From: Thierry Reding <thierry.reding@gmail.com>
To: dri-devel@lists.freedesktop.org
Subject: [PATCH v2 13/21] drm/dp: Do not busy-loop during link training
Date: Mon, 2 Sep 2019 13:31:13 +0200 [thread overview]
Message-ID: <20190902113121.31323-14-thierry.reding@gmail.com> (raw)
In-Reply-To: <20190902113121.31323-1-thierry.reding@gmail.com>
From: Thierry Reding <treding@nvidia.com>
Use microsecond sleeps for the clock recovery and channel equalization
delays during link training. The duration of these delays can be from
100 us up to 16 ms. It is rude to busy-loop for that amount of time.
While at it, also convert to standard coding style by putting the
opening braces in a function definition on a new line.
v2: use correct multiplier for training delays (Philipp Zabel)
Signed-off-by: Thierry Reding <treding@nvidia.com>
---
drivers/gpu/drm/drm_dp_helper.c | 30 ++++++++++++++++++------------
1 file changed, 18 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 4112570dbe67..681d28988776 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -120,33 +120,39 @@ u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SI
}
EXPORT_SYMBOL(drm_dp_get_adjust_request_pre_emphasis);
-void drm_dp_link_train_clock_recovery_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) {
- int rd_interval = dpcd[DP_TRAINING_AUX_RD_INTERVAL] &
- DP_TRAINING_AUX_RD_MASK;
+void drm_dp_link_train_clock_recovery_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+ unsigned int rd_interval = dpcd[DP_TRAINING_AUX_RD_INTERVAL] &
+ DP_TRAINING_AUX_RD_MASK;
if (rd_interval > 4)
- DRM_DEBUG_KMS("AUX interval %d, out of range (max 4)\n",
+ DRM_DEBUG_KMS("AUX interval %u, out of range (max 4)\n",
rd_interval);
if (rd_interval == 0 || dpcd[DP_DPCD_REV] >= DP_DPCD_REV_14)
- udelay(100);
+ rd_interval = 100;
else
- mdelay(rd_interval * 4);
+ rd_interval *= 4 * USEC_PER_MSEC;
+
+ usleep_range(rd_interval, rd_interval * 2);
}
EXPORT_SYMBOL(drm_dp_link_train_clock_recovery_delay);
-void drm_dp_link_train_channel_eq_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) {
- int rd_interval = dpcd[DP_TRAINING_AUX_RD_INTERVAL] &
- DP_TRAINING_AUX_RD_MASK;
+void drm_dp_link_train_channel_eq_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+ unsigned int rd_interval = dpcd[DP_TRAINING_AUX_RD_INTERVAL] &
+ DP_TRAINING_AUX_RD_MASK;
if (rd_interval > 4)
- DRM_DEBUG_KMS("AUX interval %d, out of range (max 4)\n",
+ DRM_DEBUG_KMS("AUX interval %u, out of range (max 4)\n",
rd_interval);
if (rd_interval == 0)
- udelay(400);
+ rd_interval = 400;
else
- mdelay(rd_interval * 4);
+ rd_interval *= 4 * USEC_PER_MSEC;
+
+ usleep_range(rd_interval, rd_interval * 2);
}
EXPORT_SYMBOL(drm_dp_link_train_channel_eq_delay);
--
2.22.0
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next prev parent reply other threads:[~2019-09-02 11:31 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-02 11:31 [PATCH v2 00/21] drm/dp: Various helper improvements and cleanups Thierry Reding
2019-09-02 11:31 ` [PATCH v2 01/21] drm/dp: Sort includes alphabetically Thierry Reding
2019-09-02 11:31 ` [PATCH v2 02/21] drm/dp: Add missing kerneldoc for struct drm_dp_link Thierry Reding
2019-09-02 11:31 ` [PATCH v2 03/21] drm/dp: Add drm_dp_link_reset() implementation Thierry Reding
2019-09-02 11:31 ` [PATCH v2 04/21] drm/dp: Track link capabilities alongside settings Thierry Reding
2019-09-02 11:31 ` [PATCH v2 05/21] drm/dp: Turn link capabilities into booleans Thierry Reding
2019-09-02 11:31 ` [PATCH v2 06/21] drm/dp: Probe link using existing parsing helpers Thierry Reding
2019-09-02 11:31 ` [PATCH v2 07/21] drm/dp: Read fast training capability from link Thierry Reding
2019-09-02 11:31 ` [PATCH v2 08/21] drm/dp: Read TPS3 capability from sink Thierry Reding
2019-09-02 11:31 ` [PATCH v2 09/21] drm/dp: Read channel coding " Thierry Reding
2019-09-02 11:31 ` [PATCH v2 10/21] drm/dp: Read alternate scrambler reset " Thierry Reding
2019-09-02 11:31 ` [PATCH v2 11/21] drm/dp: Read eDP version from DPCD Thierry Reding
2019-09-02 11:31 ` [PATCH v2 12/21] drm/dp: Read AUX read interval " Thierry Reding
2019-09-02 11:31 ` Thierry Reding [this message]
2019-09-02 11:31 ` [PATCH v2 14/21] drm/dp: Use drm_dp_aux_rd_interval() Thierry Reding
2019-09-02 11:31 ` [PATCH v2 15/21] drm/dp: Add helper to get post-cursor adjustments Thierry Reding
2019-09-02 11:31 ` [PATCH v2 16/21] drm/dp: Set channel coding on link configuration Thierry Reding
2019-09-02 11:31 ` [PATCH v2 17/21] drm/dp: Enable alternate scrambler reset when supported Thierry Reding
2019-09-02 11:31 ` [PATCH v2 18/21] drm/dp: Add drm_dp_link_choose() helper Thierry Reding
2019-09-02 11:31 ` [PATCH v2 19/21] drm/dp: Add support for eDP link rates Thierry Reding
2019-09-02 11:31 ` [PATCH v2 20/21] drm/dp: Remove a gratuituous blank line Thierry Reding
2019-09-02 11:31 ` [PATCH v2 21/21] drm/bridge: tc358767: Use DP nomenclature Thierry Reding
2019-09-20 16:00 ` [PATCH v2 00/21] drm/dp: Various helper improvements and cleanups Thierry Reding
2019-09-23 13:52 ` Jani Nikula
2019-09-23 14:52 ` Thierry Reding
2019-10-02 16:14 ` Thierry Reding
2019-10-08 9:42 ` Daniel Vetter
2019-10-08 23:05 ` Lyude Paul
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