drm/amd/display: fw locality check refactors

[why]
There are some new changes for HDCP2 firmware locality check. The
implementation doesn't perfectly fit the intended design and clarity.

1. Clarify and consolidate variable responsibilities.
The previous implementation introduced the following variables:
- config.ddc.funcs.atomic_write_poll_read_i2c (optional pointer)
- hdcp->config.ddc.funcs.atomic_write_poll_read_aux (optional pointer)
- hdcp->connection.link.adjust.hdcp2.force_sw_locality_check (bool)
- hdcp->config.debug.lc_enable_sw_fallback (bool)
- use_fw (bool)
They will be used together to determine two operations:
- Whether to use FW locality check
- Whether to use SW fallback on FW locality check failure
The refactor streamlines this by introducing two variables in the hdcp2
link adjustment, while ensuring function pointers are always assigned
and remain independent from policy decisions:
- use_fw_locality_check (bool) -> true if fw locality should be used.
- use_sw_locality_fallback (bool) -> true to reset use_fw_locality_check
back to false and retry on fw locality check failure.

2. Mixed meanings of l_prime_read transition input
l_prime_read originally means if l_prime is read when sw locality check
is used. When FW locality check is used, l_prime_read means if lc init
write, l prime poll and l_prime read combo operation is successful. The
mix of meanings is confusing. The refactor introduces a new variable
l_prime_combo_read to isolate the second meaning into its own variable.

3. Missing specific error code on firmware locality error.
The original change reuses the generic DDC failure error code when
firmware fails to return locality check result. This is not ideal as
DDC failure indicates an error occurred during an I2C/AUX transaction.
FW locality failure could be caused by polling timeout in firmware or
failure to acquire firmware access. Which sits at a higher level of
abstraction above DDC hardware. An incorrect error code could mislead
the debug into a wrong direction.

4. Correcting misplaced comments. The previous implementation of the
firmware locality check resulted in some comments in hdcp2_transition
being incorrectly positioned. This refactor relocates those comments to
their appropriate locations for better clarity.

Reviewed-by: Aric Cyr <aric.cyr@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 4 insertions, 6 deletions

diff --git a/drivers/gpu/drm/amd/display/modules/inc/mod_hdcp.h b/drivers/gpu/drm/amd/display/modules/inc/mod_hdcp.h
index 46e52fb3a118..264348989e9b 100644
--- a/drivers/gpu/drm/amd/display/modules/inc/mod_hdcp.h
+++ b/drivers/gpu/drm/amd/display/modules/inc/mod_hdcp.h
@@ -98,6 +98,7 @@ enum mod_hdcp_status {
 	MOD_HDCP_STATUS_HDCP2_REAUTH_LINK_INTEGRITY_FAILURE,
 	MOD_HDCP_STATUS_HDCP2_DEVICE_COUNT_MISMATCH_FAILURE,
 	MOD_HDCP_STATUS_UNSUPPORTED_PSP_VER_FAILURE,
+	MOD_HDCP_STATUS_HDCP2_LOCALITY_COMBO_READ_FAILURE,
 };
 
 struct mod_hdcp_displayport {
@@ -214,8 +215,9 @@ struct mod_hdcp_link_adjustment_hdcp2 {
 	uint8_t force_type		: 2;
 	uint8_t force_no_stored_km	: 1;
 	uint8_t increase_h_prime_timeout: 1;
-	uint8_t force_sw_locality_check : 1;
-	uint8_t reserved		: 2;
+	uint8_t use_fw_locality_check 	: 1;
+	uint8_t use_sw_locality_fallback: 1;
+	uint8_t reserved		: 1;
 };
 
 struct mod_hdcp_link_adjustment {
@@ -317,10 +319,6 @@ struct mod_hdcp_display_query {
 struct mod_hdcp_config {
 	struct mod_hdcp_psp psp;
 	struct mod_hdcp_ddc ddc;
-	struct {
-		uint8_t lc_enable_sw_fallback : 1;
-		uint8_t reserved : 7;
-	} debug;
 	uint8_t index;
 };