Received-SPF: pass (google.com: domain of linux-kernel+bounces-155660-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1;
From: Sean Anderson <sean.anderson@linux.dev>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	dri-devel@lists.freedesktop.org
Cc: Daniel Vetter <daniel@ffwll.ch>,
	linux-arm-kernel@lists.infradead.org,
	Michal Simek <michal.simek@amd.com>,
	linux-kernel@vger.kernel.org,
	David Airlie <airlied@gmail.com>,
	Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>,
	Sean Anderson <sean.anderson@linux.dev>
Subject: [PATCH v4 11/13] drm: zynqmp_dp: Split off several helper functions
Date: Tue, 23 Apr 2024 13:18:57 -0400
Message-Id: <20240423171859.3953024-12-sean.anderson@linux.dev>
In-Reply-To: <20240423171859.3953024-1-sean.anderson@linux.dev>
References: <20240423171859.3953024-1-sean.anderson@linux.dev>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

In preparation for supporting compliance testing, split off several
helper functions. No functional change intended.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---

(no changes since v1)

 drivers/gpu/drm/xlnx/zynqmp_dp.c | 49 ++++++++++++++++++++++----------
 1 file changed, 34 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
index 863668642190..d5ee165046f8 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
@@ -635,6 +635,7 @@ static void zynqmp_dp_adjust_train(struct zynqmp_dp *dp,
 /**
  * zynqmp_dp_update_vs_emph - Update the training values
  * @dp: DisplayPort IP core structure
+ * @train_set: A set of training values
  *
  * Update the training values based on the request from sink. The mapped values
  * are predefined, and values(vs, pe, pc) are from the device manual.
@@ -642,12 +643,12 @@ static void zynqmp_dp_adjust_train(struct zynqmp_dp *dp,
  * Return: 0 if vs and emph are updated successfully, or the error code returned
  * by drm_dp_dpcd_write().
  */
-static int zynqmp_dp_update_vs_emph(struct zynqmp_dp *dp)
+static int zynqmp_dp_update_vs_emph(struct zynqmp_dp *dp, u8 *train_set)
 {
 	unsigned int i;
 	int ret;
 
-	ret = drm_dp_dpcd_write(&dp->aux, DP_TRAINING_LANE0_SET, dp->train_set,
+	ret = drm_dp_dpcd_write(&dp->aux, DP_TRAINING_LANE0_SET, train_set,
 				dp->mode.lane_cnt);
 	if (ret < 0)
 		return ret;
@@ -655,7 +656,7 @@ static int zynqmp_dp_update_vs_emph(struct zynqmp_dp *dp)
 	for (i = 0; i < dp->mode.lane_cnt; i++) {
 		u32 reg = ZYNQMP_DP_SUB_TX_PHY_PRECURSOR_LANE_0 + i * 4;
 		union phy_configure_opts opts = { 0 };
-		u8 train = dp->train_set[i];
+		u8 train = train_set[i];
 
 		opts.dp.voltage[0] = (train & DP_TRAIN_VOLTAGE_SWING_MASK)
 				   >> DP_TRAIN_VOLTAGE_SWING_SHIFT;
@@ -699,7 +700,7 @@ static int zynqmp_dp_link_train_cr(struct zynqmp_dp *dp)
 	 * So, This loop should exit before 512 iterations
 	 */
 	for (max_tries = 0; max_tries < 512; max_tries++) {
-		ret = zynqmp_dp_update_vs_emph(dp);
+		ret = zynqmp_dp_update_vs_emph(dp, dp->train_set);
 		if (ret)
 			return ret;
 
@@ -764,7 +765,7 @@ static int zynqmp_dp_link_train_ce(struct zynqmp_dp *dp)
 		return ret;
 
 	for (tries = 0; tries < DP_MAX_TRAINING_TRIES; tries++) {
-		ret = zynqmp_dp_update_vs_emph(dp);
+		ret = zynqmp_dp_update_vs_emph(dp, dp->train_set);
 		if (ret)
 			return ret;
 
@@ -787,28 +788,29 @@ static int zynqmp_dp_link_train_ce(struct zynqmp_dp *dp)
 }
 
 /**
- * zynqmp_dp_train - Train the link
+ * zynqmp_dp_setup() - Set up major link parameters
  * @dp: DisplayPort IP core structure
+ * @bw_code: The link bandwidth as a multiple of 270 MHz
+ * @lane_cnt: The number of lanes to use
+ * @enhanced: Use enhanced framing
+ * @downspread: Enable spread-spectrum clocking
  *
- * Return: 0 if all trains are done successfully, or corresponding error code.
+ * Return: 0 on success, or -errno on failure
  */
-static int zynqmp_dp_train(struct zynqmp_dp *dp)
+static int zynqmp_dp_setup(struct zynqmp_dp *dp, u8 bw_code, u8 lane_cnt,
+			   bool enhanced, bool downspread)
 {
 	u32 reg;
-	u8 bw_code = dp->mode.bw_code;
-	u8 lane_cnt = dp->mode.lane_cnt;
 	u8 aux_lane_cnt = lane_cnt;
-	bool enhanced;
 	int ret;
 
 	zynqmp_dp_write(dp, ZYNQMP_DP_LANE_COUNT_SET, lane_cnt);
-	enhanced = drm_dp_enhanced_frame_cap(dp->dpcd);
 	if (enhanced) {
 		zynqmp_dp_write(dp, ZYNQMP_DP_ENHANCED_FRAME_EN, 1);
 		aux_lane_cnt |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
 	}
 
-	if (dp->dpcd[3] & 0x1) {
+	if (downspread) {
 		zynqmp_dp_write(dp, ZYNQMP_DP_DOWNSPREAD_CTL, 1);
 		drm_dp_dpcd_writeb(&dp->aux, DP_DOWNSPREAD_CTRL,
 				   DP_SPREAD_AMP_0_5);
@@ -851,8 +853,25 @@ static int zynqmp_dp_train(struct zynqmp_dp *dp)
 	}
 
 	zynqmp_dp_write(dp, ZYNQMP_DP_PHY_CLOCK_SELECT, reg);
-	ret = zynqmp_dp_phy_ready(dp);
-	if (ret < 0)
+	return zynqmp_dp_phy_ready(dp);
+}
+
+
+/**
+ * zynqmp_dp_train - Train the link
+ * @dp: DisplayPort IP core structure
+ *
+ * Return: 0 if all trains are done successfully, or corresponding error code.
+ */
+static int zynqmp_dp_train(struct zynqmp_dp *dp)
+{
+	int ret;
+
+	ret = zynqmp_dp_setup(dp, dp->mode.bw_code, dp->mode.lane_cnt,
+			      drm_dp_enhanced_frame_cap(dp->dpcd),
+			      dp->dpcd[DP_MAX_DOWNSPREAD] &
+			      DP_MAX_DOWNSPREAD_0_5);
+	if (ret)
 		return ret;
 
 	zynqmp_dp_write(dp, ZYNQMP_DP_SCRAMBLING_DISABLE, 1);
-- 
2.35.1.1320.gc452695387.dirty