[v3] PCI: dwc: Clean up some unnecessary codes in dw_pcie_suspend_noirq()

[PATCH v3] PCI: dwc: Clean up some unnecessary codes in dw_pcie_suspend_noirq()

Posted by Richard Zhu 5 days, 2 hours ago

Before sending PME_TURN_OFF, don't test the LTSSM state. Since it's safe
to send PME_TURN_OFF message regardless of whether the link is up or
down. So, there would be no need to test the LTSSM state before sending
PME_TURN_OFF message.

Only print the message when ltssm_stat is not in DETECT and POLL.
In the other words, there isn't an error message when no endpoint is
connected at all.

Also, when the endpoint is connected and PME_TURN_OFF is sent, do not return
error if the link doesn't enter L2. Just print a warning and continue with the
suspend as the link will be recovered in dw_pcie_resume_noirq().

Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
---
v3 changes:
- Refine the commit message refer to Manivannan's comments.
- Regarding Frank's comments, avoid 10ms wait when no link up.
v2 changes:
- Don't remove L2 poll check.
- Add one 1us delay after L2 entry.
- No error return when L2 entry is timeout
- Don't print message when no link up.
---
 .../pci/controller/dwc/pcie-designware-host.c | 40 ++++++++++---------
 drivers/pci/controller/dwc/pcie-designware.h  |  1 +
 2 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 24e89b66b772..68fbc16199e8 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -927,24 +927,28 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci)
 	if (dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKCTL) & PCI_EXP_LNKCTL_ASPM_L1)
 		return 0;
 
-	/* Only send out PME_TURN_OFF when PCIE link is up */
-	if (dw_pcie_get_ltssm(pci) > DW_PCIE_LTSSM_DETECT_ACT) {
-		if (pci->pp.ops->pme_turn_off)
-			pci->pp.ops->pme_turn_off(&pci->pp);
-		else
-			ret = dw_pcie_pme_turn_off(pci);
-
-		if (ret)
-			return ret;
+	if (pci->pp.ops->pme_turn_off)
+		pci->pp.ops->pme_turn_off(&pci->pp);
+	else
+		ret = dw_pcie_pme_turn_off(pci);
+	if (ret)
+		return ret;
 
-		ret = read_poll_timeout(dw_pcie_get_ltssm, val, val == DW_PCIE_LTSSM_L2_IDLE,
-					PCIE_PME_TO_L2_TIMEOUT_US/10,
-					PCIE_PME_TO_L2_TIMEOUT_US, false, pci);
-		if (ret) {
-			dev_err(pci->dev, "Timeout waiting for L2 entry! LTSSM: 0x%x\n", val);
-			return ret;
-		}
-	}
+	ret = read_poll_timeout(dw_pcie_get_ltssm, val,
+				val == DW_PCIE_LTSSM_L2_IDLE ||
+				val <= DW_PCIE_LTSSM_DETECT_WAIT,
+				PCIE_PME_TO_L2_TIMEOUT_US/10,
+				PCIE_PME_TO_L2_TIMEOUT_US, false, pci);
+	if (ret && (val > DW_PCIE_LTSSM_DETECT_WAIT))
+		/* Only dump message when ltssm_stat isn't in DETECT and POLL */
+		dev_warn(pci->dev, "Timeout waiting for L2 entry! LTSSM: 0x%x\n", val);
+	else
+		/*
+		 * Refer to r6.0, sec 5.3.3.2.1, software should wait at least
+		 * 100ns after L2/L3 Ready before turning off refclock and
+		 * main power. It's harmless too when no endpoint connected.
+		 */
+		udelay(1);
 
 	dw_pcie_stop_link(pci);
 	if (pci->pp.ops->deinit)
@@ -952,7 +956,7 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci)
 
 	pci->suspended = true;
 
-	return ret;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(dw_pcie_suspend_noirq);
 
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 347ab74ac35a..bf036e66717e 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -330,6 +330,7 @@ enum dw_pcie_ltssm {
 	/* Need to align with PCIE_PORT_DEBUG0 bits 0:5 */
 	DW_PCIE_LTSSM_DETECT_QUIET = 0x0,
 	DW_PCIE_LTSSM_DETECT_ACT = 0x1,
+	DW_PCIE_LTSSM_DETECT_WAIT = 0x6,
 	DW_PCIE_LTSSM_L0 = 0x11,
 	DW_PCIE_LTSSM_L2_IDLE = 0x15,
 
-- 
2.37.1

Re: [PATCH v3] PCI: dwc: Clean up some unnecessary codes in dw_pcie_suspend_noirq()

