Introduces support for programming the 18-bit TX Deemphasis value that
drives the pipe_TxDeemph signal, as defined in the PIPE4 specification.

The configured value is recommended by Synopsys and is intended for
standard (non-compliance) operation. These Gen2 equalization settings
have been validated through both internal and external compliance
testing. By applying this setting, the stability of USB 3.2 enumeration
is improved and now SuperSpeedPlus devices are consistently recognized as
USB 3.2 Gen 2 by the MMI USB Host controller.

Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
---
 drivers/usb/dwc3/core.c        | 17 +++++++++++++++++
 drivers/usb/dwc3/core.h        |  7 +++++++
 drivers/usb/dwc3/dwc3-xilinx.c |  7 ++++++-
 3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 7b84512b13a2..cb737aee316e 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -647,6 +647,15 @@ static void dwc3_config_soc_bus(struct dwc3 *dwc)
 		reg |= DWC3_GSBUSCFG0_REQINFO(dwc->gsbuscfg0_reqinfo);
 		dwc3_writel(dwc->regs, DWC3_GSBUSCFG0, reg);
 	}
+
+	if (dwc->csr_tx_deemph_field_1 != DWC3_LCSR_TX_DEEMPH_UNSPECIFIED) {
+		u32 reg;
+
+		reg = dwc3_readl(dwc->regs, DWC3_LCSR_TX_DEEMPH);
+		reg &= ~DWC3_LCSR_TX_DEEMPH_MASK(~0);
+		reg |= DWC3_LCSR_TX_DEEMPH_MASK(dwc->csr_tx_deemph_field_1);
+		dwc3_writel(dwc->regs, DWC3_LCSR_TX_DEEMPH, reg);
+	}
 }
 
 static int dwc3_core_ulpi_init(struct dwc3 *dwc)
@@ -1674,11 +1683,13 @@ static void dwc3_core_exit_mode(struct dwc3 *dwc)
 static void dwc3_get_software_properties(struct dwc3 *dwc,
 					 const struct dwc3_properties *properties)
 {
+	u32 csr_tx_deemph_field_1;
 	struct device *tmpdev;
 	u16 gsbuscfg0_reqinfo;
 	int ret;
 
 	dwc->gsbuscfg0_reqinfo = DWC3_GSBUSCFG0_REQINFO_UNSPECIFIED;
+	dwc->csr_tx_deemph_field_1 = DWC3_LCSR_TX_DEEMPH_UNSPECIFIED;
 
 	if (properties->gsbuscfg0_reqinfo !=
 	    DWC3_GSBUSCFG0_REQINFO_UNSPECIFIED) {
@@ -1696,6 +1707,12 @@ static void dwc3_get_software_properties(struct dwc3 *dwc,
 					       &gsbuscfg0_reqinfo);
 		if (!ret)
 			dwc->gsbuscfg0_reqinfo = gsbuscfg0_reqinfo;
+
+		ret = device_property_read_u32(tmpdev,
+					       "snps,lcsr_tx_deemph",
+					       &csr_tx_deemph_field_1);
+		if (!ret)
+			dwc->csr_tx_deemph_field_1 = csr_tx_deemph_field_1;
 	}
 }
 
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index a5fc92c4ffa3..32205f435b5b 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -181,6 +181,7 @@
 
 #define DWC3_LLUCTL(n)		(0xd024 + ((n) * 0x80))
 
+#define DWC3_LCSR_TX_DEEMPH	0xd060
 /* Bit fields */
 
 /* Global SoC Bus Configuration INCRx Register 0 */
@@ -198,6 +199,10 @@
 #define DWC3_GSBUSCFG0_REQINFO(n)	(((n) & 0xffff) << 16)
 #define DWC3_GSBUSCFG0_REQINFO_UNSPECIFIED	0xffffffff
 
