linux-kernel - [PATCH v2 08/11] drm/msm: adreno: request for maximum bus bandwidth usage

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Message-Id: <20241119-topic-sm8x50-gpu-bw-vote-v2-8-4deb87be2498@linaro.org>
Date: Tue, 19 Nov 2024 18:56:43 +0100
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Akhil P Oommen <quic_akhilpo@...cinc.com>, 
 Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>, 
 Stephen Boyd <sboyd@...nel.org>, "Rafael J. Wysocki" <rafael@...nel.org>, 
 Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>, 
 Konrad Dybcio <konradybcio@...nel.org>, 
 Abhinav Kumar <quic_abhinavk@...cinc.com>, 
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, 
 Marijn Suijten <marijn.suijten@...ainline.org>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Bjorn Andersson <andersson@...nel.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>
Cc: Connor Abbott <cwabbott0@...il.com>, linux-pm@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
 dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org, 
 devicetree@...r.kernel.org, Neil Armstrong <neil.armstrong@...aro.org>
Subject: [PATCH v2 08/11] drm/msm: adreno: request for maximum bus
 bandwidth usage

When requesting a DDR bandwidth level along a GPU frequency
level via the GMU, we can also specify the bus bandwidth usage in a 16bit
quantitized value.

For now simply request the maximum bus usage.

Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
---
 drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 11 +++++++++++
 drivers/gpu/drm/msm/adreno/a6xx_hfi.h |  5 +++++
 2 files changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
index dc2d0035544e7848e5c4ea27f1ea9a191f9c4991..36c0f67fd8e109aabf09a0804bacbed3593c39d7 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
@@ -134,6 +134,17 @@ void a6xx_gmu_set_freq(struct msm_gpu *gpu, struct dev_pm_opp *opp,
 			if (bw == gmu->gpu_bw_table[bw_index])
 				break;
 		}
+
+		if (bw_index) {
+			/*
+			 * Append AB vote to the maximum bus usage.
+			 * AB represents a quantitized 16bit value of the
+			 * max ddr bandwidth we could use, let's simply
+			 * request the maximum for now.
+			 */
+			bw_index |= AB_VOTE(MAX_AB_VOTE);
+			bw_index |= AB_VOTE_ENABLE;
+		}
 	}

 	gmu->current_perf_index = perf_index;
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_hfi.h b/drivers/gpu/drm/msm/adreno/a6xx_hfi.h
index 528110169398f69f16443a29a1594d19c36fb595..52ba4a07d7b9a709289acd244a751ace9bdaab5d 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_hfi.h
+++ b/drivers/gpu/drm/msm/adreno/a6xx_hfi.h
@@ -173,6 +173,11 @@ struct a6xx_hfi_gx_bw_perf_vote_cmd {
 	u32 bw;
 };

+#define AB_VOTE_MASK		GENMASK(31, 16)
+#define MAX_AB_VOTE		(FIELD_MAX(AB_VOTE_MASK) - 1)
+#define AB_VOTE(vote)		FIELD_PREP(AB_VOTE_MASK, (vote))
+#define AB_VOTE_ENABLE		BIT(8)
+
 #define HFI_H2F_MSG_PREPARE_SLUMBER 33

 struct a6xx_hfi_prep_slumber_cmd {

-- 
2.34.1