[PATCH 21/24] drm/amd/display: Partition DPCD address space and break up transactions
Anson Jacob
Anson.Jacob at amd.com
Thu Jun 10 16:28:35 UTC 2021
From: Wesley Chalmers <Wesley.Chalmers at amd.com>
[WHY]
SCR for DP 2.0 spec says that multiple LTTPRs must not be accessed in a
single AUX transaction.
There may be other places in future where breaking up AUX accesses is
necessary.
[HOW]
Partition the entire DPCD address space into blocks. When an incoming AUX
request spans multiple blocks, break up the request into multiple requests.
Signed-off-by: Wesley Chalmers <Wesley.Chalmers at amd.com>
Reviewed-by: Jun Lei <Jun.Lei at amd.com>
Acked-by: Anson Jacob <Anson.Jacob at amd.com>
---
.../drm/amd/display/dc/core/dc_link_dpcd.c | 87 ++++++++++++++++++-
include/drm/drm_dp_helper.h | 17 ++++
2 files changed, 102 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dpcd.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_dpcd.c
index 8957565f87bc..27ec1e6e9c43 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dpcd.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dpcd.c
@@ -43,6 +43,60 @@ static enum dc_status internal_link_write_dpcd(
return DC_OK;
}
+/*
+ * Partition the entire DPCD address space
+ * XXX: This partitioning must cover the entire DPCD address space,
+ * and must contain no gaps or overlapping address ranges.
+ */
+static const struct dpcd_address_range mandatory_dpcd_partitions[] = {
+ { 0, DP_TRAINING_PATTERN_SET_PHY_REPEATER(DP_PHY_LTTPR1) - 1},
+ { DP_TRAINING_PATTERN_SET_PHY_REPEATER(DP_PHY_LTTPR1), DP_TRAINING_PATTERN_SET_PHY_REPEATER(DP_PHY_LTTPR2) - 1 },
+ { DP_TRAINING_PATTERN_SET_PHY_REPEATER(DP_PHY_LTTPR2), DP_TRAINING_PATTERN_SET_PHY_REPEATER(DP_PHY_LTTPR3) - 1 },
+ { DP_TRAINING_PATTERN_SET_PHY_REPEATER(DP_PHY_LTTPR3), DP_TRAINING_PATTERN_SET_PHY_REPEATER(DP_PHY_LTTPR4) - 1 },
+ { DP_TRAINING_PATTERN_SET_PHY_REPEATER(DP_PHY_LTTPR4), DP_TRAINING_PATTERN_SET_PHY_REPEATER(DP_PHY_LTTPR5) - 1 },
+ { DP_TRAINING_PATTERN_SET_PHY_REPEATER(DP_PHY_LTTPR5), DP_TRAINING_PATTERN_SET_PHY_REPEATER(DP_PHY_LTTPR6) - 1 },
+ { DP_TRAINING_PATTERN_SET_PHY_REPEATER(DP_PHY_LTTPR6), DP_TRAINING_PATTERN_SET_PHY_REPEATER(DP_PHY_LTTPR7) - 1 },
+ { DP_TRAINING_PATTERN_SET_PHY_REPEATER(DP_PHY_LTTPR7), DP_TRAINING_PATTERN_SET_PHY_REPEATER(DP_PHY_LTTPR8) - 1 },
+ { DP_TRAINING_PATTERN_SET_PHY_REPEATER(DP_PHY_LTTPR8), DP_FEC_STATUS_PHY_REPEATER(DP_PHY_LTTPR1) - 1 },
+ /*
+ * The FEC registers are contiguous
+ */
+ { DP_FEC_STATUS_PHY_REPEATER(DP_PHY_LTTPR1), DP_FEC_STATUS_PHY_REPEATER(DP_PHY_LTTPR1) - 1 },
+ { DP_FEC_STATUS_PHY_REPEATER(DP_PHY_LTTPR2), DP_FEC_STATUS_PHY_REPEATER(DP_PHY_LTTPR2) - 1 },
+ { DP_FEC_STATUS_PHY_REPEATER(DP_PHY_LTTPR3), DP_FEC_STATUS_PHY_REPEATER(DP_PHY_LTTPR3) - 1 },
+ { DP_FEC_STATUS_PHY_REPEATER(DP_PHY_LTTPR4), DP_FEC_STATUS_PHY_REPEATER(DP_PHY_LTTPR4) - 1 },
+ { DP_FEC_STATUS_PHY_REPEATER(DP_PHY_LTTPR5), DP_FEC_STATUS_PHY_REPEATER(DP_PHY_LTTPR5) - 1 },
+ { DP_FEC_STATUS_PHY_REPEATER(DP_PHY_LTTPR6), DP_FEC_STATUS_PHY_REPEATER(DP_PHY_LTTPR6) - 1 },
+ { DP_FEC_STATUS_PHY_REPEATER(DP_PHY_LTTPR7), DP_FEC_STATUS_PHY_REPEATER(DP_PHY_LTTPR7) - 1 },
+ { DP_FEC_STATUS_PHY_REPEATER(DP_PHY_LTTPR8), DP_LTTPR_MAX_ADD },
+ /* all remaining DPCD addresses */
+ { DP_LTTPR_MAX_ADD + 1, DP_DPCD_MAX_ADD } };
+
+static inline bool do_addresses_intersect_with_range(
+ const struct dpcd_address_range *range,
+ const uint32_t start_address,
+ const uint32_t end_address)
+{
+ return start_address <= range->end && end_address >= range->start;
+}
+
+static uint32_t dpcd_get_next_partition_size(const uint32_t address, const uint32_t size)
+{