+/* LCSR_TX_DEEMPH Register:  setting TX deemphasis used in normal operation in gen2 */
+#define DWC3_LCSR_TX_DEEMPH_MASK(n)		((n) & 0x3ffff)
+#define DWC3_LCSR_TX_DEEMPH_UNSPECIFIED		0xffffffff
+
 /* Global Debug LSP MUX Select */
 #define DWC3_GDBGLSPMUX_ENDBC		BIT(15)	/* Host only */
 #define DWC3_GDBGLSPMUX_HOSTSELECT(n)	((n) & 0x3fff)
@@ -1180,6 +1185,7 @@ struct dwc3_glue_ops {
  * @wakeup_pending_funcs: Indicates whether any interface has requested for
  *			 function wakeup in bitmap format where bit position
  *			 represents interface_id.
+ * @csr_tx_deemph_field_1: stores TX deemphasis used in Gen2 operation.
  */
 struct dwc3 {
 	struct work_struct	drd_work;
@@ -1414,6 +1420,7 @@ struct dwc3 {
 	struct dentry		*debug_root;
 	u32			gsbuscfg0_reqinfo;
 	u32			wakeup_pending_funcs;
+	u32			csr_tx_deemph_field_1;
 };
 
 #define INCRX_BURST_MODE 0
diff --git a/drivers/usb/dwc3/dwc3-xilinx.c b/drivers/usb/dwc3/dwc3-xilinx.c
index 32f87a238d0e..85bc4ab461fd 100644
--- a/drivers/usb/dwc3/dwc3-xilinx.c
+++ b/drivers/usb/dwc3/dwc3-xilinx.c
@@ -40,6 +40,7 @@
 #define PIPE_CLK_SELECT				0
 #define XLNX_USB_FPD_POWER_PRSNT		0x80
 #define FPD_POWER_PRSNT_OPTION			BIT(0)
+#define XLNX_MMI_USB_TX_DEEMPH_DEF		0x8c45
 
 struct dwc3_xlnx {
 	int				num_clocks;
@@ -306,7 +307,7 @@ MODULE_DEVICE_TABLE(of, dwc3_xlnx_of_match);
 static int dwc3_set_swnode(struct device *dev)
 {
 	struct device_node *np = dev->of_node, *dwc3_np;
-	struct property_entry props[2];
+	struct property_entry props[3];
 	int prop_idx = 0, ret = 0;
 
 	dwc3_np = of_get_compatible_child(np, "snps,dwc3");
@@ -320,6 +321,10 @@ static int dwc3_set_swnode(struct device *dev)
 	if (of_dma_is_coherent(dwc3_np))
 		props[prop_idx++] = PROPERTY_ENTRY_U16("snps,gsbuscfg0-reqinfo",
 						       0xffff);
+	if (of_device_is_compatible(np, "xlnx,versal2-mmi-dwc3"))
+		props[prop_idx++] = PROPERTY_ENTRY_U32("snps,lcsr_tx_deemph",
+						       XLNX_MMI_USB_TX_DEEMPH_DEF);
+
 	of_node_put(dwc3_np);
 
 	if (prop_idx)
-- 
2.34.1

On Thu, Nov 20, 2025 at 01:00:36AM +0530, Radhey Shyam Pandey wrote:
>  struct dwc3_xlnx {
>  	int				num_clocks;
> @@ -306,7 +307,7 @@ MODULE_DEVICE_TABLE(of, dwc3_xlnx_of_match);
>  static int dwc3_set_swnode(struct device *dev)
>  {
>  	struct device_node *np = dev->of_node, *dwc3_np;
> -	struct property_entry props[2];
> +	struct property_entry props[3];
>  	int prop_idx = 0, ret = 0;
>  
>  	dwc3_np = of_get_compatible_child(np, "snps,dwc3");
> @@ -320,6 +321,10 @@ static int dwc3_set_swnode(struct device *dev)
>  	if (of_dma_is_coherent(dwc3_np))
>  		props[prop_idx++] = PROPERTY_ENTRY_U16("snps,gsbuscfg0-reqinfo",
>  						       0xffff);
> +	if (of_device_is_compatible(np, "xlnx,versal2-mmi-dwc3"))

Don't sprinkle compatibles all over the code - it does not scale. You
have driver match data for that.

Best regards,
Krzysztof