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

[Ghimiray, Himal Prasad]

On 23-11-2023 22:31, Matthew Auld wrote:
> On Thu, 23 Nov 2023 at 16:37, Matthew Auld
> <matthew.william.auld at gmail.com> wrote:
>> On Tue, 21 Nov 2023 at 10:01, Himal Prasad Ghimiray
>> <himal.prasad.ghimiray at intel.com> wrote:
>>> If bios disables flat ccs on igfx  make has_flat_ccs as 0 and notify
>>> via drm_info.
>>>
>>> Bspec:59255
>>>
>>> Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
>>> Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray at intel.com>
>> Huh, I wonder if that explains why on some particular LNL DUTs
>> compression just didn't seem to "work" for me.
>>
>> So should this information be passed along to userspace via some query
>> uAPI? Maybe there is some tradeoff between enabling compression and
>> other features (like coherency), and so knowing this might be useful?
> Another idea might be to reject any compressed pat_index, if the
> platform doesn't support flat_ccs?

Thanks for the review.  I will start the discussion regarding exposing 
this information via some uapi or

rejecting the compressed pat_index. Will come back with further info on 
this.

>
>>> ---
>>>   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;
>>> +
>>> +       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;
>>> +
>>>          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;
>>> --
>>> 2.25.1
>>>