Posted by Frank Li 3 days, 14 hours ago

On Mon, Nov 18, 2024 at 01:44:47PM +0800, Richard Zhu wrote:
> Before sending PME_TURN_OFF, don't test the LTSSM state. Since it's safe
> to send PME_TURN_OFF message regardless of whether the link is up or
> down. So, there would be no need to test the LTSSM state before sending
> PME_TURN_OFF message.
>
> Only print the message when ltssm_stat is not in DETECT and POLL.
> In the other words, there isn't an error message when no endpoint is
> connected at all.
>
> Also, when the endpoint is connected and PME_TURN_OFF is sent, do not return
> error if the link doesn't enter L2. Just print a warning and continue with the
> suspend as the link will be recovered in dw_pcie_resume_noirq().
>
> Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
> ---
> v3 changes:
> - Refine the commit message refer to Manivannan's comments.
> - Regarding Frank's comments, avoid 10ms wait when no link up.
> v2 changes:
> - Don't remove L2 poll check.
> - Add one 1us delay after L2 entry.
> - No error return when L2 entry is timeout
> - Don't print message when no link up.
> ---
>  .../pci/controller/dwc/pcie-designware-host.c | 40 ++++++++++---------
>  drivers/pci/controller/dwc/pcie-designware.h  |  1 +
>  2 files changed, 23 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 24e89b66b772..68fbc16199e8 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -927,24 +927,28 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci)
>  	if (dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKCTL) & PCI_EXP_LNKCTL_ASPM_L1)
>  		return 0;
>
> -	/* Only send out PME_TURN_OFF when PCIE link is up */
> -	if (dw_pcie_get_ltssm(pci) > DW_PCIE_LTSSM_DETECT_ACT) {
> -		if (pci->pp.ops->pme_turn_off)
> -			pci->pp.ops->pme_turn_off(&pci->pp);
> -		else
> -			ret = dw_pcie_pme_turn_off(pci);
> -
> -		if (ret)
> -			return ret;
> +	if (pci->pp.ops->pme_turn_off)
> +		pci->pp.ops->pme_turn_off(&pci->pp);
> +	else
> +		ret = dw_pcie_pme_turn_off(pci);
> +	if (ret)
> +		return ret;
>
> -		ret = read_poll_timeout(dw_pcie_get_ltssm, val, val == DW_PCIE_LTSSM_L2_IDLE,
> -					PCIE_PME_TO_L2_TIMEOUT_US/10,
> -					PCIE_PME_TO_L2_TIMEOUT_US, false, pci);
> -		if (ret) {
> -			dev_err(pci->dev, "Timeout waiting for L2 entry! LTSSM: 0x%x\n", val);
> -			return ret;
> -		}
> -	}
> +	ret = read_poll_timeout(dw_pcie_get_ltssm, val,
> +				val == DW_PCIE_LTSSM_L2_IDLE ||
> +				val <= DW_PCIE_LTSSM_DETECT_WAIT,
> +				PCIE_PME_TO_L2_TIMEOUT_US/10,
> +				PCIE_PME_TO_L2_TIMEOUT_US, false, pci);
> +	if (ret && (val > DW_PCIE_LTSSM_DETECT_WAIT))

if true of (val <= DW_PCIE_LTSSM_DETECT_WAIT), which means not device
attached, 'ret' should be 0.

when ret is not 0, means, link up and not in L2 idle status. So check
'(val > DW_PCIE_LTSSM_DETECT_WAIT)' is redundant.

NOT(val == DW_PCIE_LTSSM_L2_IDLE || val <= DW_PCIE_LTSSM_DETECT_WAIT)
equal
(val != DW_PCIE_LTSSM_L2_IDLE) && (val > DW_PCIE_LTSSM_DETECT_WAIT)

Frank

> +		/* Only dump message when ltssm_stat isn't in DETECT and POLL */
> +		dev_warn(pci->dev, "Timeout waiting for L2 entry! LTSSM: 0x%x\n", val);
> +	else
> +		/*
> +		 * Refer to r6.0, sec 5.3.3.2.1, software should wait at least
> +		 * 100ns after L2/L3 Ready before turning off refclock and
> +		 * main power. It's harmless too when no endpoint connected.
> +		 */
> +		udelay(1);
>
>  	dw_pcie_stop_link(pci);
>  	if (pci->pp.ops->deinit)
> @@ -952,7 +956,7 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci)
>
>  	pci->suspended = true;
>
> -	return ret;
> +	return 0;
>  }
>  EXPORT_SYMBOL_GPL(dw_pcie_suspend_noirq);
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 347ab74ac35a..bf036e66717e 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -330,6 +330,7 @@ enum dw_pcie_ltssm {
>  	/* Need to align with PCIE_PORT_DEBUG0 bits 0:5 */
>  	DW_PCIE_LTSSM_DETECT_QUIET = 0x0,
>  	DW_PCIE_LTSSM_DETECT_ACT = 0x1,
> +	DW_PCIE_LTSSM_DETECT_WAIT = 0x6,
>  	DW_PCIE_LTSSM_L0 = 0x11,
>  	DW_PCIE_LTSSM_L2_IDLE = 0x15,
>
> --
> 2.37.1
>

