diff mbox series

[v10,2/6] PCI: qcom: Add ICC bandwidth vote for CPU to PCIe path

Message ID 20240409-opp_support-v10-2-1956e6be343f@quicinc.com
State Superseded
Headers show
Series PCI: qcom: Add support for OPP | expand

Commit Message

Krishna Chaitanya Chundru April 9, 2024, 10:13 a.m. UTC 
To access PCIe registers of the host controller and endpoint PCIe
BAR space, config space the CPU-PCIe ICC (interconnect) path should
be voted otherwise it may lead to NoC (Network on chip) timeout.
We are surviving because of other driver voting for this path.

As there is less access on this path compared to PCIe to mem path
add minimum vote i.e 1KBps bandwidth always which is sufficient enough
to keep the path active and is recommended by HW team.

In suspend to ram case there can be some DBI access. Except in suspend
to ram case disable CPU-PCIe ICC path after register space access
is done.

Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 43 ++++++++++++++++++++++++++++++----
 1 file changed, 39 insertions(+), 4 deletions(-)

Comments

Manivannan Sadhasivam April 22, 2024, 2:31 p.m. UTC | #1 
On Tue, Apr 09, 2024 at 03:43:20PM +0530, Krishna chaitanya chundru wrote:
> To access PCIe registers of the host controller and endpoint PCIe
> BAR space, config space the CPU-PCIe ICC (interconnect) path should

'To access the host controller registers and endpoint BAR/Config space,'

> be voted otherwise it may lead to NoC (Network on chip) timeout.
> We are surviving because of other driver voting for this path.
> 
> As there is less access on this path compared to PCIe to mem path
> add minimum vote i.e 1KBps bandwidth always which is sufficient enough
> to keep the path active and is recommended by HW team.
> 
> In suspend to ram case there can be some DBI access. Except in suspend
> to ram case disable CPU-PCIe ICC path after register space access
> is done.
> 

During S2RAM (Suspend-to-RAM), DBI access can happen very late (while disabling
the boot CPU). So do not disable the CPU-PCIe interconnect path during S2RAM as
that may lead to NoC error.

> Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
> Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
> ---
>  drivers/pci/controller/dwc/pcie-qcom.c | 43 ++++++++++++++++++++++++++++++----
>  1 file changed, 39 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index 14772edcf0d3..e53422171c01 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -245,6 +245,7 @@ struct qcom_pcie {
>  	struct phy *phy;
>  	struct gpio_desc *reset;
>  	struct icc_path *icc_mem;
> +	struct icc_path *icc_cpu;
>  	const struct qcom_pcie_cfg *cfg;
>  	struct dentry *debugfs;
>  	bool suspended;
> @@ -1409,6 +1410,9 @@ static int qcom_pcie_icc_init(struct qcom_pcie *pcie)
>  	if (IS_ERR(pcie->icc_mem))
>  		return PTR_ERR(pcie->icc_mem);
>  
> +	pcie->icc_cpu = devm_of_icc_get(pci->dev, "cpu-pcie");
> +	if (IS_ERR(pcie->icc_cpu))
> +		return PTR_ERR(pcie->icc_cpu);
>  	/*
>  	 * Some Qualcomm platforms require interconnect bandwidth constraints
>  	 * to be set before enabling interconnect clocks.
> @@ -1418,7 +1422,20 @@ static int qcom_pcie_icc_init(struct qcom_pcie *pcie)
>  	 */
>  	ret = icc_set_bw(pcie->icc_mem, 0, QCOM_PCIE_LINK_SPEED_TO_BW(1));
>  	if (ret) {
> -		dev_err(pci->dev, "failed to set interconnect bandwidth: %d\n",
> +		dev_err(pci->dev, "Failed to set interconnect bandwidth for PCIe-MEM: %d\n",

'Failed to set bandwidth for PCIe-MEM interconnect path: %d\n'

