PCI: qcom: Add equalization settings for 16.0 GT/s

During high data transmission rates such as 16.0 GT/s, there is an
increased risk of signal loss due to poor channel quality and
interference. This can impact receiver's ability to capture signals
accurately.

Hence, as signal compensation is achieved through appropriate lane
equalization, apply lane equalization settings at both transmitter
and receiver which results in an increase in the PCIe signal strength.

While at it, modify the pcie-tegra194 driver to make use of the
common GEN3_EQ_CONTROL_OFF definitions in pcie-designware.h.

Link: https://lore.kernel.org/linux-pci/[email protected]
Tested-by: Johan Hovold <[email protected]>
Signed-off-by: Shashank Babu Chinta Venkata <[email protected]>
[mani: dropped the code refactoring and minor changes]
Signed-off-by: Manivannan Sadhasivam <[email protected]>
[kwilczynski: commit log]
Signed-off-by: Krzysztof Wilczyński <[email protected]>
Reviewed-by: Johan Hovold <[email protected]>
Reviewed-by: Manivannan Sadhasivam <[email protected]>

1 files changed, 7 insertions, 12 deletions

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index 4bf7b433417a..6e03e14151d6 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -177,11 +177,6 @@
 #define N_FTS_VAL					52
 #define FTS_VAL						52
 
-#define GEN3_EQ_CONTROL_OFF			0x8a8
-#define GEN3_EQ_CONTROL_OFF_PSET_REQ_VEC_SHIFT	8
-#define GEN3_EQ_CONTROL_OFF_PSET_REQ_VEC_MASK	GENMASK(23, 8)
-#define GEN3_EQ_CONTROL_OFF_FB_MODE_MASK	GENMASK(3, 0)
-
 #define PORT_LOGIC_AMBA_ERROR_RESPONSE_DEFAULT	0x8D0
 #define AMBA_ERROR_RESPONSE_CRS_SHIFT		3
 #define AMBA_ERROR_RESPONSE_CRS_MASK		GENMASK(1, 0)
@@ -861,9 +856,9 @@ static void config_gen3_gen4_eq_presets(struct tegra_pcie_dw *pcie)
 	dw_pcie_writel_dbi(pci, GEN3_RELATED_OFF, val);
 
 	val = dw_pcie_readl_dbi(pci, GEN3_EQ_CONTROL_OFF);
-	val &= ~GEN3_EQ_CONTROL_OFF_PSET_REQ_VEC_MASK;
-	val |= (0x3ff << GEN3_EQ_CONTROL_OFF_PSET_REQ_VEC_SHIFT);
-	val &= ~GEN3_EQ_CONTROL_OFF_FB_MODE_MASK;
+	val &= ~GEN3_EQ_CONTROL_OFF_PSET_REQ_VEC;
+	val |= FIELD_PREP(GEN3_EQ_CONTROL_OFF_PSET_REQ_VEC, 0x3ff);
+	val &= ~GEN3_EQ_CONTROL_OFF_FB_MODE;
 	dw_pcie_writel_dbi(pci, GEN3_EQ_CONTROL_OFF, val);
 
 	val = dw_pcie_readl_dbi(pci, GEN3_RELATED_OFF);
@@ -872,10 +867,10 @@ static void config_gen3_gen4_eq_presets(struct tegra_pcie_dw *pcie)
 	dw_pcie_writel_dbi(pci, GEN3_RELATED_OFF, val);
 
 	val = dw_pcie_readl_dbi(pci, GEN3_EQ_CONTROL_OFF);
-	val &= ~GEN3_EQ_CONTROL_OFF_PSET_REQ_VEC_MASK;
-	val |= (pcie->of_data->gen4_preset_vec <<
-		GEN3_EQ_CONTROL_OFF_PSET_REQ_VEC_SHIFT);
-	val &= ~GEN3_EQ_CONTROL_OFF_FB_MODE_MASK;
+	val &= ~GEN3_EQ_CONTROL_OFF_PSET_REQ_VEC;
+	val |= FIELD_PREP(GEN3_EQ_CONTROL_OFF_PSET_REQ_VEC,
+			  pcie->of_data->gen4_preset_vec);
+	val &= ~GEN3_EQ_CONTROL_OFF_FB_MODE;
 	dw_pcie_writel_dbi(pci, GEN3_EQ_CONTROL_OFF, val);
 
 	val = dw_pcie_readl_dbi(pci, GEN3_RELATED_OFF);