Re: [PATCH v1] drm/i915/dg2: enable G8 with a workaround

["Nilawar, Badal" <badal.nilawar@intel.com>]

On 07-10-2024 17:54, Raag Jadav wrote:
> Host BIOS doesn't enable G8 power mode due to an issue on DG2, so we
> enable it from kernel with Wa_14022698589. Currently it is enabled for
> all DG2 devices with the exception of a few, for which, it is enabled
> only when paired with whitelisted CPU models.
> 
> Signed-off-by: Raag Jadav <raag.jadav@intel.com>
> ---
>   drivers/gpu/drm/i915/gt/intel_workarounds.c | 43 +++++++++++++++++++++
>   drivers/gpu/drm/i915/i915_reg.h             |  1 +
>   2 files changed, 44 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> index e539a656cfc3..b2db51377488 100644
> --- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
> +++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> @@ -14,11 +14,30 @@
>   #include "intel_gt_mcr.h"
>   #include "intel_gt_print.h"
>   #include "intel_gt_regs.h"
> +#include "intel_pcode.h"
>   #include "intel_ring.h"
>   #include "intel_workarounds.h"
>   
>   #include "display/intel_fbc_regs.h"
>   
> +#ifdef CONFIG_X86
> +#include <asm/cpu_device_id.h>
> +#include <asm/intel-family.h>
> +
> +static const struct x86_cpu_id g8_cpu_ids[] = {
> +	X86_MATCH_VFM(INTEL_ALDERLAKE,		NULL),
> +	X86_MATCH_VFM(INTEL_ALDERLAKE_L,	NULL),
> +	X86_MATCH_VFM(INTEL_COMETLAKE,		NULL),
> +	X86_MATCH_VFM(INTEL_KABYLAKE,		NULL),
> +	X86_MATCH_VFM(INTEL_KABYLAKE_L,		NULL),
> +	X86_MATCH_VFM(INTEL_RAPTORLAKE,		NULL),
> +	X86_MATCH_VFM(INTEL_RAPTORLAKE_P,	NULL),
> +	X86_MATCH_VFM(INTEL_RAPTORLAKE_S,	NULL),
> +	X86_MATCH_VFM(INTEL_ROCKETLAKE,		NULL),
> +	{}
> +};
> +#endif
> +
>   /**
>    * DOC: Hardware workarounds
>    *
> @@ -1770,9 +1789,33 @@ static void wa_list_apply(const struct i915_wa_list *wal)
>   	intel_gt_mcr_unlock(gt, flags);
>   }
>   
> +#define DG2_G8_WA_RANGE_1		0x56A0 ... 0x56AF
> +#define DG2_G8_WA_RANGE_2		0x56B0 ... 0x56B9
> +
> +/* Wa_14022698589:dg2 */

As per bspecs correct Wa id for this Wa is 14022698537.

Regards,
Badal

> +static void intel_enable_g8(struct intel_uncore *uncore)
> +{
> +	if (IS_DG2(uncore->i915)) {
> +		switch (INTEL_DEVID(uncore->i915)) {
> +		case DG2_G8_WA_RANGE_1:
> +		case DG2_G8_WA_RANGE_2:
> +#ifdef CONFIG_X86
> +			if (!x86_match_cpu(g8_cpu_ids))
> +#endif
> +				return;
> +		}
> +
> +		snb_pcode_write_p(uncore, PCODE_POWER_SETUP,
> +				  POWER_SETUP_SUBCOMMAND_G8_ENABLE, 0, 0);
> +	}
> +}
> +
>   void intel_gt_apply_workarounds(struct intel_gt *gt)
>   {
>   	wa_list_apply(&gt->wa_list);
> +
> +	/* Special case for pcode mailbox which can't be on wa_list */
> +	intel_enable_g8(gt->uncore);
>   }
>   
>   static bool wa_list_verify(struct intel_gt *gt,
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 41f4350a7c6c..e948b194550c 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -3568,6 +3568,7 @@
>   #define   PCODE_POWER_SETUP			0x7C
>   #define     POWER_SETUP_SUBCOMMAND_READ_I1	0x4
>   #define     POWER_SETUP_SUBCOMMAND_WRITE_I1	0x5
> +#define     POWER_SETUP_SUBCOMMAND_G8_ENABLE	0x6
>   #define	    POWER_SETUP_I1_WATTS		REG_BIT(31)
>   #define	    POWER_SETUP_I1_SHIFT		6	/* 10.6 fixed point format */
>   #define	    POWER_SETUP_I1_DATA_MASK		REG_GENMASK(15, 0)