From: Qiang Yu <quic_qianyu@quicinc.com>

Some QCOM PCIe PHYs support no_csr reset. Unlike BCR reset which resets the
whole PHY (hardware and register), no_csr reset only resets PHY hardware
but retains register values, which means PHY setting can be skipped during
PHY init if PCIe link is enabled in booltloader and only no_csr is toggled
after that.

Hence, determine whether the PHY has been enabled in bootloader by
verifying QPHY_START_CTRL register. If it's programmed and no_csr reset is
available, skip BCR reset and PHY register setting to establish the PCIe
link with bootloader - programmed PHY settings.

Signed-off-by: Qiang Yu <quic_qianyu@quicinc.com>
Signed-off-by: Wenbin Yao <quic_wenbyao@quicinc.com>
---
 drivers/phy/qualcomm/phy-qcom-qmp-pcie.c | 69 ++++++++++++++++++++----
 1 file changed, 59 insertions(+), 10 deletions(-)

diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
index 219266125cf2..c3642d1807e4 100644
--- a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
+++ b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
@@ -2805,6 +2805,7 @@ struct qmp_pcie {
 
 	const struct qmp_phy_cfg *cfg;
 	bool tcsr_4ln_config;
+	bool skip_init;
 
 	void __iomem *serdes;
 	void __iomem *pcs;
@@ -3976,18 +3977,38 @@ static int qmp_pcie_init(struct phy *phy)
 {
 	struct qmp_pcie *qmp = phy_get_drvdata(phy);
 	const struct qmp_phy_cfg *cfg = qmp->cfg;
+	void __iomem *pcs = qmp->pcs;
+	bool phy_initialized = !!(readl(pcs + cfg->regs[QPHY_START_CTRL]));
 	int ret;
 
+	qmp->skip_init = qmp->nocsr_reset && phy_initialized;
+	/*
+	 * We need to check the existence of init sequences in two cases:
+	 * 1. The PHY doesn't support no_csr reset.
+	 * 2. The PHY supports no_csr reset but isn't initialized by bootloader.
+	 * As we can't skip init in these two cases.
+	 */
+	if (!qmp->skip_init && !cfg->tbls.serdes_num) {
+		dev_err(qmp->dev, "no init sequences are available\n");
+		return -EINVAL;
+	}
+
 	ret = regulator_bulk_enable(cfg->num_vregs, qmp->vregs);
 	if (ret) {
 		dev_err(qmp->dev, "failed to enable regulators, err=%d\n", ret);
 		return ret;
 	}
 
-	ret = reset_control_bulk_assert(cfg->num_resets, qmp->resets);
-	if (ret) {
-		dev_err(qmp->dev, "reset assert failed\n");
-		goto err_disable_regulators;
+	/*
+	 * Toggle BCR reset for PHY that doesn't support no_csr reset or has not
+	 * been initialized.
+	 */
+	if (!qmp->skip_init) {
+		ret = reset_control_bulk_assert(cfg->num_resets, qmp->resets);
+		if (ret) {
+			dev_err(qmp->dev, "reset assert failed\n");
+			goto err_disable_regulators;
+		}
 	}
 
 	ret = reset_control_assert(qmp->nocsr_reset);
@@ -3998,10 +4019,12 @@ static int qmp_pcie_init(struct phy *phy)
 
 	usleep_range(200, 300);
 
-	ret = reset_control_bulk_deassert(cfg->num_resets, qmp->resets);
-	if (ret) {
-		dev_err(qmp->dev, "reset deassert failed\n");
-		goto err_assert_reset;
+	if (!qmp->skip_init) {
+		ret = reset_control_bulk_deassert(cfg->num_resets, qmp->resets);
+		if (ret) {
+			dev_err(qmp->dev, "reset deassert failed\n");
+			goto err_assert_reset;
+		}
 	}
 
 	ret = clk_bulk_prepare_enable(ARRAY_SIZE(qmp_pciephy_clk_l), qmp->clks);
@@ -4011,7 +4034,8 @@ static int qmp_pcie_init(struct phy *phy)
 	return 0;
 
 err_assert_reset:
-	reset_control_bulk_assert(cfg->num_resets, qmp->resets);
+	if (!qmp->skip_init)
+		reset_control_bulk_assert(cfg->num_resets, qmp->resets);
 err_disable_regulators:
 	regulator_bulk_disable(cfg->num_vregs, qmp->vregs);
 
