Re: [Intel-gfx] [PATCH v7 2/2] drm/i915: Implement WaProgramMgsrForL3BankSpecificMmioReads

2018-04-16 Thread Oscar Mateo 



On 04/16/2018 02:24 PM, Yunwei Zhang wrote:

L3Bank could be fused off in hardware for debug purpose, and it
is possible that subslice is enabled while its corresponding L3Bank pairs
are disabled. In such case, if MCR packet control register(0xFDC) is
programed to point to a disabled bank pair, a MMIO read into L3Bank range
will return 0 instead of correct values.

However, this is not going to be the case in any production silicon.
Therefore, we only check at initialization and issue a warning should
this really happen.

References: HSDES#1405586840

v2:
  - use fls instead of find_last_bit (Chris)
  - use is_power_of_2() instead of counting bit set (Chris)
v3:
  - rebase on latest tip
v5:
  - Added references (Mika)
  - Move local variable into scope where they are used (Ursulin)
  - use a new local variable to reduce long line of code (Ursulin)
v6:
  - Some coding style and use more local variables for clearer
logic (Ursulin)
v7:
  - Rebased.

Cc: Oscar Mateo 
Cc: Michel Thierry 
Cc: Joonas Lahtinen 
Cc: Chris Wilson 
Cc: Mika Kuoppala 
Cc: Tvrtko Ursulin 
Signed-off-by: Yunwei Zhang 
---
  drivers/gpu/drm/i915/i915_reg.h  |  4 
  drivers/gpu/drm/i915/intel_workarounds.c | 25 +
  2 files changed, 29 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index fb10602..6c9c01b 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2709,6 +2709,10 @@ enum i915_power_well_id {
  #define   GEN10_F2_SS_DIS_SHIFT   18
  #define   GEN10_F2_SS_DIS_MASK(0xf << GEN10_F2_SS_DIS_SHIFT)
  
+#define	GEN10_MIRROR_FUSE3		_MMIO(0x9118)

+#define GEN10_L3BANK_PAIR_COUNT 4
+#define GEN10_L3BANK_MASK   0x0F
+
  #define GEN8_EU_DISABLE0  _MMIO(0x9134)
  #define   GEN8_EU_DIS0_S0_MASK0xff
  #define   GEN8_EU_DIS0_S1_SHIFT   24
diff --git a/drivers/gpu/drm/i915/intel_workarounds.c 
b/drivers/gpu/drm/i915/intel_workarounds.c
index 8a2354e..fe1c908 100644
--- a/drivers/gpu/drm/i915/intel_workarounds.c
+++ b/drivers/gpu/drm/i915/intel_workarounds.c
@@ -647,8 +647,33 @@ static void cfl_gt_workarounds_apply(struct 
drm_i915_private *dev_priv)
  
  static void wa_init_mcr(struct drm_i915_private *dev_priv)

  {
+   const struct sseu_dev_info *sseu = &(INTEL_INFO(dev_priv)->sseu);
u32 mcr;
  
+	/*

+* L3Banks could be fused off in single slice scenario, however, if
+* more than one slice is enabled, this should not happen.
+*/
+   if (is_power_of_2(sseu->slice_mask)) {
+   /*
+* WaProgramMgsrForL3BankSpecificMmioReads:
+* read FUSE3 for enabled L3 Bank IDs, if L3 Bank matches
+* enabled subslice, no need to redirect MCR packet
+*/
+   u32 slice = fls(sseu->slice_mask);
+   u32 fuse3 = I915_READ(GEN10_MIRROR_FUSE3);
+   u8 ss_mask = sseu->subslice_mask[slice];
+
+   u8 enabled_mask = (ss_mask | ss_mask >> 4) & 0xf;
+   u8 disabled_mask = fuse3 & 0xf;
+
+   /*
+* Production silicon should have matched L3Bank and
+* subslice enabled
+*/
+   WARN_ON((enabled_mask & disabled_mask) != enabled_mask);
+   }
+


Reviewed-by: Oscar Mateo 

And this warning is also required for Icelake.


mcr = I915_READ(GEN8_MCR_SELECTOR);
mcr = calculate_mcr(dev_priv, mcr);
I915_WRITE(GEN8_MCR_SELECTOR, mcr);


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[Intel-gfx] [PATCH v7 2/2] drm/i915: Implement WaProgramMgsrForL3BankSpecificMmioReads

2018-04-16 Thread Yunwei Zhang 
L3Bank could be fused off in hardware for debug purpose, and it
is possible that subslice is enabled while its corresponding L3Bank pairs
are disabled. In such case, if MCR packet control register(0xFDC) is
programed to point to a disabled bank pair, a MMIO read into L3Bank range
will return 0 instead of correct values.