Re: [PATCH v3] PCI: dwc: Clean up some unnecessary codes in dw_pcie_suspend_noirq()

Posted by Krishna Chaitanya Chundru 5 days, 1 hour ago


On 11/18/2024 11:14 AM, Richard Zhu wrote:
> Before sending PME_TURN_OFF, don't test the LTSSM state. Since it's safe
> to send PME_TURN_OFF message regardless of whether the link is up or
> down. So, there would be no need to test the LTSSM state before sending
> PME_TURN_OFF message.
> 
> Only print the message when ltssm_stat is not in DETECT and POLL.
> In the other words, there isn't an error message when no endpoint is
> connected at all.
> 
> Also, when the endpoint is connected and PME_TURN_OFF is sent, do not return
> error if the link doesn't enter L2. Just print a warning and continue with the
> suspend as the link will be recovered in dw_pcie_resume_noirq().
> 
> Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
> ---
> v3 changes:
> - Refine the commit message refer to Manivannan's comments.
> - Regarding Frank's comments, avoid 10ms wait when no link up.
> v2 changes:
> - Don't remove L2 poll check.
> - Add one 1us delay after L2 entry.
> - No error return when L2 entry is timeout
> - Don't print message when no link up.
> ---
>   .../pci/controller/dwc/pcie-designware-host.c | 40 ++++++++++---------
>   drivers/pci/controller/dwc/pcie-designware.h  |  1 +
>   2 files changed, 23 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 24e89b66b772..68fbc16199e8 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -927,24 +927,28 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci)
>   	if (dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKCTL) & PCI_EXP_LNKCTL_ASPM_L1)
>   		return 0;
>   
> -	/* Only send out PME_TURN_OFF when PCIE link is up */
> -	if (dw_pcie_get_ltssm(pci) > DW_PCIE_LTSSM_DETECT_ACT) {
> -		if (pci->pp.ops->pme_turn_off)
> -			pci->pp.ops->pme_turn_off(&pci->pp);
> -		else
> -			ret = dw_pcie_pme_turn_off(pci);
> -
> -		if (ret)
> -			return ret;
> +	if (pci->pp.ops->pme_turn_off)
> +		pci->pp.ops->pme_turn_off(&pci->pp);
> +	else
> +		ret = dw_pcie_pme_turn_off(pci);
> +	if (ret)
> +		return ret;
>   
> -		ret = read_poll_timeout(dw_pcie_get_ltssm, val, val == DW_PCIE_LTSSM_L2_IDLE,
> -					PCIE_PME_TO_L2_TIMEOUT_US/10,
> -					PCIE_PME_TO_L2_TIMEOUT_US, false, pci);
> -		if (ret) {
> -			dev_err(pci->dev, "Timeout waiting for L2 entry! LTSSM: 0x%x\n", val);
> -			return ret;
> -		}
> -	}
> +	ret = read_poll_timeout(dw_pcie_get_ltssm, val,
> +				val == DW_PCIE_LTSSM_L2_IDLE ||
> +				val <= DW_PCIE_LTSSM_DETECT_WAIT,
> +				PCIE_PME_TO_L2_TIMEOUT_US/10,
> +				PCIE_PME_TO_L2_TIMEOUT_US, false, pci);
> +	if (ret && (val > DW_PCIE_LTSSM_DETECT_WAIT))
> +		/* Only dump message when ltssm_stat isn't in DETECT and POLL */
> +		dev_warn(pci->dev, "Timeout waiting for L2 entry! LTSSM: 0x%x\n", val);
we need to return ret here in case we fail to enter L2 when the endpoint 
is connected.

- Krishna Chaitanya.
> +	else
> +		/*
> +		 * Refer to r6.0, sec 5.3.3.2.1, software should wait at least
> +		 * 100ns after L2/L3 Ready before turning off refclock and
> +		 * main power. It's harmless too when no endpoint connected.
> +		 */
> +		udelay(1);
>   
>   	dw_pcie_stop_link(pci);
>   	if (pci->pp.ops->deinit)
> @@ -952,7 +956,7 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci)
>   
>   	pci->suspended = true;
>   
> -	return ret;
> +	return 0;
>   }
>   EXPORT_SYMBOL_GPL(dw_pcie_suspend_noirq);
>   
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 347ab74ac35a..bf036e66717e 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -330,6 +330,7 @@ enum dw_pcie_ltssm {
>   	/* Need to align with PCIE_PORT_DEBUG0 bits 0:5 */
>   	DW_PCIE_LTSSM_DETECT_QUIET = 0x0,
>   	DW_PCIE_LTSSM_DETECT_ACT = 0x1,
> +	DW_PCIE_LTSSM_DETECT_WAIT = 0x6,
>   	DW_PCIE_LTSSM_L0 = 0x11,
>   	DW_PCIE_LTSSM_L2_IDLE = 0x15,
>