+ const uint32_t end_address = END_ADDRESS(address, size);
+ uint32_t partition_iterator = 0;
+
+ /*
+ * find current partition
+ * this loop spins forever if partition map above is not surjective
+ */
+ while (!do_addresses_intersect_with_range(&mandatory_dpcd_partitions[partition_iterator],
+ address, end_address))
+ partition_iterator++;
+ if (end_address < mandatory_dpcd_partitions[partition_iterator].end)
+ return size;
+ return ADDRESS_RANGE_SIZE(address, mandatory_dpcd_partitions[partition_iterator].end);
+}
+
/*
* Ranges of DPCD addresses that must be read in a single transaction
* XXX: Do not allow any two address ranges in this array to overlap
@@ -115,12 +169,28 @@ enum dc_status core_link_read_dpcd(
uint32_t size)
{
uint32_t extended_address;
+ uint32_t partitioned_address;
uint8_t *extended_data;
uint32_t extended_size;
+ /* size of the remaining partitioned address space */
+ uint32_t size_left_to_read;
enum dc_status status;
+ /* size of the next partition to be read from */
+ uint32_t partition_size;
+ uint32_t data_index = 0;
dpcd_extend_address_range(address, data, size, &extended_address, &extended_data, &extended_size);
- status = internal_link_read_dpcd(link, extended_address, extended_data, extended_size);
+ partitioned_address = extended_address;
+ size_left_to_read = extended_size;
+ while (size_left_to_read) {
+ partition_size = dpcd_get_next_partition_size(partitioned_address, size_left_to_read);
+ status = internal_link_read_dpcd(link, partitioned_address, &extended_data[data_index], partition_size);
+ if (status != DC_OK)
+ break;
+ partitioned_address += partition_size;
+ data_index += partition_size;
+ size_left_to_read -= partition_size;
+ }
dpcd_reduce_address_range(extended_address, extended_data, extended_size, address, data, size);
return status;
}
@@ -131,5 +201,18 @@ enum dc_status core_link_write_dpcd(
const uint8_t *data,
uint32_t size)
{
- return internal_link_write_dpcd(link, address, data, size);
+ uint32_t partition_size;
+ uint32_t data_index = 0;
+ enum dc_status status;
+
+ while (size) {
+ partition_size = dpcd_get_next_partition_size(address, size);
+ status = internal_link_write_dpcd(link, address, &data[data_index], partition_size);
+ if (status != DC_OK)
+ break;
+ address += partition_size;
+ data_index += partition_size;
+ size -= partition_size;
+ }
+ return status;
}
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index edffd1dcca3e..35ac1f537530 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1369,10 +1369,27 @@ enum drm_dp_phy {
#define DP_SYMBOL_ERROR_COUNT_LANE1_PHY_REPEATER1 0xf0037 /* 1.3 */
#define DP_SYMBOL_ERROR_COUNT_LANE2_PHY_REPEATER1 0xf0039 /* 1.3 */
#define DP_SYMBOL_ERROR_COUNT_LANE3_PHY_REPEATER1 0xf003b /* 1.3 */
+
+#define __DP_FEC1_BASE 0xf0290 /* 1.4 */
+#define __DP_FEC2_BASE 0xf0298 /* 1.4 */
+#define DP_FEC_BASE(dp_phy) \
+ (__DP_FEC1_BASE + ((__DP_FEC2_BASE - __DP_FEC1_BASE) * \
+ ((dp_phy) - DP_PHY_LTTPR1)))
+
+#define DP_FEC_REG(dp_phy, fec1_reg) \
+ (DP_FEC_BASE(dp_phy) - DP_FEC_BASE(DP_PHY_LTTPR1) + fec1_reg)
+
#define DP_FEC_STATUS_PHY_REPEATER1 0xf0290 /* 1.4 */
+#define DP_FEC_STATUS_PHY_REPEATER(dp_phy) \
+ DP_FEC_REG(dp_phy, DP_FEC_STATUS_PHY_REPEATER1)
+
#define DP_FEC_ERROR_COUNT_PHY_REPEATER1 0xf0291 /* 1.4 */
#define DP_FEC_CAPABILITY_PHY_REPEATER1 0xf0294 /* 1.4a */
+#define DP_LTTPR_MAX_ADD 0xf02ff /* 1.4 */
+
+#define DP_DPCD_MAX_ADD 0xfffff /* 1.4 */
+
/* Repeater modes */
#define DP_PHY_REPEATER_MODE_TRANSPARENT 0x55 /* 1.3 */
#define DP_PHY_REPEATER_MODE_NON_TRANSPARENT 0xaa /* 1.3 */
--
2.25.1
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