Re: [PATCH 1/2] drm/i915/dg1: Compute MEM Bandwidth using MCHBAR

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On Mon, Jun 21, 2021 at 09:44:35AM +0100, Matthew Auld wrote:
On 21/06/2021 06:46, Lucas De Marchi wrote:
On Fri, Jun 18, 2021 at 9:14 AM Matthew Auld <matthew.auld@xxxxxxxxx> wrote:

From: Clint Taylor <clinton.a.taylor@xxxxxxxxx>

The PUNIT FW is currently returning 0 for all memory bandwidth
parameters. Read the values directly from MCHBAR offsets 0x5918 and
0x4000(4). This is a temporary WA until the PUNIT FW returns valid
values.

This is supposed to be fixed for quite some time and this WA shouldn't
be needed. Is this really happening?

Yes, from the sample of machines I have tried recently they all seem to need it. Same for Thomas, who also confirmed that these two patches are needed. In dmesg I get:

[drm:icl_get_bw_info.isra.0 [i915]] Failed to get memory subsystem information via pcode. IFWI needs update. Trying with MCHBAR

My point was:  is this something reproducible on machines outside Intel?
Machines from CI or internal should follow the recommendation from the
message above: "IFWI needs update".

Internal CI looks to be the same from a quick look.

:(



Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Cc: Matt Roper <matthew.d.roper@xxxxxxxxx>
Cc: Jani Saarinen <jani.saarinen@xxxxxxxxx>
Signed-off-by: Clint Taylor <clinton.a.taylor@xxxxxxxxx>
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>

humn... no s-o-b from you?

Will add.


Lucas De Marchi

---
 drivers/gpu/drm/i915/display/intel_bw.c | 54 ++++++++++++++++++++++++-
 1 file changed, 53 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_bw.c b/drivers/gpu/drm/i915/display/intel_bw.c
index bfb398f0432e..f3d8ff4ee0db 100644
--- a/drivers/gpu/drm/i915/display/intel_bw.c
+++ b/drivers/gpu/drm/i915/display/intel_bw.c
@@ -23,6 +23,53 @@ struct intel_qgv_info {
        u8 t_bl;
 };

+#define SA_PERF_STATUS_0_0_0_MCHBAR_PC _MMIO(MCHBAR_MIRROR_BASE_SNB + 0x5918)
+#define  DG1_QCLK_RATIO_MASK (0xFF << 2)
+#define  DG1_QCLK_RATIO_SHIFT 2
+#define  DG1_QCLK_REFERENCE (1 << 10)
+
+#define MCHBAR_CH0_CR_TC_PRE_0_0_0_MCHBAR _MMIO(MCHBAR_MIRROR_BASE_SNB + 0x4000)
+#define MCHBAR_CH0_CR_TC_PRE_0_0_0_MCHBAR_HIGH _MMIO(MCHBAR_MIRROR_BASE_SNB + 0x4004)
+#define MCHBAR_CH1_CR_TC_PRE_0_0_0_MCHBAR _MMIO(MCHBAR_MIRROR_BASE_SNB + 0x4400)
+#define MCHBAR_CH1_CR_TC_PRE_0_0_0_MCHBAR_HIGH _MMIO(MCHBAR_MIRROR_BASE_SNB + 0x4404)
+#define  DG1_DRAM_T_RCD_MASK (0x7F << 9)
+#define  DG1_DRAM_T_RCD_SHIFT 9
+#define  DG1_DRAM_T_RDPRE_MASK (0x3F << 11)
+#define  DG1_DRAM_T_RDPRE_SHIFT 11
+#define  DG1_DRAM_T_RAS_MASK (0xFF << 1)
+#define  DG1_DRAM_T_RAS_SHIFT 1
+#define  DG1_DRAM_T_RP_MASK (0x7F << 0)
+#define  DG1_DRAM_T_RP_SHIFT 0
+
+static int dg1_mchbar_read_qgv_point_info(struct drm_i915_private *dev_priv,
+                                         struct intel_qgv_point *sp,
+                                         int point)
+{
+       u32 val = 0;
+       u32 dclk_ratio = 0, dclk_reference = 0;
+
+       val = intel_uncore_read(&dev_priv->uncore, SA_PERF_STATUS_0_0_0_MCHBAR_PC);
+       dclk_ratio = (val & DG1_QCLK_RATIO_MASK) >> DG1_QCLK_RATIO_SHIFT;
+       if (val & DG1_QCLK_REFERENCE)
+               dclk_reference = 6; /* 6 * 16.666 MHz = 100 MHz */
+       else
+               dclk_reference = 8; /* 8 * 16.666 MHz = 133 MHz */
+       sp->dclk = dclk_ratio * dclk_reference;
+       if (sp->dclk == 0)
+               return -EINVAL;
+
+       val = intel_uncore_read(&dev_priv->uncore, MCHBAR_CH0_CR_TC_PRE_0_0_0_MCHBAR);
+       sp->t_rp = (val & DG1_DRAM_T_RP_MASK) >> DG1_DRAM_T_RP_SHIFT;
+       sp->t_rdpre = (val & DG1_DRAM_T_RDPRE_MASK) >> DG1_DRAM_T_RDPRE_SHIFT;
+
+       val = intel_uncore_read(&dev_priv->uncore, MCHBAR_CH0_CR_TC_PRE_0_0_0_MCHBAR_HIGH);
+       sp->t_rcd = (val & DG1_DRAM_T_RCD_MASK) >> DG1_DRAM_T_RCD_SHIFT;
+       sp->t_ras = (val & DG1_DRAM_T_RAS_MASK) >> DG1_DRAM_T_RAS_SHIFT;
+
+       sp->t_rc = sp->t_rp + sp->t_ras;
+       return 0;
+}
+
 static int icl_pcode_read_qgv_point_info(struct drm_i915_private *dev_priv,
                                         struct intel_qgv_point *sp,
                                         int point)
@@ -100,7 +147,12 @@ static int icl_get_qgv_points(struct drm_i915_private *dev_priv,
                struct intel_qgv_point *sp = &qi->points[i];

                ret = icl_pcode_read_qgv_point_info(dev_priv, sp, i);
-               if (ret)
+               if (IS_DG1(dev_priv) && (ret || sp->dclk == 0)) {
+                       drm_dbg_kms(&dev_priv->drm, "Failed to get memory subsystem information via pcode. IFWI needs update. Trying with MCHBAR\n");
+                       ret = dg1_mchbar_read_qgv_point_info(dev_priv, sp, i);
+                       if (ret)
+                               return ret;
+               } else if (ret)
                        return ret;

IMO this looks a little bit nicer to read:

	ret = icl_pcode_read_qgv_point_info(dev_priv, sp, i);
	if (IS_DG1(dev_priv) && (ret || sp->dclk == 0)) {
		drm_dbg_kms(&dev_priv->drm, "Failed to get memory subsystem information via pcode. IFWI needs update. Trying with MCHBAR\n");
		ret = dg1_mchbar_read_qgv_point_info(dev_priv, sp, i);
	}

	if (ret)
		return ret;


Lucas De Marchi
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