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-rw-r--r--src/vendorcode/amd/fsp/picasso/platform_descriptors.h26
1 files changed, 26 insertions, 0 deletions
diff --git a/src/vendorcode/amd/fsp/picasso/platform_descriptors.h b/src/vendorcode/amd/fsp/picasso/platform_descriptors.h
index 2faa0abe97..9c0e3e93ac 100644
--- a/src/vendorcode/amd/fsp/picasso/platform_descriptors.h
+++ b/src/vendorcode/amd/fsp/picasso/platform_descriptors.h
@@ -113,6 +113,32 @@ typedef struct __packed {
* Picasso DXIO Descriptor: Used for assigning lanes to PCIe/SATA/XGBE engines, configure
* bifurcation and other settings. Beware that the lane numbers in here are the logical and not
* the physical lane numbers!
+ *
+ * Picasso DXIO lane mapping:
+ *
+ * physical | logical | protocol
+ * ---------|---------|-----------
+ * GFX[7:0] | [15:8] | PCIe
+ * GPP[3:0] | [7:4] | PCIe
+ * GPP[5:4] | [1:0] | PCIe, XGBE
+ * GPP[7:6] | [3:2] | PCIe, SATA
+ *
+ * Dali has less DXIO connectivity than Picasso:
+ *
+ * physical | logical | protocol
+ * ---------|---------|-----------
+ * GFX[3:0] | [11:8] | PCIe
+ * GPP[1:0] | [5:4] | PCIe
+ * GPP[5:4] | [1:0] | PCIe, XGBE
+ * GPP[7:6] | [3:2] | SATA
+ *
+ * Pollock has even less DXIO lanes and the mapping of GPP lane numbers to the logical lane
+ * numbers differs to Picasso/Dali:
+ *
+ * physical | logical | protocol
+ * ---------|---------|----------
+ * GPP[1:0] | [1:0] | PCIe
+ * GPP[3:2] | [5:4] | PCIe
*/
typedef struct __packed {
uint8_t engine_type;