[PATCH v2 0/5] MDSS reg bus interconnect

[PATCH v2 0/5] MDSS reg bus interconnect

[Konrad Dybcio]

v1 -> v2:
- Fix "Mbps" -> "MBps" [5/5]
- Add an interconnects: entry in dt-bindings (and not only -names..) [1/5]

v1: https://lore.kernel.org/r/20230417-topic-dpu_regbus-v1-0-06fbdc1643c0@linaro.org

Apart from the already handled data bus (MAS_MDP_Pn<->DDR), there's
another path that needs to be handled to ensure MDSS functions properly,
namely the "reg bus", a.k.a the CPU-MDSS interconnect.

Gating that path may have a variety of effects.. from none to otherwise
inexplicable DSI timeouts..

This series tries to address the lack of that.

Example path:

interconnects = <&bimc MASTER_AMPSS_M0 0 &config_noc SLAVE_DISPLAY_CFG 0>;

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
---
Konrad Dybcio (5):
      dt-bindings: display/msm: Add reg bus interconnect
      drm/msm/dpu1: Rename path references to mdp_path
      drm/msm/mdss: Rename path references to mdp_path
      drm/msm/mdss: Handle the reg bus ICC path
      drm/msm/dpu1: Handle the reg bus ICC path

 .../bindings/display/msm/mdss-common.yaml          |  2 ++
 drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c      | 10 +++----
 drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c            | 34 ++++++++++++++++-----
 drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h            |  5 ++--
 drivers/gpu/drm/msm/msm_mdss.c                     | 35 ++++++++++++++--------
 5 files changed, 58 insertions(+), 28 deletions(-)
---
base-commit: 4aa1da8d99724f6c0b762b58a71cee7c5e2e109b
change-id: 20230417-topic-dpu_regbus-abc94a770952

Best regards,
-- 
Konrad Dybcio <konrad.dybcio@linaro.org>

[PATCH v2 1/5] dt-bindings: display/msm: Add reg bus interconnect

[Konrad Dybcio]

Apart from the already handled data bus (MAS_MDP_Pn<->DDR), there's
another path that needs to be handled to ensure MDSS functions properly,
namely the "reg bus", a.k.a the CPU-MDSS interconnect.

Gating that path may have a variety of effects.. from none to otherwise
inexplicable DSI timeouts..

Describe it in bindings to allow for use in device trees.

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
---
 Documentation/devicetree/bindings/display/msm/mdss-common.yaml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/msm/mdss-common.yaml b/Documentation/devicetree/bindings/display/msm/mdss-common.yaml
index ccd7d6417523..30a8aed4289a 100644
--- a/Documentation/devicetree/bindings/display/msm/mdss-common.yaml
+++ b/Documentation/devicetree/bindings/display/msm/mdss-common.yaml
@@ -66,12 +66,14 @@ properties:
     items:
       - description: Interconnect path from mdp0 (or a single mdp) port to the data bus
       - description: Interconnect path from mdp1 port to the data bus
+      - description: Interconnect path from CPU to the reg bus
 
   interconnect-names:
     minItems: 1
     items:
       - const: mdp0-mem
       - const: mdp1-mem
+      - const: cpu-cfg
 
   resets:
     items:

-- 
2.40.0

Re: [PATCH v2 1/5] dt-bindings: display/msm: Add reg bus interconnect

[Krzysztof Kozlowski]

On 18/04/2023 14:10, Konrad Dybcio wrote:
> Apart from the already handled data bus (MAS_MDP_Pn<->DDR), there's
> another path that needs to be handled to ensure MDSS functions properly,
> namely the "reg bus", a.k.a the CPU-MDSS interconnect.
> 
> Gating that path may have a variety of effects.. from none to otherwise
> inexplicable DSI timeouts..
> 
> Describe it in bindings to allow for use in device trees.
> 
> Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof

[PATCH v2 2/5] drm/msm/dpu1: Rename path references to mdp_path

[Konrad Dybcio]

The DPU1 driver needs to handle all MDPn<->DDR paths, as well as
CPU<->SLAVE_DISPLAY_CFG. The former ones share how their values are
calculated, but the latter one has static predefines spanning all SoCs.

In preparation for supporting the CPU<->SLAVE_DISPLAY_CFG path, rename
the path-related struct members to include "mdp_".

