diff mbox series

[v1,1/5] PCI: imx6: Start link directly when workaround is not required

Message ID 20250324062647.1891896-2-hongxing.zhu@nxp.com (mailing list archive)
State Superseded
Delegated to: Krzysztof Wilczyński
Headers show
Series Add some enhancements for i.MX95 PCIe | expand

Commit Message

Richard Zhu March 24, 2025, 6:26 a.m. UTC 
The current link setup procedure is more like one workaround to detect
the device behind PCIe switches on some i.MX6 platforms.

To describe more accurately, change the flag name from
IMX_PCIE_FLAG_IMX_SPEED_CHANGE to IMX_PCIE_FLAG_SPEED_CHANGE_WORKAROUND.

Then, start PCIe link directly when this flag is not set on i.MX7 or
later paltforms to simple and speed up link training.

Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
---
 drivers/pci/controller/dwc/pci-imx6.c | 34 +++++++++++----------------
 1 file changed, 14 insertions(+), 20 deletions(-)

Comments

Richard Zhu March 24, 2025, 7:48 a.m. UTC | #1 
> -----Original Message-----
> From: Hongxing Zhu <hongxing.zhu@nxp.com>
> Sent: 2025年3月24日 14:27
> To: Frank Li <frank.li@nxp.com>; l.stach@pengutronix.de;
> lpieralisi@kernel.org; kw@linux.com; manivannan.sadhasivam@linaro.org;
> robh@kernel.org; bhelgaas@google.com; shawnguo@kernel.org;
> s.hauer@pengutronix.de; kernel@pengutronix.de; festevam@gmail.com
> Cc: linux-pci@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> imx@lists.linux.dev; linux-kernel@vger.kernel.org; Hongxing Zhu
> <hongxing.zhu@nxp.com>
> Subject: [PATCH v1 1/5] PCI: imx6: Start link directly when workaround is not
> required
> 
> The current link setup procedure is more like one workaround to detect the
> device behind PCIe switches on some i.MX6 platforms.
> 
> To describe more accurately, change the flag name from
> IMX_PCIE_FLAG_IMX_SPEED_CHANGE to
> IMX_PCIE_FLAG_SPEED_CHANGE_WORKAROUND.
> 
> Then, start PCIe link directly when this flag is not set on i.MX7 or later
> paltforms to simple and speed up link training.
> 
> Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
> ---
>  drivers/pci/controller/dwc/pci-imx6.c | 34 +++++++++++----------------
>  1 file changed, 14 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> b/drivers/pci/controller/dwc/pci-imx6.c
> index c1f7904e3600..aa5c3f235995 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -91,7 +91,7 @@ enum imx_pcie_variants {  };
> 
>  #define IMX_PCIE_FLAG_IMX_PHY			BIT(0)
> -#define IMX_PCIE_FLAG_IMX_SPEED_CHANGE		BIT(1)
> +#define IMX_PCIE_FLAG_SPEED_CHANGE_WORDAROUND	BIT(1)
WORDAROUND/s/WORKAROUND
Sorry to find this typo error after patch-set is issued.
Would correct them all in next version.

