranges(struct edid1_info *edid, unsigned int *hmin,
return -1;
}
+/* Set all parts of a timing entry to the same value */
+static void set_entry(struct timing_entry *entry, u32 value)
+{
+ entry->min = value;
+ entry->typ = value;
+ entry->max = value;
+}
+
+/**
+ * decode_timing() - Decoding an 18-byte detailed timing record
+ *
+ * @buf: Pointer to EDID detailed timing record
+ * @timing: Place to put timing
+ */
+static void decode_timing(u8 *buf, struct display_timing *timing)
+{
+ uint x_mm, y_mm;
+ unsigned int ha, hbl, hso, hspw, hborder;
+ unsigned int va, vbl, vso, vspw, vborder;
+
+ /* Edid contains pixel clock in terms of 10KHz */
+ set_entry(&timing->pixelclock, (buf[0] + (buf[1] << 8)) * 10000);
+ x_mm = (buf[12] + ((buf[14] & 0xf0) << 4));
+ y_mm = (buf[13] + ((buf[14] & 0x0f) << 8));
+ ha = (buf[2] + ((buf[4] & 0xf0) << 4));
+ hbl = (buf[3] + ((buf[4] & 0x0f) << 8));
+ hso = (buf[8] + ((buf[11] & 0xc0) << 2));
+ hspw = (buf[9] + ((buf[11] & 0x30) << 4));
+ hborder = buf[15];
+ va = (buf[5] + ((buf[7] & 0xf0) << 4));
+ vbl = (buf[6] + ((buf[7] & 0x0f) << 8));
+ vso = ((buf[10] >> 4) + ((buf[11] & 0x0c) << 2));
+ vspw = ((buf[10] & 0x0f) + ((buf[11] & 0x03) << 4));
+ vborder = buf[16];
+
+ set_entry(&timing->hactive, ha);
+ set_entry(&timing->hfront_porch, hso);
+ set_entry(&timing->hback_porch, hbl - hso - hspw);
+ set_entry(&timing->hsync_len, hspw);
+
+ set_entry(&timing->vactive, va);
+ set_entry(&timing->vfront_porch, vso);
+ set_entry(&timing->vback_porch, vbl - vso - vspw);
+ set_entry(&timing->vsync_len, vspw);
+
+ debug("Detailed mode clock %u Hz, %d mm x %d mm\n"
+ " %04x %04x %04x %04x hborder %x\n"
+ " %04x %04x %04x %04x vborder %x\n",
+ timing->pixelclock.typ,
+ x_mm, y_mm,
+ ha, ha + hso, ha + hso + hspw,
+ ha + hbl, hborder,
+ va, va + vso, va + vso + vspw,
+ va + vbl, vborder);
+}
+
+int edid_get_timing(u8 *buf, int buf_size, struct display_timing *timing,
+ int *panel_bits_per_colourp)
+{
+ struct edid1_info *edid = (struct edid1_info *)buf;
+ bool timing_done;
+ int i;
+
+ if (buf_size < sizeof(*edid) || edid_check_info(edid)) {
+ debug("%s: Invalid buffer\n", __func__);
+ return -EINVAL;
+ }
+
+ if (!EDID1_INFO_FEATURE_PREFERRED_TIMING_MODE(*edid)) {
+ debug("%s: No preferred timing\n", __func__);
+ return -ENOENT;
+ }
+
+ /* Look for detailed timing */
+ timing_done = false;
+ for (i = 0; i < 4; i++) {
+ struct edid_monitor_descriptor *desc;
+
+ desc = &edid->monitor_details.descriptor[i];
+ if (desc->zero_flag_1 != 0) {
+ decode_timing((u8 *)desc, timing);
+ timing_done = true;
+ break;
+ }
+ }
+ if (!timing_done)
+ return -EINVAL;
+
+ if (!EDID1_INFO_VIDEO_INPUT_DIGITAL(*edid)) {
+ debug("%s: Not a digital display\n", __func__);
+ return -ENOSYS;
+ }
+ if (edid->version != 1 || edid->revision < 4) {
+ debug("%s: EDID version %d.%d does not have required info\n",
+ __func__, edid->version, edid->revision);
+ *panel_bits_per_colourp = -1;
+ } else {
+ *panel_bits_per_colourp =
+ ((edid->video_input_definition & 0x70) >> 3) + 4;
+ }
+
+ return 0;
+}
+
/**
* Snip the tailing whitespace/return of a string.
*