However, this is not going to be the case in any production silicon.
Therefore, we only check at initialization and issue a warning should
this really happen.

References: HSDES#1405586840

v2:
 - use fls instead of find_last_bit (Chris)
 - use is_power_of_2() instead of counting bit set (Chris)
v3:
 - rebase on latest tip
v5:
 - Added references (Mika)
 - Move local variable into scope where they are used (Ursulin)
 - use a new local variable to reduce long line of code (Ursulin)
v6:
 - Some coding style and use more local variables for clearer
   logic (Ursulin)
v7:
 - Rebased.

Cc: Oscar Mateo 
Cc: Michel Thierry 
Cc: Joonas Lahtinen 
Cc: Chris Wilson 
Cc: Mika Kuoppala 
Cc: Tvrtko Ursulin 
Signed-off-by: Yunwei Zhang 
---
 drivers/gpu/drm/i915/i915_reg.h  |  4 
 drivers/gpu/drm/i915/intel_workarounds.c | 25 +
 2 files changed, 29 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index fb10602..6c9c01b 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2709,6 +2709,10 @@ enum i915_power_well_id {
 #define   GEN10_F2_SS_DIS_SHIFT18
 #define   GEN10_F2_SS_DIS_MASK (0xf << GEN10_F2_SS_DIS_SHIFT)
 
+#defineGEN10_MIRROR_FUSE3  _MMIO(0x9118)
+#define GEN10_L3BANK_PAIR_COUNT 4
+#define GEN10_L3BANK_MASK   0x0F
+
 #define GEN8_EU_DISABLE0   _MMIO(0x9134)
 #define   GEN8_EU_DIS0_S0_MASK 0xff
 #define   GEN8_EU_DIS0_S1_SHIFT24
diff --git a/drivers/gpu/drm/i915/intel_workarounds.c 
b/drivers/gpu/drm/i915/intel_workarounds.c
index 8a2354e..fe1c908 100644
--- a/drivers/gpu/drm/i915/intel_workarounds.c
+++ b/drivers/gpu/drm/i915/intel_workarounds.c
@@ -647,8 +647,33 @@ static void cfl_gt_workarounds_apply(struct 
drm_i915_private *dev_priv)
 
 static void wa_init_mcr(struct drm_i915_private *dev_priv)
 {
+   const struct sseu_dev_info *sseu = &(INTEL_INFO(dev_priv)->sseu);
u32 mcr;
 
+   /*
+* L3Banks could be fused off in single slice scenario, however, if
+* more than one slice is enabled, this should not happen.
+*/
+   if (is_power_of_2(sseu->slice_mask)) {
+   /*
+* WaProgramMgsrForL3BankSpecificMmioReads:
+* read FUSE3 for enabled L3 Bank IDs, if L3 Bank matches
+* enabled subslice, no need to redirect MCR packet
+*/
+   u32 slice = fls(sseu->slice_mask);
+   u32 fuse3 = I915_READ(GEN10_MIRROR_FUSE3);
+   u8 ss_mask = sseu->subslice_mask[slice];
+
+   u8 enabled_mask = (ss_mask | ss_mask >> 4) & 0xf;
+   u8 disabled_mask = fuse3 & 0xf;
+
+   /*
+* Production silicon should have matched L3Bank and
+* subslice enabled
+*/
+   WARN_ON((enabled_mask & disabled_mask) != enabled_mask);
+   }
+
mcr = I915_READ(GEN8_MCR_SELECTOR);
mcr = calculate_mcr(dev_priv, mcr);
I915_WRITE(GEN8_MCR_SELECTOR, mcr);
-- 
2.7.4

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