[PATCH v3 11/13] drm: zynqmp_dp: Split off several helper functions

Sean Anderson
2024-04-22T18:46:23Z

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 3d90533aefd7..364caaf26f49 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