Re: [Intel-xe] [RFC v2 2/6] drm/xe/xe2: Determine bios enablement for flat ccs on igfx.

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

On Tue, 2023-11-21 at 15:39 +0530, Himal Prasad Ghimiray wrote:
> If bios disables flat ccs on igfx  make has_flat_ccs as 0 and notify
double space above                 ^^
> 
> via drm_info.
> 
> Bspec:59255
> 
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Signed-off-by: Himal Prasad Ghimiray
> <himal.prasad.ghimiray@intel.com>
> ---
>  drivers/gpu/drm/xe/regs/xe_gt_regs.h |  3 +++
>  drivers/gpu/drm/xe/xe_device.c       | 30
> ++++++++++++++++++++++++++++
>  2 files changed, 33 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/regs/xe_gt_regs.h
> b/drivers/gpu/drm/xe/regs/xe_gt_regs.h
> index cc27fe8fc363..b642301947f5 100644
> --- a/drivers/gpu/drm/xe/regs/xe_gt_regs.h
> +++ b/drivers/gpu/drm/xe/regs/xe_gt_regs.h
> @@ -142,6 +142,9 @@
>  #define XEHP_SLICE_COMMON_ECO_CHICKEN1         XE_REG_MCR(0x731c,
> XE_REG_OPTION_MASKED)
>  #define   MSC_MSAA_REODER_BUF_BYPASS_DISABLE   REG_BIT(14)
>  
> +#define XE2_FLAT_CCS_BASE_RANGE_LOWER          XE_REG_MCR(0x8800)
> +#define   XE2_FLAT_CCS_ENABLE                  REG_BIT(0)
> +
>  #define VF_PREEMPTION                          XE_REG(0x83a4,
> XE_REG_OPTION_MASKED)
>  #define   PREEMPTION_VERTEX_COUNT              REG_GENMASK(15, 0)
>  
> diff --git a/drivers/gpu/drm/xe/xe_device.c
> b/drivers/gpu/drm/xe/xe_device.c
> index 8be765adf702..07a3e4cf48d1 100644
> --- a/drivers/gpu/drm/xe/xe_device.c
> +++ b/drivers/gpu/drm/xe/xe_device.c
> @@ -16,6 +16,7 @@
>  #include <drm/xe_drm.h>
>  
>  #include "regs/xe_regs.h"
> +#include "regs/xe_gt_regs.h"
>  #include "xe_bo.h"
>  #include "xe_debugfs.h"
>  #include "xe_display.h"
> @@ -25,6 +26,7 @@
>  #include "xe_exec_queue.h"
>  #include "xe_exec.h"
>  #include "xe_gt.h"
> +#include "xe_gt_mcr.h"
>  #include "xe_irq.h"
>  #include "xe_mmio.h"
>  #include "xe_module.h"
> @@ -342,6 +344,29 @@ static void xe_device_sanitize(struct drm_device
> *drm, void *arg)
>                 xe_gt_sanitize(gt);
>  }
>  
> +static int xe_device_set_has_flat_ccs(struct  xe_device *xe)
> +{
> +       u32 reg;
> +       int err;
> +
> +       if (IS_DGFX(xe) || GRAPHICS_VER(xe) < 20 || !xe-
> >info.has_flat_ccs)
> +               return 0;

Depending on the outcome of the iommu discussion we might need to check
for iommu present here as well?

> +
> +       struct xe_gt *gt = xe_root_mmio_gt(xe);
> +
> +       err = xe_force_wake_get(gt_to_fw(gt), XE_FW_GT);
> +       if (err)
> +               return err;
> +
> +       reg = xe_gt_mcr_unicast_read_any(gt,
> XE2_FLAT_CCS_BASE_RANGE_LOWER);
> +       xe->info.has_flat_ccs = (reg & XE2_FLAT_CCS_ENABLE);
> +
> +       if (!xe->info.has_flat_ccs)
> +               drm_info(&xe->drm,
> +                        "Flat CCS has been disabled in bios, May
> lead to performance impact");
> +       return 0;
> +}
> +
>  int xe_device_probe(struct xe_device *xe)
>  {
>         struct xe_tile *tile;
> @@ -352,6 +377,7 @@ int xe_device_probe(struct xe_device *xe)
>         xe_pat_init_early(xe);
>  
>         xe->info.mem_region_mask = 1;
> +

Unrelated change.

>         err = xe_display_init_nommio(xe);
>         if (err)
>                 return err;
> @@ -390,6 +416,10 @@ int xe_device_probe(struct xe_device *xe)
>                         goto err_irq_shutdown;
>         }
>  
> +       err = xe_device_set_has_flat_ccs(xe);
> +       if (err)
> +               return err;
> +
>         err = xe_mmio_probe_vram(xe);
>         if (err)
>                 goto err_irq_shutdown;