1 files changed, 19 insertions, 14 deletions

diff --git a/src/intel/common/gen_device_info.c b/src/intel/common/gen_device_info.c
index 30df0b27dc1..1dc17690dc1 100644
--- a/src/intel/common/gen_device_info.c
+++ b/src/intel/common/gen_device_info.c
@@ -335,7 +335,6 @@ static const struct gen_device_info gen_device_info_chv = {
    .max_gs_threads = 336,                           \
    .max_tcs_threads = 336,                          \
    .max_tes_threads = 336,                          \
-   .max_wm_threads = 64 * 9,                        \
    .max_cs_threads = 56,                            \
    .urb = {                                         \
       .size = 384,                                  \
@@ -388,7 +387,6 @@ static const struct gen_device_info gen_device_info_bxt = {
    .max_tcs_threads = 112,
    .max_tes_threads = 112,
    .max_gs_threads = 112,
-   .max_wm_threads = 64 * 3,
    .max_cs_threads = 6 * 6,
    .urb = {
       .size = 192,
@@ -411,7 +409,6 @@ static const struct gen_device_info gen_device_info_bxt_2x6 = {
    .max_tcs_threads = 56, /* XXX: guess */
    .max_tes_threads = 56,
    .max_gs_threads = 56,
-   .max_wm_threads = 64 * 2,
    .max_cs_threads = 6 * 6,
    .urb = {
       .size = 128,
@@ -427,18 +424,11 @@ static const struct gen_device_info gen_device_info_bxt_2x6 = {
  * There's no KBL entry. Using the default SKL (GEN9) GS entries value.
  */
 
-/*
- * Both SKL and KBL support a maximum of 64 threads per
- * Pixel Shader Dispatch (PSD) unit.
- */
-#define  KBL_MAX_THREADS_PER_PSD 64
-
 static const struct gen_device_info gen_device_info_kbl_gt1 = {
    GEN9_FEATURES,
    .gt = 1,
 
    .max_cs_threads = 7 * 6,
-   .max_wm_threads = KBL_MAX_THREADS_PER_PSD * 2,
    .urb.size = 192,
    .num_slices = 1,
 };
@@ -448,7 +438,6 @@ static const struct gen_device_info gen_device_info_kbl_gt1_5 = {
    .gt = 1,
 
    .max_cs_threads = 7 * 6,
-   .max_wm_threads = KBL_MAX_THREADS_PER_PSD * 3,
    .num_slices = 1,
 };
 
@@ -456,7 +445,6 @@ static const struct gen_device_info gen_device_info_kbl_gt2 = {
    GEN9_FEATURES,
    .gt = 2,
 
-   .max_wm_threads = KBL_MAX_THREADS_PER_PSD * 3,
    .num_slices = 1,
 };
 
@@ -464,7 +452,6 @@ static const struct gen_device_info gen_device_info_kbl_gt3 = {
    GEN9_FEATURES,
    .gt = 3,
 
-   .max_wm_threads = KBL_MAX_THREADS_PER_PSD * 6,
    .num_slices = 2,
 };
 
@@ -472,7 +459,6 @@ static const struct gen_device_info gen_device_info_kbl_gt4 = {
    GEN9_FEATURES,
    .gt = 4,
 
-   .max_wm_threads = KBL_MAX_THREADS_PER_PSD * 9,
    /*
     * From the "L3 Allocation and Programming" documentation:
     *
@@ -500,6 +486,25 @@ gen_get_device_info(int devid, struct gen_device_info *devinfo)
       return false;
    }
 
+   /* From the Skylake PRM, 3DSTATE_PS::Scratch Space Base Pointer:
+    *
+    * "Scratch Space per slice is computed based on 4 sub-slices.  SW must
+    *  allocate scratch space enough so that each slice has 4 slices allowed."
+    *
+    * The equivalent internal documentation says that this programming note
+    * applies to all Gen9+ platforms.
+    *
+    * The hardware typically calculates the scratch space pointer by taking
+    * the base address, and adding per-thread-scratch-space * thread ID.
+    * Extra padding can be necessary depending how the thread IDs are
+    * calculated for a particular shader stage.
+    */
+   if (devinfo->gen >= 9) {
+      devinfo->max_wm_threads = 64 /* threads-per-PSD */
+                              * devinfo->num_slices
+                              * 4; /* effective subslices per slice */
+   }
+
    return true;
 }