Historically we've selected and programmed a single MCR group/instance
ID at driver startup that will steer register accesses for GSLICE/DSS
ranges to a non-terminated instance. Any reads of these register ranges
that don't need a specific unicast access won't bother explicitly
resteering because the control register should already be set to a
suitable value to receive a non-terminated response. Any accesses to
other types of MCR ranges (MSLICE, LNCF, etc.) that are also satisfied
by the default steering target will also skip explicit re-steering at
runtime.
This approach has worked well for many years and many platforms, but our
hardware teams have recently advised us that they're not 100%
comfortable with our strategy going forward. They now suggest
explicitly steering reads of any multicast register at the time the
register access happens rather than relying on previously-programmed
steering values. In debug settings there could be external agents that
have adjusted the default steering without the driver's knowledge (e.g.,
we could do this manually with IGT's intel_reg today, although the
hardware teams also have other tools they use for debug and analysis).
In theory it would also be possible for bad firmware and/or incorrect
handling of power management events to clobber/wipe the steering
value we had previously initialized because they assume we'll be
re-programming it anyway.
Signed-off-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_gt_mcr.c | 40 +++++++++
drivers/gpu/drm/i915/gt/intel_gt_types.h | 1 +
drivers/gpu/drm/i915/gt/intel_workarounds.c | 98 ++++-----------------
3 files changed, 56 insertions(+), 83 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_mcr.c b/drivers/gpu/drm/i915/gt/intel_gt_mcr.c
index a9a9fa6881f2..787752367337 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_mcr.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_mcr.c
@@ -35,6 +35,7 @@
*/
static const char * const intel_steering_types[] = {
+ "GSLICE/DSS",
"L3BANK",
"MSLICE",
"LNCF",
@@ -45,6 +46,35 @@ static const struct intel_mmio_range icl_l3bank_steering_table[] = {
{},
};
+static const struct intel_mmio_range xehpsdv_dss_steering_table[] = {
+ { 0x005200, 0x0052FF },
+ { 0x005400, 0x007FFF },
+ { 0x008140, 0x00815F },
+ { 0x008D00, 0x008DFF },
+ { 0x0094D0, 0x00955F },
+ { 0x009680, 0x0096FF },
+ { 0x00DC00, 0x00DCFF },
+ { 0x00DE80, 0x00E8FF },
+ { 0x017000, 0x017FFF },
+ { 0x024A00, 0x024A7F },
+ {},
+};
+
+static const struct intel_mmio_range dg2_dss_steering_table[] = {
+ { 0x005200, 0x0052FF },
+ { 0x005400, 0x007FFF },
+ { 0x008140, 0x00815F },
+ { 0x008D00, 0x008DFF },
+ { 0x0094D0, 0x00955F },
+ { 0x009680, 0x0096FF },
+ { 0x00D800, 0x00D87F },
+ { 0x00DC00, 0x00DCFF },
+ { 0x00DE80, 0x00E8FF },
+ { 0x017000, 0x017FFF },
+ { 0x024A00, 0x024A7F },
+ {},
+};
+
static const struct intel_mmio_range xehpsdv_mslice_steering_table[] = {
{ 0x004000, 0x004AFF },
{ 0x00C800, 0x00CFFF },
@@ -87,9 +117,11 @@ void intel_gt_mcr_init(struct intel_gt *gt)
GEN12_MEML3_EN_MASK);
if (IS_DG2(i915)) {
+ gt->steering_table[DSS] = dg2_dss_steering_table;
gt->steering_table[MSLICE] = xehpsdv_mslice_steering_table;
gt->steering_table[LNCF] = dg2_lncf_steering_table;
} else if (IS_XEHPSDV(i915)) {
+ gt->steering_table[DSS] = xehpsdv_dss_steering_table;
gt->steering_table[MSLICE] = xehpsdv_mslice_steering_table;
gt->steering_table[LNCF] = xehpsdv_lncf_steering_table;
} else if (GRAPHICS_VER(i915) >= 11 &&
@@ -317,7 +349,15 @@ static void get_valid_steering(struct intel_gt *gt,
enum intel_steering_type type,
u8 *group, u8 *instance)
{
+ u32 dssmask = intel_sseu_get_subslices(>->info.sseu, 0);
+
switch (type) {
+ case DSS:
+ drm_WARN_ON(>->i915->drm, dssmask == 0);
+
+ *group = __ffs(dssmask) / GEN_DSS_PER_GSLICE;
+ *instance = __ffs(dssmask) % GEN_DSS_PER_GSLICE;
+ break;
case L3BANK:
GEM_DEBUG_WARN_ON(!gt->info.l3bank_mask); /* should be impossible! */
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_types.h b/drivers/gpu/drm/i915/gt/intel_gt_types.h
index 937b2e1a305e..b77bbaac7622 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_gt_types.h
@@ -54,6 +54,7 @@ struct intel_mmio_range {
* are listed here.
