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, 2 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_log.c b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_log.c
index 6b3b5f610907..ac44ee1532fd 100644
--- a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_log.c
+++ b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_log.c
@@ -248,6 +248,8 @@ char *mod_hdcp_status_to_str(int32_t status)
 		return "MOD_HDCP_STATUS_HDCP2_DEVICE_COUNT_MISMATCH_FAILURE";
 	case MOD_HDCP_STATUS_UNSUPPORTED_PSP_VER_FAILURE:
 		return "MOD_HDCP_STATUS_UNSUPPORTED_PSP_VER_FAILURE";
+	case MOD_HDCP_STATUS_HDCP2_LOCALITY_COMBO_READ_FAILURE:
+		return "MOD_HDCP_STATUS_HDCP2_LOCALITY_COMBO_READ_FAILURE";
 	default:
 		return "MOD_HDCP_STATUS_UNKNOWN";
 	}