Best Regards
Richard Zhu
>  #define IMX_PCIE_FLAG_SUPPORTS_SUSPEND		BIT(2)
>  #define IMX_PCIE_FLAG_HAS_PHYDRV		BIT(3)
>  #define IMX_PCIE_FLAG_HAS_APP_RESET		BIT(4)
> @@ -860,6 +860,12 @@ static int imx_pcie_start_link(struct dw_pcie *pci)
>  	u32 tmp;
>  	int ret;
> 
> +	if (!(imx_pcie->drvdata->flags &
> +	    IMX_PCIE_FLAG_SPEED_CHANGE_WORDAROUND)) {
> +		imx_pcie_ltssm_enable(dev);
> +		return 0;
> +	}
> +
>  	/*
>  	 * Force Gen1 operation when starting the link.  In case the link is
>  	 * started in Gen2 mode, there is a possibility the devices on the @@
> -896,22 +902,10 @@ static int imx_pcie_start_link(struct dw_pcie *pci)
>  		dw_pcie_writel_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL,
> tmp);
>  		dw_pcie_dbi_ro_wr_dis(pci);
> 
> -		if (imx_pcie->drvdata->flags &
> -		    IMX_PCIE_FLAG_IMX_SPEED_CHANGE) {
> -
> -			/*
> -			 * On i.MX7, DIRECT_SPEED_CHANGE behaves differently
> -			 * from i.MX6 family when no link speed transition
> -			 * occurs and we go Gen1 -> yep, Gen1. The difference
> -			 * is that, in such case, it will not be cleared by HW
> -			 * which will cause the following code to report false
> -			 * failure.
> -			 */
> -			ret = imx_pcie_wait_for_speed_change(imx_pcie);
> -			if (ret) {
> -				dev_err(dev, "Failed to bring link up!\n");
> -				goto err_reset_phy;
> -			}
> +		ret = imx_pcie_wait_for_speed_change(imx_pcie);
> +		if (ret) {
> +			dev_err(dev, "Failed to bring link up!\n");
> +			goto err_reset_phy;
>  		}
> 
>  		/* Make sure link training is finished as well! */ @@ -1665,7
> +1659,7 @@ static const struct imx_pcie_drvdata drvdata[] = {
>  	[IMX6Q] = {
>  		.variant = IMX6Q,
>  		.flags = IMX_PCIE_FLAG_IMX_PHY |
> -			 IMX_PCIE_FLAG_IMX_SPEED_CHANGE |
> +			 IMX_PCIE_FLAG_SPEED_CHANGE_WORDAROUND |
>  			 IMX_PCIE_FLAG_BROKEN_SUSPEND |
>  			 IMX_PCIE_FLAG_SUPPORTS_SUSPEND,
>  		.dbi_length = 0x200,
> @@ -1681,7 +1675,7 @@ static const struct imx_pcie_drvdata drvdata[] = {
>  	[IMX6SX] = {
>  		.variant = IMX6SX,
>  		.flags = IMX_PCIE_FLAG_IMX_PHY |
> -			 IMX_PCIE_FLAG_IMX_SPEED_CHANGE |
> +			 IMX_PCIE_FLAG_SPEED_CHANGE_WORDAROUND |
>  			 IMX_PCIE_FLAG_SUPPORTS_SUSPEND,
>  		.gpr = "fsl,imx6q-iomuxc-gpr",
>  		.ltssm_off = IOMUXC_GPR12,
> @@ -1696,7 +1690,7 @@ static const struct imx_pcie_drvdata drvdata[] = {
>  	[IMX6QP] = {
>  		.variant = IMX6QP,
>  		.flags = IMX_PCIE_FLAG_IMX_PHY |
> -			 IMX_PCIE_FLAG_IMX_SPEED_CHANGE |
> +			 IMX_PCIE_FLAG_SPEED_CHANGE_WORDAROUND |
>  			 IMX_PCIE_FLAG_SUPPORTS_SUSPEND,
>  		.dbi_length = 0x200,
>  		.gpr = "fsl,imx6q-iomuxc-gpr",
> --
> 2.37.1
Ilpo Järvinen March 24, 2025, 1:05 p.m. UTC | #2 
On Mon, 24 Mar 2025, Richard Zhu wrote:

> The current link setup procedure is more like one workaround to detect
> the device behind PCIe switches on some i.MX6 platforms.
> 
> To describe more accurately, change the flag name from
> IMX_PCIE_FLAG_IMX_SPEED_CHANGE to IMX_PCIE_FLAG_SPEED_CHANGE_WORKAROUND.
> 
> Then, start PCIe link directly when this flag is not set on i.MX7 or
> later paltforms to simple and speed up link training.
> 
> Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
> ---
>  drivers/pci/controller/dwc/pci-imx6.c | 34 +++++++++++----------------
>  1 file changed, 14 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index c1f7904e3600..aa5c3f235995 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -91,7 +91,7 @@ enum imx_pcie_variants {
>  };
>  
>  #define IMX_PCIE_FLAG_IMX_PHY			BIT(0)
> -#define IMX_PCIE_FLAG_IMX_SPEED_CHANGE		BIT(1)
> +#define IMX_PCIE_FLAG_SPEED_CHANGE_WORDAROUND	BIT(1)

WORDaround ?? :-)
diff mbox series

Patch

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index c1f7904e3600..aa5c3f235995 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -91,7 +91,7 @@  enum imx_pcie_variants {
 };
 