@@ -4023,7 +4047,10 @@ static int qmp_pcie_exit(struct phy *phy)
 	struct qmp_pcie *qmp = phy_get_drvdata(phy);
 	const struct qmp_phy_cfg *cfg = qmp->cfg;
 
-	reset_control_bulk_assert(cfg->num_resets, qmp->resets);
+	if (qmp->nocsr_reset)
+		reset_control_assert(qmp->nocsr_reset);
+	else
+		reset_control_bulk_assert(cfg->num_resets, qmp->resets);
 
 	clk_bulk_disable_unprepare(ARRAY_SIZE(qmp_pciephy_clk_l), qmp->clks);
 
@@ -4042,6 +4069,13 @@ static int qmp_pcie_power_on(struct phy *phy)
 	unsigned int mask, val;
 	int ret;
 
+	/*
+	 * Write CSR register for PHY that doesn't support no_csr reset or has not
+	 * been initialized.
+	 */
+	if (qmp->skip_init)
+		goto skip_tbls_init;
+
 	qphy_setbits(pcs, cfg->regs[QPHY_PCS_POWER_DOWN_CONTROL],
 			cfg->pwrdn_ctrl);
 
@@ -4053,6 +4087,7 @@ static int qmp_pcie_power_on(struct phy *phy)
 	qmp_pcie_init_registers(qmp, &cfg->tbls);
 	qmp_pcie_init_registers(qmp, mode_tbls);
 
+skip_tbls_init:
 	ret = clk_bulk_prepare_enable(qmp->num_pipe_clks, qmp->pipe_clks);
 	if (ret)
 		return ret;
@@ -4063,6 +4098,9 @@ static int qmp_pcie_power_on(struct phy *phy)
 		goto err_disable_pipe_clk;
 	}
 
+	if (qmp->skip_init)
+		goto skip_serdes_start;
+
 	/* Pull PHY out of reset state */
 	qphy_clrbits(pcs, cfg->regs[QPHY_SW_RESET], SW_RESET);
 
@@ -4072,6 +4110,7 @@ static int qmp_pcie_power_on(struct phy *phy)
 	if (!cfg->skip_start_delay)
 		usleep_range(1000, 1200);
 
+skip_serdes_start:
 	status = pcs + cfg->regs[QPHY_PCS_STATUS];
 	mask = cfg->phy_status;
 	ret = readl_poll_timeout(status, val, !(val & mask), 200,
@@ -4096,6 +4135,15 @@ static int qmp_pcie_power_off(struct phy *phy)
 
 	clk_bulk_disable_unprepare(qmp->num_pipe_clks, qmp->pipe_clks);
 
+	/*
+	 * While powering off the PHY, only qmp->nocsr_reset needs to be checked. In
+	 * this way, no matter whether the PHY settings were initially programmed by
+	 * bootloader or PHY driver itself, we can reuse them when PHY is powered on
+	 * next time.
+	 */
+	if (qmp->nocsr_reset)
+		goto skip_phy_deinit;
+
 	/* PHY reset */
 	qphy_setbits(qmp->pcs, cfg->regs[QPHY_SW_RESET], SW_RESET);
 
@@ -4107,6 +4155,7 @@ static int qmp_pcie_power_off(struct phy *phy)
 	qphy_clrbits(qmp->pcs, cfg->regs[QPHY_PCS_POWER_DOWN_CONTROL],
 			cfg->pwrdn_ctrl);
 
+skip_phy_deinit:
 	return 0;
 }
 
-- 
2.34.1

On Wed, Feb 26, 2025 at 06:36:00PM +0800, Wenbin Yao wrote:
> From: Qiang Yu <quic_qianyu@quicinc.com>
> 
> Some QCOM PCIe PHYs support no_csr reset. Unlike BCR reset which resets the
> whole PHY (hardware and register), no_csr reset only resets PHY hardware
> but retains register values, which means PHY setting can be skipped during
> PHY init if PCIe link is enabled in booltloader and only no_csr is toggled
> after that.
> 
> Hence, determine whether the PHY has been enabled in bootloader by
> verifying QPHY_START_CTRL register. If it's programmed and no_csr reset is
> available, skip BCR reset and PHY register setting to establish the PCIe
> link with bootloader - programmed PHY settings.
> 
> Signed-off-by: Qiang Yu <quic_qianyu@quicinc.com>
> Signed-off-by: Wenbin Yao <quic_wenbyao@quicinc.com>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

One nit below.