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c | 10 +++++-----
 drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c       | 12 ++++++------
 drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h       |  4 ++--
 3 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c
index 1d9d83d7b99e..349c6cb3301d 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c
@@ -230,18 +230,18 @@ static int _dpu_core_perf_crtc_update_bus(struct dpu_kms *kms,
 
 			DRM_DEBUG_ATOMIC("crtc=%d bw=%llu paths:%d\n",
 				  tmp_crtc->base.id,
-				  dpu_cstate->new_perf.bw_ctl, kms->num_paths);
+				  dpu_cstate->new_perf.bw_ctl, kms->num_mdp_paths);
 		}
 	}
 
-	if (!kms->num_paths)
+	if (!kms->num_mdp_paths)
 		return 0;
 
 	avg_bw = perf.bw_ctl;
-	do_div(avg_bw, (kms->num_paths * 1000)); /*Bps_to_icc*/
+	do_div(avg_bw, (kms->num_mdp_paths * 1000)); /*Bps_to_icc*/
 
-	for (i = 0; i < kms->num_paths; i++)
-		icc_set_bw(kms->path[i], avg_bw, perf.max_per_pipe_ib);
+	for (i = 0; i < kms->num_mdp_paths; i++)
+		icc_set_bw(kms->mdp_path[i], avg_bw, perf.max_per_pipe_ib);
 
 	return ret;
 }
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
index 0e7a68714e9e..dd6c1c40ab9e 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
@@ -397,12 +397,12 @@ static int dpu_kms_parse_data_bus_icc_path(struct dpu_kms *dpu_kms)
 	if (IS_ERR_OR_NULL(path0))
 		return PTR_ERR_OR_ZERO(path0);
 
-	dpu_kms->path[0] = path0;
-	dpu_kms->num_paths = 1;
+	dpu_kms->mdp_path[0] = path0;
+	dpu_kms->num_mdp_paths = 1;
 
 	if (!IS_ERR_OR_NULL(path1)) {
-		dpu_kms->path[1] = path1;
-		dpu_kms->num_paths++;
+		dpu_kms->mdp_path[1] = path1;
+		dpu_kms->num_mdp_paths++;
 	}
 	return 0;
 }
@@ -1238,8 +1238,8 @@ static int __maybe_unused dpu_runtime_suspend(struct device *dev)
 	dev_pm_opp_set_rate(dev, 0);
 	clk_bulk_disable_unprepare(dpu_kms->num_clocks, dpu_kms->clocks);
 
-	for (i = 0; i < dpu_kms->num_paths; i++)
-		icc_set_bw(dpu_kms->path[i], 0, 0);
+	for (i = 0; i < dpu_kms->num_mdp_paths; i++)
+		icc_set_bw(dpu_kms->mdp_path[i], 0, 0);
 
 	return 0;
 }
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
index aca39a4689f4..d5d9bec90705 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
@@ -109,8 +109,8 @@ struct dpu_kms {
 	 * when disabled.
 	 */
 	atomic_t bandwidth_ref;
-	struct icc_path *path[2];
-	u32 num_paths;
+	struct icc_path *mdp_path[2];
+	u32 num_mdp_paths;
 };
 
 struct vsync_info {

-- 
2.40.0

Re: [PATCH v2 2/5] drm/msm/dpu1: Rename path references to mdp_path

[Dmitry Baryshkov]

On 18/04/2023 15:10, Konrad Dybcio wrote:
> The DPU1 driver needs to handle all MDPn<->DDR paths, as well as
> CPU<->SLAVE_DISPLAY_CFG. The former ones share how their values are
> calculated, but the latter one has static predefines spanning all SoCs.
> 
> In preparation for supporting the CPU<->SLAVE_DISPLAY_CFG path, rename
> the path-related struct members to include "mdp_".
> 
> Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
> ---
>   drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c | 10 +++++-----
>   drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c       | 12 ++++++------
>   drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h       |  4 ++--
>   3 files changed, 13 insertions(+), 13 deletions(-)

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

-- 
With best wishes
Dmitry

[PATCH v2 3/5] drm/msm/mdss: Rename path references to mdp_path

[Konrad Dybcio]

The DPU1 driver needs to handle all MDPn<->DDR paths, as well as
CPU<->SLAVE_DISPLAY_CFG. The former ones share how their values are
calculated, but the latter one has static predefines spanning all SoCs.

In preparation for supporting the CPU<->SLAVE_DISPLAY_CFG path, rename
the path-related struct members to include "mdp_".