*/
enum intel_steering_type {
+ DSS,
L3BANK,
MSLICE,
LNCF,
diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
index 818ba71f4909..2486c6aa9d9d 100644
--- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
+++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
@@ -1160,87 +1160,6 @@ icl_wa_init_mcr(struct intel_gt *gt, struct i915_wa_list *wal)
__add_mcr_wa(gt, wal, slice, subslice);
}
-static void
-xehp_init_mcr(struct intel_gt *gt, struct i915_wa_list *wal)
-{
- const struct sseu_dev_info *sseu = >->info.sseu;
- unsigned long slice, subslice = 0, slice_mask = 0;
- u64 dss_mask = 0;
- u32 lncf_mask = 0;
- int i;
-
- /*
- * On Xe_HP the steering increases in complexity. There are now several
- * more units that require steering and we're not guaranteed to be able
- * to find a common setting for all of them. These are:
- * - GSLICE (fusable)
- * - DSS (sub-unit within gslice; fusable)
- * - L3 Bank (fusable)
- * - MSLICE (fusable)
- * - LNCF (sub-unit within mslice; always present if mslice is present)
- *
- * We'll do our default/implicit steering based on GSLICE (in the
- * sliceid field) and DSS (in the subsliceid field). If we can
- * find overlap between the valid MSLICE and/or LNCF values with
- * a suitable GSLICE, then we can just re-use the default value and
- * skip and explicit steering at runtime.
- *
- * We only need to look for overlap between GSLICE/MSLICE/LNCF to find
- * a valid sliceid value. DSS steering is the only type of steering
- * that utilizes the 'subsliceid' bits.
- *
- * Also note that, even though the steering domain is called "GSlice"
- * and it is encoded in the register using the gslice format, the spec
- * says that the combined (geometry | compute) fuse should be used to
- * select the steering.
- */
-
- /* Find the potential gslice candidates */
- dss_mask = intel_sseu_get_subslices(sseu, 0);
- slice_mask = intel_slicemask_from_dssmask(dss_mask, GEN_DSS_PER_GSLICE);
-
- /*
- * Find the potential LNCF candidates. Either LNCF within a valid
- * mslice is fine.
- */
- for_each_set_bit(i, >->info.mslice_mask, GEN12_MAX_MSLICES)
- lncf_mask |= (0x3 << (i * 2));
-
- /*
- * Are there any sliceid values that work for both GSLICE and LNCF
- * steering?
- */
- if (slice_mask & lncf_mask) {
- slice_mask &= lncf_mask;
- gt->steering_table[LNCF] = NULL;
- }
-
- /* How about sliceid values that also work for MSLICE steering? */
- if (slice_mask & gt->info.mslice_mask) {
- slice_mask &= gt->info.mslice_mask;
- gt->steering_table[MSLICE] = NULL;
- }
-
- slice = __ffs(slice_mask);
- subslice = __ffs(dss_mask >> (slice * GEN_DSS_PER_GSLICE));
- WARN_ON(subslice > GEN_DSS_PER_GSLICE);
- WARN_ON(dss_mask >> (slice * GEN_DSS_PER_GSLICE) == 0);
-
- __add_mcr_wa(gt, wal, slice, subslice);
-
- /*
- * SQIDI ranges are special because they use different steering
- * registers than everything else we work with. On XeHP SDV and
- * DG2-G10, any value in the steering registers will work fine since
- * all instances are present, but DG2-G11 only has SQIDI instances at
- * ID's 2 and 3, so we need to steer to one of those. For simplicity
- * we'll just steer to a hardcoded "2" since that value will work
- * everywhere.
- */
- __set_mcr_steering(wal, MCFG_MCR_SELECTOR, 0, 2);
- __set_mcr_steering(wal, SF_MCR_SELECTOR, 0, 2);
-}
-
static void
icl_gt_workarounds_init(struct intel_gt *gt, struct i915_wa_list *wal)
{
@@ -1388,8 +1307,9 @@ static void
xehpsdv_gt_workarounds_init(struct intel_gt *gt, struct i915_wa_list *wal)
{
struct drm_i915_private *i915 = gt->i915;
+ struct drm_printer p = drm_debug_printer("MCR Steering:");
- xehp_init_mcr(gt, wal);
+ intel_gt_mcr_report_steering(&p, gt, false);
/* Wa_1409757795:xehpsdv */
wa_mcr_write_or(wal, SCCGCTL94DC, CG3DDISURB);
@@ -1441,10 +1361,22 @@ xehpsdv_gt_workarounds_init(struct intel_gt *gt, struct i915_wa_list *wal)
static void
dg2_gt_workarounds_init(struct intel_gt *gt, struct i915_wa_list *wal)
{
+ struct drm_printer p = drm_debug_printer("MCR Steering:");
struct intel_engine_cs *engine;
int id;
- xehp_init_mcr(gt, wal);
+ intel_gt_mcr_report_steering(&p, gt, false);
