[PATCH 4/4] phy: zynqmp: Only wait for PLL lock "primary" instances

[Sean Anderson]

For PCIe and DisplayPort, the phy instance represents the controller's
logical lane. Wait for the instance 0 phy's PLL to lock as other
instances will never lock. We do this in xpsgtr_wait_pll_lock so callers
don't have to determine the correct lane themselves.

The original comment is wrong about cumulative wait times. Since we are
just polling a bit, all subsequent waiters will finish immediately.

Signed-off-by: Sean Anderson <sean.anderson at linux.dev>
Link: https://lore.kernel.org/r/20240628205540.3098010-4-sean.anderson@linux.dev
Signed-off-by: Vinod Koul <vkoul at kernel.org>
[ Linux commit 235d8b663ab9e6cc13f8374abfffa559f50b57b6 ]
Signed-off-by: Sean Anderson <sean.anderson at linux.dev>
---

 drivers/phy/phy-zynqmp.c | 44 +++++++++++++++++++++-------------------
 1 file changed, 23 insertions(+), 21 deletions(-)

diff --git a/drivers/phy/phy-zynqmp.c b/drivers/phy/phy-zynqmp.c
index 6316f0b7619..e5181c59f29 100644
--- a/drivers/phy/phy-zynqmp.c
+++ b/drivers/phy/phy-zynqmp.c
@@ -454,15 +454,32 @@ static int xpsgtr_init(struct phy *x)
 static int xpsgtr_wait_pll_lock(struct phy *phy)
 {
 	struct xpsgtr_dev *gtr_dev = dev_get_priv(phy->dev);
-	struct xpsgtr_phy *gtr_phy;
-	u32 phy_lane = phy->id;
-	int ret = 0;
+	struct xpsgtr_phy *gtr_phy = &gtr_dev->phys[phy->id];
 	unsigned int timeout = TIMEOUT_US;
-
-	gtr_phy = &gtr_dev->phys[phy_lane];
+	u8 protocol = gtr_phy->protocol;
+	int ret = 0;
 
 	dev_dbg(gtr_dev->dev, "Waiting for PLL lock\n");
 
+	/*
+	 * For DP and PCIe, only the instance 0 PLL is used. Switch to that phy
+	 * so we wait on the right PLL.
+	 */
+	if ((protocol == ICM_PROTOCOL_DP || protocol == ICM_PROTOCOL_PCIE) &&
+	    gtr_phy->instance) {
+		int i;
+
+		for (i = 0; i < NUM_LANES; i++) {
+			gtr_phy = &gtr_dev->phys[i];
+
+			if (gtr_phy->protocol == protocol && !gtr_phy->instance)
+				goto got_phy;
+		}
+
+		return -EBUSY;
+	}
+
+got_phy:
 	while (1) {
 		u32 reg = xpsgtr_read_phy(gtr_phy, L0_PLL_STATUS_READ_1);
 
@@ -489,22 +506,7 @@ static int xpsgtr_wait_pll_lock(struct phy *phy)
 
 static int xpsgtr_power_on(struct phy *phy)
 {
-	struct xpsgtr_dev *gtr_dev = dev_get_priv(phy->dev);
-	struct xpsgtr_phy *gtr_phy;
-	u32 phy_lane = phy->id;
-	int ret = 0;
-
-	gtr_phy = &gtr_dev->phys[phy_lane];
-
-	/*
-	 * Wait for the PLL to lock. For DP, only wait on DP0 to avoid
-	 * cumulating waits for both lanes. The user is expected to initialize
-	 * lane 0 last.
-	 */
-	if (gtr_phy->protocol != ICM_PROTOCOL_DP || !gtr_phy->instance)
-		ret = xpsgtr_wait_pll_lock(phy);
-
-	return ret;
+	return xpsgtr_wait_pll_lock(phy);
 }
 
 /*
-- 
2.35.1.1320.gc452695387.dirty