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
---
 drivers/gpu/drm/msm/msm_mdss.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_mdss.c b/drivers/gpu/drm/msm/msm_mdss.c
index e8c93731aaa1..9e2ce7f22677 100644
--- a/drivers/gpu/drm/msm/msm_mdss.c
+++ b/drivers/gpu/drm/msm/msm_mdss.c
@@ -48,8 +48,8 @@ struct msm_mdss {
 		struct irq_domain *domain;
 	} irq_controller;
 	const struct msm_mdss_data *mdss_data;
-	struct icc_path *path[2];
-	u32 num_paths;
+	struct icc_path *mdp_path[2];
+	u32 num_mdp_paths;
 };
 
 static int msm_mdss_parse_data_bus_icc_path(struct device *dev,
@@ -62,13 +62,13 @@ static int msm_mdss_parse_data_bus_icc_path(struct device *dev,
 	if (IS_ERR_OR_NULL(path0))
 		return PTR_ERR_OR_ZERO(path0);
 
-	msm_mdss->path[0] = path0;
-	msm_mdss->num_paths = 1;
+	msm_mdss->mdp_path[0] = path0;
+	msm_mdss->num_mdp_paths = 1;
 
 	path1 = of_icc_get(dev, "mdp1-mem");
 	if (!IS_ERR_OR_NULL(path1)) {
-		msm_mdss->path[1] = path1;
-		msm_mdss->num_paths++;
+		msm_mdss->mdp_path[1] = path1;
+		msm_mdss->num_mdp_paths++;
 	}
 
 	return 0;
@@ -79,16 +79,16 @@ static void msm_mdss_put_icc_path(void *data)
 	struct msm_mdss *msm_mdss = data;
 	int i;
 
-	for (i = 0; i < msm_mdss->num_paths; i++)
-		icc_put(msm_mdss->path[i]);
+	for (i = 0; i < msm_mdss->num_mdp_paths; i++)
+		icc_put(msm_mdss->mdp_path[i]);
 }
 
 static void msm_mdss_icc_request_bw(struct msm_mdss *msm_mdss, unsigned long bw)
 {
 	int i;
 
-	for (i = 0; i < msm_mdss->num_paths; i++)
-		icc_set_bw(msm_mdss->path[i], 0, Bps_to_icc(bw));
+	for (i = 0; i < msm_mdss->num_mdp_paths; i++)
+		icc_set_bw(msm_mdss->mdp_path[i], 0, Bps_to_icc(bw));
 }
 
 static void msm_mdss_irq(struct irq_desc *desc)

-- 
2.40.0

Re: [PATCH v2 3/5] drm/msm/mdss: Rename path references to mdp_path

[Dmitry Baryshkov]

On 18/04/2023 15:10, Konrad Dybcio wrote:
> The DPU1 driver needs to handle all MDPn<->DDR paths, as well as

Nit: msm_mdss.c is not DPU1.

> CPU<->SLAVE_DISPLAY_CFG. The former ones share how their values are
> calculated, but the latter one has static predefines spanning all SoCs.
> 
> In preparation for supporting the CPU<->SLAVE_DISPLAY_CFG path, rename
> the path-related struct members to include "mdp_".
> 
> Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
> ---
>   drivers/gpu/drm/msm/msm_mdss.c | 20 ++++++++++----------
>   1 file changed, 10 insertions(+), 10 deletions(-)

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

-- 
With best wishes
Dmitry

[PATCH v2 4/5] drm/msm/mdss: Handle the reg bus ICC path

[Konrad Dybcio]

Apart from the already handled data bus (MAS_MDP_Pn<->DDR), there's
another path that needs to be handled to ensure MDSS functions properly,
namely the "reg bus", a.k.a the CPU-MDSS interconnect.

Gating that path may have a variety of effects.. from none to otherwise
inexplicable DSI timeouts..

On the MDSS side, we only have to ensure that it's on at what Qualcomm
downstream calls "77 MHz", a.k.a 76.8 Mbps and turn it off at suspend.

To achieve that, make msm_mdss_icc_request_bw() accept a boolean to
indicate whether we want the busses to be on or off, as this function's
only use is to vote for minimum or no bandwidth at all.