> ---
>  drivers/phy/qualcomm/phy-qcom-qmp-pcie.c | 69 ++++++++++++++++++++----
>  1 file changed, 59 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
> index 219266125cf2..c3642d1807e4 100644
> --- a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
> +++ b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
> @@ -2805,6 +2805,7 @@ struct qmp_pcie {
>  
>  	const struct qmp_phy_cfg *cfg;
>  	bool tcsr_4ln_config;
> +	bool skip_init;
>  
>  	void __iomem *serdes;
>  	void __iomem *pcs;
> @@ -3976,18 +3977,38 @@ static int qmp_pcie_init(struct phy *phy)
>  {
>  	struct qmp_pcie *qmp = phy_get_drvdata(phy);
>  	const struct qmp_phy_cfg *cfg = qmp->cfg;
> +	void __iomem *pcs = qmp->pcs;
> +	bool phy_initialized = !!(readl(pcs + cfg->regs[QPHY_START_CTRL]));
>  	int ret;
>  
> +	qmp->skip_init = qmp->nocsr_reset && phy_initialized;
> +	/*
> +	 * We need to check the existence of init sequences in two cases:
> +	 * 1. The PHY doesn't support no_csr reset.
> +	 * 2. The PHY supports no_csr reset but isn't initialized by bootloader.
> +	 * As we can't skip init in these two cases.
> +	 */
> +	if (!qmp->skip_init && !cfg->tbls.serdes_num) {
> +		dev_err(qmp->dev, "no init sequences are available\n");

"Init sequence not available\n"

> +		return -EINVAL;

-ENODATA

- Mani

-- 
மணிவண்ணன் சதாசிவம்

On 3/14/2025 10:50 PM, Manivannan Sadhasivam wrote:
> On Wed, Feb 26, 2025 at 06:36:00PM +0800, Wenbin Yao wrote:
>> From: Qiang Yu <quic_qianyu@quicinc.com>
>>
>> Some QCOM PCIe PHYs support no_csr reset. Unlike BCR reset which resets the
>> whole PHY (hardware and register), no_csr reset only resets PHY hardware
>> but retains register values, which means PHY setting can be skipped during
>> PHY init if PCIe link is enabled in booltloader and only no_csr is toggled
>> after that.
>>
>> Hence, determine whether the PHY has been enabled in bootloader by
>> verifying QPHY_START_CTRL register. If it's programmed and no_csr reset is
>> available, skip BCR reset and PHY register setting to establish the PCIe
>> link with bootloader - programmed PHY settings.
>>
>> Signed-off-by: Qiang Yu <quic_qianyu@quicinc.com>
>> Signed-off-by: Wenbin Yao <quic_wenbyao@quicinc.com>
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
>
> One nit below.
>
>> ---
>>   drivers/phy/qualcomm/phy-qcom-qmp-pcie.c | 69 ++++++++++++++++++++----
>>   1 file changed, 59 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
>> index 219266125cf2..c3642d1807e4 100644
>> --- a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
>> +++ b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
>> @@ -2805,6 +2805,7 @@ struct qmp_pcie {
>>   
>>   	const struct qmp_phy_cfg *cfg;
>>   	bool tcsr_4ln_config;
>> +	bool skip_init;
>>   
>>   	void __iomem *serdes;
>>   	void __iomem *pcs;
>> @@ -3976,18 +3977,38 @@ static int qmp_pcie_init(struct phy *phy)
>>   {
>>   	struct qmp_pcie *qmp = phy_get_drvdata(phy);
>>   	const struct qmp_phy_cfg *cfg = qmp->cfg;
>> +	void __iomem *pcs = qmp->pcs;
>> +	bool phy_initialized = !!(readl(pcs + cfg->regs[QPHY_START_CTRL]));
>>   	int ret;
>>   
>> +	qmp->skip_init = qmp->nocsr_reset && phy_initialized;
>> +	/*
>> +	 * We need to check the existence of init sequences in two cases:
>> +	 * 1. The PHY doesn't support no_csr reset.
>> +	 * 2. The PHY supports no_csr reset but isn't initialized by bootloader.
>> +	 * As we can't skip init in these two cases.
>> +	 */
>> +	if (!qmp->skip_init && !cfg->tbls.serdes_num) {
>> +		dev_err(qmp->dev, "no init sequences are available\n");
> "Init sequence not available\n"
>
>> +		return -EINVAL;
> -ENODATA

Will fix in the next version.

>
> - Mani
>
-- 
With best wishes
Wenbin