 #define IMX_PCIE_FLAG_IMX_PHY			BIT(0)
-#define IMX_PCIE_FLAG_IMX_SPEED_CHANGE		BIT(1)
+#define IMX_PCIE_FLAG_SPEED_CHANGE_WORDAROUND	BIT(1)
 #define IMX_PCIE_FLAG_SUPPORTS_SUSPEND		BIT(2)
 #define IMX_PCIE_FLAG_HAS_PHYDRV		BIT(3)
 #define IMX_PCIE_FLAG_HAS_APP_RESET		BIT(4)
@@ -860,6 +860,12 @@  static int imx_pcie_start_link(struct dw_pcie *pci)
 	u32 tmp;
 	int ret;
 
+	if (!(imx_pcie->drvdata->flags &
+	    IMX_PCIE_FLAG_SPEED_CHANGE_WORDAROUND)) {
+		imx_pcie_ltssm_enable(dev);
+		return 0;
+	}
+
 	/*
 	 * Force Gen1 operation when starting the link.  In case the link is
 	 * started in Gen2 mode, there is a possibility the devices on the
@@ -896,22 +902,10 @@  static int imx_pcie_start_link(struct dw_pcie *pci)
 		dw_pcie_writel_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL, tmp);
 		dw_pcie_dbi_ro_wr_dis(pci);
 
-		if (imx_pcie->drvdata->flags &
-		    IMX_PCIE_FLAG_IMX_SPEED_CHANGE) {
-
-			/*
-			 * On i.MX7, DIRECT_SPEED_CHANGE behaves differently
-			 * from i.MX6 family when no link speed transition
-			 * occurs and we go Gen1 -> yep, Gen1. The difference
-			 * is that, in such case, it will not be cleared by HW
-			 * which will cause the following code to report false
-			 * failure.
-			 */
-			ret = imx_pcie_wait_for_speed_change(imx_pcie);
-			if (ret) {
-				dev_err(dev, "Failed to bring link up!\n");
-				goto err_reset_phy;
-			}
+		ret = imx_pcie_wait_for_speed_change(imx_pcie);
+		if (ret) {
+			dev_err(dev, "Failed to bring link up!\n");
+			goto err_reset_phy;
 		}
 
 		/* Make sure link training is finished as well! */
@@ -1665,7 +1659,7 @@  static const struct imx_pcie_drvdata drvdata[] = {
 	[IMX6Q] = {
 		.variant = IMX6Q,
 		.flags = IMX_PCIE_FLAG_IMX_PHY |
-			 IMX_PCIE_FLAG_IMX_SPEED_CHANGE |
+			 IMX_PCIE_FLAG_SPEED_CHANGE_WORDAROUND |
 			 IMX_PCIE_FLAG_BROKEN_SUSPEND |
 			 IMX_PCIE_FLAG_SUPPORTS_SUSPEND,
 		.dbi_length = 0x200,
@@ -1681,7 +1675,7 @@  static const struct imx_pcie_drvdata drvdata[] = {
 	[IMX6SX] = {
 		.variant = IMX6SX,
 		.flags = IMX_PCIE_FLAG_IMX_PHY |
-			 IMX_PCIE_FLAG_IMX_SPEED_CHANGE |
+			 IMX_PCIE_FLAG_SPEED_CHANGE_WORDAROUND |
 			 IMX_PCIE_FLAG_SUPPORTS_SUSPEND,
 		.gpr = "fsl,imx6q-iomuxc-gpr",
 		.ltssm_off = IOMUXC_GPR12,
@@ -1696,7 +1690,7 @@  static const struct imx_pcie_drvdata drvdata[] = {
 	[IMX6QP] = {
 		.variant = IMX6QP,
 		.flags = IMX_PCIE_FLAG_IMX_PHY |
-			 IMX_PCIE_FLAG_IMX_SPEED_CHANGE |
+			 IMX_PCIE_FLAG_SPEED_CHANGE_WORDAROUND |
 			 IMX_PCIE_FLAG_SUPPORTS_SUSPEND,
 		.dbi_length = 0x200,
 		.gpr = "fsl,imx6q-iomuxc-gpr",