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
---
 drivers/gpu/drm/msm/msm_mdss.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_mdss.c b/drivers/gpu/drm/msm/msm_mdss.c
index 9e2ce7f22677..4d126d20d661 100644
--- a/drivers/gpu/drm/msm/msm_mdss.c
+++ b/drivers/gpu/drm/msm/msm_mdss.c
@@ -50,6 +50,7 @@ struct msm_mdss {
 	const struct msm_mdss_data *mdss_data;
 	struct icc_path *mdp_path[2];
 	u32 num_mdp_paths;
+	struct icc_path *reg_bus_path;
 };
 
 static int msm_mdss_parse_data_bus_icc_path(struct device *dev,
@@ -57,6 +58,7 @@ static int msm_mdss_parse_data_bus_icc_path(struct device *dev,
 {
 	struct icc_path *path0;
 	struct icc_path *path1;
+	struct icc_path *reg_bus_path;
 
 	path0 = of_icc_get(dev, "mdp0-mem");
 	if (IS_ERR_OR_NULL(path0))
@@ -71,6 +73,10 @@ static int msm_mdss_parse_data_bus_icc_path(struct device *dev,
 		msm_mdss->num_mdp_paths++;
 	}
 
+	reg_bus_path = of_icc_get(dev, "cpu-cfg");
+	if (!IS_ERR_OR_NULL(reg_bus_path))
+		msm_mdss->reg_bus_path = reg_bus_path;
+
 	return 0;
 }
 
@@ -83,12 +89,15 @@ static void msm_mdss_put_icc_path(void *data)
 		icc_put(msm_mdss->mdp_path[i]);
 }
 
-static void msm_mdss_icc_request_bw(struct msm_mdss *msm_mdss, unsigned long bw)
+static void msm_mdss_icc_request_bw(struct msm_mdss *msm_mdss, bool enable)
 {
 	int i;
 
 	for (i = 0; i < msm_mdss->num_mdp_paths; i++)
-		icc_set_bw(msm_mdss->mdp_path[i], 0, Bps_to_icc(bw));
+		icc_set_bw(msm_mdss->mdp_path[i], 0, enable ? Bps_to_icc(MIN_IB_BW) : 0);
+
+	if (msm_mdss->reg_bus_path)
+		icc_set_bw(msm_mdss->reg_bus_path, 0, enable ? 76800 : 0);
 }
 
 static void msm_mdss_irq(struct irq_desc *desc)
@@ -241,7 +250,7 @@ static int msm_mdss_enable(struct msm_mdss *msm_mdss)
 	 * the interconnect is enabled (non-zero bandwidth). Let's make sure
 	 * that the interconnects are at least at a minimum amount.
 	 */
-	msm_mdss_icc_request_bw(msm_mdss, MIN_IB_BW);
+	msm_mdss_icc_request_bw(msm_mdss, true);
 
 	ret = clk_bulk_prepare_enable(msm_mdss->num_clocks, msm_mdss->clocks);
 	if (ret) {
@@ -289,7 +298,7 @@ static int msm_mdss_enable(struct msm_mdss *msm_mdss)
 static int msm_mdss_disable(struct msm_mdss *msm_mdss)
 {
 	clk_bulk_disable_unprepare(msm_mdss->num_clocks, msm_mdss->clocks);
-	msm_mdss_icc_request_bw(msm_mdss, 0);
+	msm_mdss_icc_request_bw(msm_mdss, false);
 
 	return 0;
 }

-- 
2.40.0

Re: [PATCH v2 4/5] drm/msm/mdss: Handle the reg bus ICC path

[Georgi Djakov]

Hi Konrad,

On 18.04.23 15:10, Konrad Dybcio wrote:
> Apart from the already handled data bus (MAS_MDP_Pn<->DDR), there's
> another path that needs to be handled to ensure MDSS functions properly,
> namely the "reg bus", a.k.a the CPU-MDSS interconnect.
> 
> Gating that path may have a variety of effects.. from none to otherwise
> inexplicable DSI timeouts..
> 
> On the MDSS side, we only have to ensure that it's on at what Qualcomm
> downstream calls "77 MHz", a.k.a 76.8 Mbps and turn it off at suspend.
> 
> To achieve that, make msm_mdss_icc_request_bw() accept a boolean to
> indicate whether we want the busses to be on or off, as this function's
> only use is to vote for minimum or no bandwidth at all.
> 
> Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
> ---
>   drivers/gpu/drm/msm/msm_mdss.c | 17 +++++++++++++----
>   1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/msm_mdss.c b/drivers/gpu/drm/msm/msm_mdss.c
[..]
> -static void msm_mdss_icc_request_bw(struct msm_mdss *msm_mdss, unsigned long bw)
> +static void msm_mdss_icc_request_bw(struct msm_mdss *msm_mdss, bool enable)
>   {
>   	int i;
>   
>   	for (i = 0; i < msm_mdss->num_mdp_paths; i++)
> -		icc_set_bw(msm_mdss->mdp_path[i], 0, Bps_to_icc(bw));
> +		icc_set_bw(msm_mdss->mdp_path[i], 0, enable ? Bps_to_icc(MIN_IB_BW) : 0);
> +
> +	if (msm_mdss->reg_bus_path)
> +		icc_set_bw(msm_mdss->reg_bus_path, 0, enable ? 76800 : 0);

Please use Bps_to_icc, kbps_to_icc or any of the other macros.

