[Intel-gfx] [PATCH v5 02/12] drm/i915/mtl: Synchronize i915/BIOS on C6 enabling

[Umesh Nerlige Ramappa]

On Wed, Mar 15, 2023 at 05:09:22PM -0700, Umesh Nerlige Ramappa wrote:
>From: Vinay Belgaumkar <vinay.belgaumkar at intel.com>
>
>If BIOS enables/disables C6, i915 should do the same. Also, retain
>this value across driver reloads. This is needed only for MTL as
>of now due to an existing bug in OA which needs C6 disabled for
>it to function. BIOS behavior is also different across platforms
>in terms of how C6 is enabled.
>
>Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar at intel.com>
>---
> drivers/gpu/drm/i915/gt/intel_rc6.c       | 28 +++++++++++++++++++++++
> drivers/gpu/drm/i915/gt/intel_rc6.h       |  2 ++
> drivers/gpu/drm/i915/gt/intel_rc6_types.h |  2 ++
> 3 files changed, 32 insertions(+)
>
>diff --git a/drivers/gpu/drm/i915/gt/intel_rc6.c b/drivers/gpu/drm/i915/gt/intel_rc6.c
>index 5c91622dfca4..f760586f9f46 100644
>--- a/drivers/gpu/drm/i915/gt/intel_rc6.c
>+++ b/drivers/gpu/drm/i915/gt/intel_rc6.c
>@@ -420,6 +420,21 @@ static void vlv_rc6_enable(struct intel_rc6 *rc6)
> 	    GEN7_RC_CTL_TO_MODE | VLV_RC_CTL_CTX_RST_PARALLEL;
> }
>
>+bool intel_check_bios_c6_setup(struct intel_rc6 *rc6)
>+{
>+	if (!rc6->bios_state_captured) {
>+		struct intel_uncore *uncore = rc6_to_uncore(rc6);
>+		intel_wakeref_t wakeref;
>+
>+		with_intel_runtime_pm(uncore->rpm, wakeref)
>+			rc6->bios_rc_state = intel_uncore_read(uncore, GEN6_RC_STATE);
>+
>+		rc6->bios_state_captured = true;
>+	}
>+
>+	return rc6->bios_rc_state & RC_SW_TARGET_STATE_MASK;
>+}
>+
> static bool bxt_check_bios_rc6_setup(struct intel_rc6 *rc6)
> {
> 	struct intel_uncore *uncore = rc6_to_uncore(rc6);
>@@ -486,6 +501,7 @@ static bool bxt_check_bios_rc6_setup(struct intel_rc6 *rc6)
> static bool rc6_supported(struct intel_rc6 *rc6)
> {
> 	struct drm_i915_private *i915 = rc6_to_i915(rc6);
>+	struct intel_gt *gt = rc6_to_gt(rc6);
>
> 	if (!HAS_RC6(i915))
> 		return false;
>@@ -502,6 +518,13 @@ static bool rc6_supported(struct intel_rc6 *rc6)
> 		return false;
> 	}
>
>+	if (IS_METEORLAKE(gt->i915) &&
>+	    !intel_check_bios_c6_setup(rc6)) {
>+		drm_notice(&i915->drm,
>+			   "C6 disabled by BIOS\n");
>+		return false;
>+	}
>+
> 	return true;
> }
>
>@@ -699,9 +722,14 @@ void intel_rc6_disable(struct intel_rc6 *rc6)
> void intel_rc6_fini(struct intel_rc6 *rc6)
> {
> 	struct drm_i915_gem_object *pctx;
>+	struct intel_uncore *uncore = rc6_to_uncore(rc6);
>
> 	intel_rc6_disable(rc6);
>
>+	/* We want the BIOS C6 state preserved across loads for MTL */
>+	if (IS_METEORLAKE(rc6_to_i915(rc6)) && rc6->bios_state_captured)
>+		set(uncore, GEN6_RC_STATE, rc6->bios_rc_state);
>+

Assuming bios_state_captured will be false on driver load because gt is 
zalloc-ed. With that, this lgtm

Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa at intel.com>

Regards,
Umesh
> 	pctx = fetch_and_zero(&rc6->pctx);
> 	if (pctx)
> 		i915_gem_object_put(pctx);
>diff --git a/drivers/gpu/drm/i915/gt/intel_rc6.h b/drivers/gpu/drm/i915/gt/intel_rc6.h
>index 456fa668a276..e137c2c397c2 100644
>--- a/drivers/gpu/drm/i915/gt/intel_rc6.h
>+++ b/drivers/gpu/drm/i915/gt/intel_rc6.h
>@@ -27,4 +27,6 @@ u64 intel_rc6_residency_us(struct intel_rc6 *rc6, enum intel_rc6_res_type id);
> void intel_rc6_print_residency(struct seq_file *m, const char *title,
> 			       enum intel_rc6_res_type id);
>
>+bool intel_check_bios_c6_setup(struct intel_rc6 *rc6);
>+
> #endif /* INTEL_RC6_H */
>diff --git a/drivers/gpu/drm/i915/gt/intel_rc6_types.h b/drivers/gpu/drm/i915/gt/intel_rc6_types.h
>index fa23c4dce00b..cd4587098162 100644
>--- a/drivers/gpu/drm/i915/gt/intel_rc6_types.h
>+++ b/drivers/gpu/drm/i915/gt/intel_rc6_types.h
>@@ -29,6 +29,7 @@ struct intel_rc6 {
> 	u64 cur_residency[INTEL_RC6_RES_MAX];
>
> 	u32 ctl_enable;
>+	u32 bios_rc_state;
>
> 	struct drm_i915_gem_object *pctx;
>
>@@ -36,6 +37,7 @@ struct intel_rc6 {
> 	bool enabled : 1;
> 	bool manual : 1;
> 	bool wakeref : 1;
>+	bool bios_state_captured : 1;
> };
>
> #endif /* INTEL_RC6_TYPES_H */
>-- 
>2.36.1
>