[Intel-gfx] [PATCH 08/11] drm/i915/bios: Generate LFP data table pointers if the VBT lacks them

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

Modern VBTs (seem at least on TGL with VBT version 240) no
longer contain the LFP data table pointers block (42). We
are expecting to have one in order to be able to parse the
LFP data block (41), so let's make one up.

Since the fp_timing table has variable size we must somehow
determine its size. Rather than just hardcode it we look for
the terminator bytes (0xffff) to figure out where each table
entry starts. dvo_timing, panel_pnp_id, and panel_name are
expected to have fixed size.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_bios.c | 133 +++++++++++++++++++++-
 1 file changed, 132 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
index 7633933a4920..b34f8a77712a 100644
--- a/drivers/gpu/drm/i915/display/intel_bios.c
+++ b/drivers/gpu/drm/i915/display/intel_bios.c
@@ -272,12 +272,132 @@ static bool fixup_lfp_data_ptrs(const void *bdb, void *ptrs_block)
 	return validate_lfp_data_ptrs(bdb, ptrs);
 }
 
+static const void *find_fp_timing_terminator(const u8 *data, int size)
+{
+	int i;
+
+	if (!data)
+		return NULL;
+
+	for (i = 0; i < size - 1; i++) {
+		if (data[i] == 0xff && data[i+1] == 0xff)
+			return &data[i];
+	}
+
+	return NULL;
+}
+
+static int make_lfp_data_ptr(struct lvds_lfp_data_ptr_table *table,
+			     int table_size, int total_size)
+{
+	if (total_size < table_size)
+		return total_size;
+
+	table->table_size = table_size;
+	table->offset = total_size - table_size;
+
+	return total_size - table_size;
+}
+
+static void next_lfp_data_ptr(struct lvds_lfp_data_ptr_table *next,
+			      const struct lvds_lfp_data_ptr_table *prev,
+			      int size)
+{
+	next->table_size = prev->table_size;
+	next->offset = prev->offset + size;
+}
+
+static void *generate_lfp_data_ptrs(const void *bdb)
+{
+	int i, size, table_size, block_size, offset;
+	const void *t0, *t1, *block;
+	struct bdb_lvds_lfp_data_ptrs *ptrs;
+	void *ptrs_block;
+
+	block = find_raw_section(bdb, BDB_LVDS_LFP_DATA);
+	if (!block)
+		return NULL;
+
+	block_size = get_blocksize(block);
+
+	size = block_size;
+	t0 = find_fp_timing_terminator(block, size);
+
+	size -= t0 - block - 2;
+	t1 = find_fp_timing_terminator(t0 + 2, size);
+
+	if (!t0 || !t1)
+		return NULL;
+
+	size = t1 - t0;
+	if (size * 16 > block_size)
+		return NULL;
+
+	ptrs_block = kzalloc(sizeof(*ptrs) + 3, GFP_KERNEL);
+	if (!ptrs_block)
+		return NULL;
+
+	*(u8 *)(ptrs_block + 0) = BDB_LVDS_LFP_DATA_PTRS;
+	*(u16 *)(ptrs_block + 1) = sizeof(*ptrs);
+	ptrs = ptrs_block + 3;
+
+	table_size = sizeof(struct lvds_pnp_id);
+	size = make_lfp_data_ptr(&ptrs->ptr[0].panel_pnp_id, table_size, size);
+
+	table_size = sizeof(struct lvds_dvo_timing);
+	size = make_lfp_data_ptr(&ptrs->ptr[0].dvo_timing, table_size, size);
+
+	table_size = t0 - block + 2;
+	size = make_lfp_data_ptr(&ptrs->ptr[0].fp_timing, table_size, size);
+
+	if (ptrs->ptr[0].fp_timing.table_size)
+		ptrs->lvds_entries++;
+	if (ptrs->ptr[0].dvo_timing.table_size)
+		ptrs->lvds_entries++;
+	if (ptrs->ptr[0].panel_pnp_id.table_size)
+		ptrs->lvds_entries++;
+
+	if (size != 0 || ptrs->lvds_entries != 3) {
+		kfree(ptrs);
+		return NULL;
+	}
+
+	size = t1 - t0;
+	for (i = 1; i < 16; i++) {
+		next_lfp_data_ptr(&ptrs->ptr[i].fp_timing, &ptrs->ptr[i-1].fp_timing, size);
+		next_lfp_data_ptr(&ptrs->ptr[i].dvo_timing, &ptrs->ptr[i-1].dvo_timing, size);
+		next_lfp_data_ptr(&ptrs->ptr[i].panel_pnp_id, &ptrs->ptr[i-1].panel_pnp_id, size);
+	}
+
+	size = t1 - t0;
+	table_size = sizeof(struct lvds_lfp_panel_name);
+
+	if (16 * (size + table_size) <= block_size) {
+		ptrs->panel_name.table_size = table_size;
+		ptrs->panel_name.offset = size * 16;
+	}
+
+	offset = block - bdb;
+
+	for (i = 0; i < 16; i++) {
+		ptrs->ptr[i].fp_timing.offset += offset;
+		ptrs->ptr[i].dvo_timing.offset += offset;
+		ptrs->ptr[i].panel_pnp_id.offset += offset;
+	}
+
+	if (ptrs->panel_name.table_size)
+		ptrs->panel_name.offset += offset;
+
+	return ptrs;
+}
+
 static const void *
 find_section(struct drm_i915_private *i915,
 	     const void *bdb, enum bdb_block_id section_id,
 	     size_t min_size)
 {
 	struct bdb_block_entry *entry;
+	void *temp_block = NULL;
 	const void *block;
 	size_t block_size;
 
@@ -291,6 +411,13 @@ find_section(struct drm_i915_private *i915,
 	}
 
 	block = find_raw_section(bdb, section_id);
+
+	/* Modern VBTs (~TGL+) lack the LFP data table pointers block, make one up */
+	if (!block && section_id == BDB_LVDS_LFP_DATA_PTRS) {
+		drm_dbg_kms(&i915->drm, "Generating LFP data table pointers\n");
+		temp_block = generate_lfp_data_ptrs(bdb);
+		block = temp_block;
+	}
 	if (!block)
 		return NULL;
 
@@ -298,13 +425,17 @@ find_section(struct drm_i915_private *i915,
 
 	entry = kzalloc(struct_size(entry, data, max(min_size, block_size) + 3),
 			GFP_KERNEL);
-	if (!entry)
+	if (!entry) {
+		kfree(temp_block);
 		return NULL;
+	}
 
 	entry->section_id = section_id;
 	entry->min_size = min_size;
 	memcpy(entry->data, block - 3, block_size + 3);
 
+	kfree(temp_block);
+
 	drm_dbg_kms(&i915->drm, "Found BDB block %d (size %zu, min size %zu)\n",
 		    section_id, block_size, min_size);
 
-- 
2.34.1