[PATCH v1 06/16] drm/i915/bios: parse Snps's VS/PE Override Block #57

["Michał Grzelak" <michal.grzelak@intel.com>]

Parse content of VBT #57 into buffers' table. In case of Snps we can
also parse the content by casting pointer to the memory location.

Parse VBT #57 going row-wise since VBT #57 is a contiguous block.

Reuse LOW() macro for extracting lower byte out of u32 value read from
Block 57.

Equivalently, extraction of lower byte could be done by cast to (u8).
This approach would have the advantage of dropping "drm/i915/buf_trans:
switch from u8 to u32" patch.

Signed-off-by: Michał Grzelak <michal.grzelak@intel.com>
---
 drivers/gpu/drm/i915/display/intel_bios.c | 31 +++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
index 4b2d86bac2de..c09af91ab55f 100644
--- a/drivers/gpu/drm/i915/display/intel_bios.c
+++ b/drivers/gpu/drm/i915/display/intel_bios.c
@@ -2188,6 +2188,33 @@ parse_compression_parameters(struct intel_display *display)
 	}
 }
 
+static void
+parse_vswing_preemph_snps(union intel_ddi_buf_trans_entry **bufs_table,
+			  const struct bdb_vswing_preemph *block)
+{
+	union intel_ddi_buf_trans_entry *entry;
+	const u32 *tables = block->tables;
+	u32 num_rows = 16;
+	size_t offset = 0;
+	size_t row_width;
+	const u32 *vals;
+
+	row_width = block->num_columns * sizeof(*tables);
+
+	for (int idx = 0; idx < block->num_tables; idx++) {
+		for (int row = 0; row < num_rows; row++) {
+			vals = &tables[offset];
+
+			entry = &bufs_table[idx][row];
+			entry->snps.vswing = LOW(vals[0]);
+			entry->snps.pre_cursor = LOW(vals[1]);
+			entry->snps.post_cursor = LOW(vals[2]);
+
+			offset += row_width;
+		}
+	}
+}
+
 static void
 parse_vswing_preemph_lt(union intel_ddi_buf_trans_entry **bufs_table,
 			const struct bdb_vswing_preemph *block)
@@ -2245,6 +2272,10 @@ parse_vswing_preemph_override(struct intel_display *display)
 
 	if (HAS_LT_PHY(display)) {
 		parse_vswing_preemph_lt(bufs_table, block);
+	} else if (DISPLAY_VER(display) >= 14) {
+		parse_vswing_preemph_snps(bufs_table, block);
+	} else if (display->platform.battlemage) {
+		parse_vswing_preemph_snps(bufs_table, block);
 	} else {
 		drm_dbg_kms(display->drm, "Vswing / Preemph Override not yet supported on the platform\n");
 		bufs_table = NULL;
-- 
2.45.2