[Intel-gfx] [PATCH 1/2] drm/i915/dg1: Compute MEM Bandwidth using MCHBAR

[Matthew Auld]

On Fri, 18 Jun 2021 at 17:14, Matthew Auld <matthew.auld at intel.com> wrote:
>
> From: Clint Taylor <clinton.a.taylor at intel.com>
>
> 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.

Any takers for these two patches? They are confirmed to light up the
display for DG1 and get us an accelerated desktop on drm-tip.

>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Matt Roper <matthew.d.roper at intel.com>
> Cc: Jani Saarinen <jani.saarinen at intel.com>
> Signed-off-by: Clint Taylor <clinton.a.taylor at intel.com>
> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
> ---
>  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;
>
>                 drm_dbg_kms(&dev_priv->drm,
> --
> 2.26.3
>
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