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drm/i915: Explain the magic numbers for AUX SYNC/precharge length

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[ Upstream commit 26bfc3f36f2104c174dfc72415547d5c28ef3f1c ]

Replace the hardcoded final numbers in the AUX SYNC/precharge
setup, and derive those from numbers from the (e)DP specs.

The new functions can serve as the single point of truth for
the number of SYNC pulses we use.

Cc: Jouni Högander <jouni.hogander@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230329172434.18744-2-ville.syrjala@linux.intel.com
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Stable-dep-of: 2d6f2f79e065 ("drm/i915: Use 18 fast wake AUX sync len")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Ville Syrjälä 2023-03-29 20:24:34 +03:00 committed by Greg Kroah-Hartman
parent 1d37434ffc
commit 7bf7bebdc2
1 changed files with 29 additions and 3 deletions
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32
drivers/gpu/drm/i915/display/intel_dp_aux.c
View File

@ -119,6 +119,32 @@ static u32 skl_get_aux_clock_divider(struct intel_dp *intel_dp, int index)
return index ? 0 : 1;
}
static int intel_dp_aux_sync_len(void)
{
int precharge = 16; /* 10-16 */
int preamble = 16;
return precharge + preamble;
}
static int intel_dp_aux_fw_sync_len(void)
{
int precharge = 16; /* 10-16 */
int preamble = 8;
return precharge + preamble;
}
static int g4x_dp_aux_precharge_len(void)
{
int precharge_min = 10;
int preamble = 16;
/* HW wants the length of the extra precharge in 2us units */
return (intel_dp_aux_sync_len() -
precharge_min - preamble) / 2;
}
static u32 g4x_get_aux_send_ctl(struct intel_dp *intel_dp,
int send_bytes,
u32 aux_clock_divider)
@ -141,7 +167,7 @@ static u32 g4x_get_aux_send_ctl(struct intel_dp *intel_dp,
timeout |
DP_AUX_CH_CTL_RECEIVE_ERROR |
(send_bytes << DP_AUX_CH_CTL_MESSAGE_SIZE_SHIFT) |
(3 << DP_AUX_CH_CTL_PRECHARGE_2US_SHIFT) |
(g4x_dp_aux_precharge_len() << DP_AUX_CH_CTL_PRECHARGE_2US_SHIFT) |
(aux_clock_divider << DP_AUX_CH_CTL_BIT_CLOCK_2X_SHIFT);
}
@ -165,8 +191,8 @@ static u32 skl_get_aux_send_ctl(struct intel_dp *intel_dp,
DP_AUX_CH_CTL_TIME_OUT_MAX |
DP_AUX_CH_CTL_RECEIVE_ERROR |
(send_bytes << DP_AUX_CH_CTL_MESSAGE_SIZE_SHIFT) |
DP_AUX_CH_CTL_FW_SYNC_PULSE_SKL(24) |
DP_AUX_CH_CTL_SYNC_PULSE_SKL(32);
DP_AUX_CH_CTL_FW_SYNC_PULSE_SKL(intel_dp_aux_fw_sync_len()) |
DP_AUX_CH_CTL_SYNC_PULSE_SKL(intel_dp_aux_sync_len());
if (intel_tc_port_in_tbt_alt_mode(dig_port))
ret |= DP_AUX_CH_CTL_TBT_IO;