> +			ret);
> +		return ret;
> +	}
> +
> +	/*
> +	 * Since the CPU-PCIe path is only used for activities like register
> +	 * access of the host controller and endpoint Config/BAR space access,
> +	 * HW team has recommended to use a  minimal bandwidth of 1KBps just to

Single space after 'a'

> +	 * keep the path active.
> +	 */
> +	ret = icc_set_bw(pcie->icc_cpu, 0, kBps_to_icc(1));
> +	if (ret) {
> +		dev_err(pci->dev, "Failed to set interconnect bandwidth for CPU-PCIe: %d\n",

'Failed to set bandwidth for CPU-PCIe interconnect path: %d\n'

>  			ret);
>  		return ret;
>  	}
> @@ -1448,7 +1465,7 @@ static void qcom_pcie_icc_update(struct qcom_pcie *pcie)
>  
>  	ret = icc_set_bw(pcie->icc_mem, 0, width * QCOM_PCIE_LINK_SPEED_TO_BW(speed));
>  	if (ret) {
> -		dev_err(pci->dev, "failed to set interconnect bandwidth: %d\n",
> +		dev_err(pci->dev, "Failed to set interconnect bandwidth for PCIe-MEM: %d\n",

'Failed to set bandwidth for PCIe-MEM interconnect path: %d\n'

>  			ret);
>  	}
>  }
> @@ -1610,7 +1627,7 @@ static int qcom_pcie_suspend_noirq(struct device *dev)
>  	 */
>  	ret = icc_set_bw(pcie->icc_mem, 0, kBps_to_icc(1));
>  	if (ret) {
> -		dev_err(dev, "Failed to set interconnect bandwidth: %d\n", ret);
> +		dev_err(dev, "Failed to set interconnect bandwidth for PCIe-MEM: %d\n", ret);

'Failed to set bandwidth for PCIe-MEM interconnect path: %d\n'

>  		return ret;
>  	}
>  
> @@ -1634,7 +1651,17 @@ static int qcom_pcie_suspend_noirq(struct device *dev)
>  		pcie->suspended = true;
>  	}
>  
> -	return 0;
> +	/*
> +	 * In suspend to ram case there are DBI access, except in suspend to ram case
> +	 * remove the vote for CPU-PCIe path now, since at this point onwards,
> +	 * no register access will be done.
> +	 */

	/*
	 * Only disable CPU-PCIe interconnect path if the suspend is non-S2RAM.
	 * Because on some platforms, DBI access can happen very late during the
	 * S2RAM and a non-active CPU-PCIe interconnect path may lead to NoC
	 * error.
	 */

> +	if (pm_suspend_target_state != PM_SUSPEND_MEM) {
> +		ret = icc_disable(pcie->icc_cpu);
> +		if (ret)
> +			dev_err(dev, "Failed to disable Interconnect path of CPU-PCIe: %d\n", ret);

'Failed to disable CPU-PCIe interconnect path: %d\n'

> +	}
> +	return ret;
>  }
>  
>  static int qcom_pcie_resume_noirq(struct device *dev)
> @@ -1642,6 +1669,14 @@ static int qcom_pcie_resume_noirq(struct device *dev)
>  	struct qcom_pcie *pcie = dev_get_drvdata(dev);
>  	int ret;
>  
> +	if (pm_suspend_target_state != PM_SUSPEND_MEM) {
> +		ret = icc_enable(pcie->icc_cpu);
> +		if (ret) {
> +			dev_err(dev, "Failed to enable Interconnect path of CPU-PCIe: %d\n", ret);

'Failed to enable CPU-PCIe interconnect path: %d\n'

- Mani
diff mbox series

Patch

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 14772edcf0d3..e53422171c01 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -245,6 +245,7 @@  struct qcom_pcie {
 	struct phy *phy;
 	struct gpio_desc *reset;
 	struct icc_path *icc_mem;
+	struct icc_path *icc_cpu;
 	const struct qcom_pcie_cfg *cfg;
 	struct dentry *debugfs;
 	bool suspended;
@@ -1409,6 +1410,9 @@  static int qcom_pcie_icc_init(struct qcom_pcie *pcie)
 	if (IS_ERR(pcie->icc_mem))
 		return PTR_ERR(pcie->icc_mem);
 
