[PATCH v2 1/1] usb: typec: ucsi_ccg: Disable UCSI ALT support on Tegra

[Wayne Chang <waynec@nvidia.com>]

From: Sing-Han Chen <singhanc@nvidia.com>

Firmware built for Tegra doesn't support UCSI ALT command and has known
issue of reporting wrong capability info.

This commit disables UCSI ALT support when reading the capability on
Tegra.

Signed-off-by: Sing-Han Chen <singhanc@nvidia.com>
Signed-off-by: Wayne Chang <waynec@nvidia.com>
---
V1 -> V2: updated the commit message and removed the unnecessary changes for RTX
We are now enabling the NVIDIA Tegra products on upstream kernel.
The change is to add the Cypress cypd 4226 support for NVIDA Tegra
products including Xavier AGX, Xavier Orin and the upcoming products.
The Cypress cypd4226 is not enabled in current kernel codebase.
And thus, we shall not need it for stable kernels and backporting

 drivers/usb/typec/ucsi/ucsi_ccg.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/usb/typec/ucsi/ucsi_ccg.c b/drivers/usb/typec/ucsi/ucsi_ccg.c
index 5c0bf48be766..cbd93f893e48 100644
--- a/drivers/usb/typec/ucsi/ucsi_ccg.c
+++ b/drivers/usb/typec/ucsi/ucsi_ccg.c
@@ -125,6 +125,11 @@ struct version_format {
 #define CCG_FW_BUILD_NVIDIA	(('n' << 8) | 'v')
 #define CCG_OLD_FW_VERSION	(CCG_VERSION(0x31) | CCG_VERSION_PATCH(10))
 
+/* Firmware for Tegra doesn't support UCSI ALT command, built
+ * for NVIDIA has known issue of reporting wrong capability info
+ */
+#define CCG_FW_BUILD_NVIDIA_TEGRA	(('g' << 8) | 'n')
+
 /* Altmode offset for NVIDIA Function Test Board (FTB) */
 #define NVIDIA_FTB_DP_OFFSET	(2)
 #define NVIDIA_FTB_DBG_OFFSET	(3)
@@ -513,6 +518,7 @@ static int ucsi_ccg_read(struct ucsi *ucsi, unsigned int offset,
 {
 	struct ucsi_ccg *uc = ucsi_get_drvdata(ucsi);
 	u16 reg = CCGX_RAB_UCSI_DATA_BLOCK(offset);
+	struct ucsi_capability *cap;
 	struct ucsi_altmode *alt;
 	int ret;
 
@@ -536,6 +542,12 @@ static int ucsi_ccg_read(struct ucsi *ucsi, unsigned int offset,
 				ucsi_ccg_nvidia_altmode(uc, alt);
 		}
 		break;
+	case UCSI_GET_CAPABILITY:
+		if (uc->fw_build == CCG_FW_BUILD_NVIDIA_TEGRA) {
+			cap = val;
+			cap->features &= ~UCSI_CAP_ALT_MODE_DETAILS;
+		}
+		break;
 	default:
 		break;
 	}
-- 
2.25.1