BR,
Georgi

[PATCH v2 5/5] drm/msm/dpu1: Handle the reg bus ICC path

[Konrad Dybcio]

Apart from the already handled data bus (MAS_MDP_Pn<->DDR), there's
another path that needs to be handled to ensure MDSS functions properly,
namely the "reg bus", a.k.a the CPU-MDSS interconnect.

Gating that path may have a variety of effects.. from none to otherwise
inexplicable DSI timeouts..

On the DPU side, we need to keep the bus alive. The vendor driver
kickstarts it to max (300Mbps) throughput on first commit, but in
exchange for some battery life in rare DPU-enabled-panel-disabled
usecases, we can request it at DPU init and gate it at suspend.

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 22 ++++++++++++++++++++--
 drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h |  1 +
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
index dd6c1c40ab9e..5e1ed338114d 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
@@ -384,15 +384,17 @@ static int dpu_kms_global_obj_init(struct dpu_kms *dpu_kms)
 	return 0;
 }
 
-static int dpu_kms_parse_data_bus_icc_path(struct dpu_kms *dpu_kms)
+static int dpu_kms_parse_icc_paths(struct dpu_kms *dpu_kms)
 {
 	struct icc_path *path0;
 	struct icc_path *path1;
+	struct icc_path *reg_bus_path;
 	struct drm_device *dev = dpu_kms->dev;
 	struct device *dpu_dev = dev->dev;
 
 	path0 = msm_icc_get(dpu_dev, "mdp0-mem");
 	path1 = msm_icc_get(dpu_dev, "mdp1-mem");
+	reg_bus_path = msm_icc_get(dpu_dev, "cpu-cfg");
 
 	if (IS_ERR_OR_NULL(path0))
 		return PTR_ERR_OR_ZERO(path0);
@@ -404,6 +406,10 @@ static int dpu_kms_parse_data_bus_icc_path(struct dpu_kms *dpu_kms)
 		dpu_kms->mdp_path[1] = path1;
 		dpu_kms->num_mdp_paths++;
 	}
+
+	if (!IS_ERR_OR_NULL(reg_bus_path))
+		dpu_kms->reg_bus_path = reg_bus_path;
+
 	return 0;
 }
 
@@ -1039,7 +1045,7 @@ static int dpu_kms_hw_init(struct msm_kms *kms)
 		DPU_DEBUG("REG_DMA is not defined");
 	}
 
-	dpu_kms_parse_data_bus_icc_path(dpu_kms);
+	dpu_kms_parse_icc_paths(dpu_kms);
 
 	rc = pm_runtime_resume_and_get(&dpu_kms->pdev->dev);
 	if (rc < 0)
@@ -1241,6 +1247,9 @@ static int __maybe_unused dpu_runtime_suspend(struct device *dev)
 	for (i = 0; i < dpu_kms->num_mdp_paths; i++)
 		icc_set_bw(dpu_kms->mdp_path[i], 0, 0);
 
+	if (dpu_kms->reg_bus_path)
+		icc_set_bw(dpu_kms->reg_bus_path, 0, 0);
+
 	return 0;
 }
 
@@ -1261,6 +1270,15 @@ static int __maybe_unused dpu_runtime_resume(struct device *dev)
 		return rc;
 	}
 
+	/*
+	 * The vendor driver supports setting 76.8 / 150 / 300 MBps on this
+	 * path, but it seems to go for the highest level when display output
+	 * is enabled and zero otherwise. For simplicity, we can assume that
+	 * DPU being enabled and running implies that.
+	 */
+	if (dpu_kms->reg_bus_path)
+		icc_set_bw(dpu_kms->reg_bus_path, 0, MBps_to_icc(300));
+
 	dpu_vbif_init_memtypes(dpu_kms);
 
 	drm_for_each_encoder(encoder, ddev)
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
index d5d9bec90705..c332381d58c4 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
@@ -111,6 +111,7 @@ struct dpu_kms {
 	atomic_t bandwidth_ref;
 	struct icc_path *mdp_path[2];
 	u32 num_mdp_paths;
+	struct icc_path *reg_bus_path;
 };
 
 struct vsync_info {

-- 
2.40.0