+	pcie->icc_cpu = devm_of_icc_get(pci->dev, "cpu-pcie");
+	if (IS_ERR(pcie->icc_cpu))
+		return PTR_ERR(pcie->icc_cpu);
 	/*
 	 * Some Qualcomm platforms require interconnect bandwidth constraints
 	 * to be set before enabling interconnect clocks.
@@ -1418,7 +1422,20 @@  static int qcom_pcie_icc_init(struct qcom_pcie *pcie)
 	 */
 	ret = icc_set_bw(pcie->icc_mem, 0, QCOM_PCIE_LINK_SPEED_TO_BW(1));
 	if (ret) {
-		dev_err(pci->dev, "failed to set interconnect bandwidth: %d\n",
+		dev_err(pci->dev, "Failed to set interconnect bandwidth for PCIe-MEM: %d\n",
+			ret);
+		return ret;
+	}
+
+	/*
+	 * Since the CPU-PCIe path is only used for activities like register
+	 * access of the host controller and endpoint Config/BAR space access,
+	 * HW team has recommended to use a  minimal bandwidth of 1KBps just to
+	 * keep the path active.
+	 */
+	ret = icc_set_bw(pcie->icc_cpu, 0, kBps_to_icc(1));
+	if (ret) {
+		dev_err(pci->dev, "Failed to set interconnect bandwidth for CPU-PCIe: %d\n",
 			ret);
 		return ret;
 	}
@@ -1448,7 +1465,7 @@  static void qcom_pcie_icc_update(struct qcom_pcie *pcie)
 
 	ret = icc_set_bw(pcie->icc_mem, 0, width * QCOM_PCIE_LINK_SPEED_TO_BW(speed));
 	if (ret) {
-		dev_err(pci->dev, "failed to set interconnect bandwidth: %d\n",
+		dev_err(pci->dev, "Failed to set interconnect bandwidth for PCIe-MEM: %d\n",
 			ret);
 	}
 }
@@ -1610,7 +1627,7 @@  static int qcom_pcie_suspend_noirq(struct device *dev)
 	 */
 	ret = icc_set_bw(pcie->icc_mem, 0, kBps_to_icc(1));
 	if (ret) {
-		dev_err(dev, "Failed to set interconnect bandwidth: %d\n", ret);
+		dev_err(dev, "Failed to set interconnect bandwidth for PCIe-MEM: %d\n", ret);
 		return ret;
 	}
 
@@ -1634,7 +1651,17 @@  static int qcom_pcie_suspend_noirq(struct device *dev)
 		pcie->suspended = true;
 	}
 
-	return 0;
+	/*
+	 * In suspend to ram case there are DBI access, except in suspend to ram case
+	 * remove the vote for CPU-PCIe path now, since at this point onwards,
+	 * no register access will be done.
+	 */
+	if (pm_suspend_target_state != PM_SUSPEND_MEM) {
+		ret = icc_disable(pcie->icc_cpu);
+		if (ret)
+			dev_err(dev, "Failed to disable Interconnect path of CPU-PCIe: %d\n", ret);
+	}
+	return ret;
 }
 
 static int qcom_pcie_resume_noirq(struct device *dev)
@@ -1642,6 +1669,14 @@  static int qcom_pcie_resume_noirq(struct device *dev)
 	struct qcom_pcie *pcie = dev_get_drvdata(dev);
 	int ret;
 
+	if (pm_suspend_target_state != PM_SUSPEND_MEM) {
+		ret = icc_enable(pcie->icc_cpu);
+		if (ret) {
+			dev_err(dev, "Failed to enable Interconnect path of CPU-PCIe: %d\n", ret);
+			return ret;
+		}
+	}
+
 	if (pcie->suspended) {
 		ret = qcom_pcie_host_init(&pcie->pci->pp);
 		if (ret)