linux-kernel - [PATCH 1/2] drm/bridge: samsung-dsim: use while loop in samsung_dsim_transfer

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Message-Id: <20250527-samsung-dsim-v1-1-5be520d84fbb@pengutronix.de>
Date: Tue, 27 May 2025 16:21:47 +0200
From: Philipp Zabel <p.zabel@...gutronix.de>
To: Inki Dae <inki.dae@...sung.com>, 
 Jagan Teki <jagan@...rulasolutions.com>, 
 Marek Szyprowski <m.szyprowski@...sung.com>, 
 Andrzej Hajda <andrzej.hajda@...el.com>, 
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 kernel@...gutronix.de, Philipp Zabel <p.zabel@...gutronix.de>
Subject: [PATCH 1/2] drm/bridge: samsung-dsim: use while loop in
 samsung_dsim_transfer_start

Turn the open-coded goto-again construct into a while loop, to make
samsung_dsim_transfer_start() a bit shorter and easier to read.

Hold the spinlock when looping back around and avoid the duplicated
list_empty() check.

Signed-off-by: Philipp Zabel <p.zabel@...gutronix.de>
---
 drivers/gpu/drm/bridge/samsung-dsim.c | 51 +++++++++++++++--------------------
 1 file changed, 21 insertions(+), 30 deletions(-)

diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
index 0014c497e3fe7d8349a119dbdda30d65d816cccf..1dfc9710bee5134e0e0114ce52f673c21564b11b 100644
--- a/drivers/gpu/drm/bridge/samsung-dsim.c
+++ b/drivers/gpu/drm/bridge/samsung-dsim.c
@@ -1235,43 +1235,34 @@ static void samsung_dsim_transfer_start(struct samsung_dsim *dsi)
 {
 	unsigned long flags;
 	struct samsung_dsim_transfer *xfer;
-	bool start = false;
 
-again:
 	spin_lock_irqsave(&dsi->transfer_lock, flags);
 
-	if (list_empty(&dsi->transfer_list)) {
+	while (!list_empty(&dsi->transfer_list)) {
+		xfer = list_first_entry(&dsi->transfer_list,
+					struct samsung_dsim_transfer, list);
+
 		spin_unlock_irqrestore(&dsi->transfer_lock, flags);
-		return;
+
+		if (xfer->packet.payload_length &&
+		    xfer->tx_done == xfer->packet.payload_length)
+			/* waiting for RX */
+			return;
+
+		samsung_dsim_send_to_fifo(dsi, xfer);
+
+		if (xfer->packet.payload_length || xfer->rx_len)
+			return;
+
+		xfer->result = 0;
+		complete(&xfer->completed);
+
+		spin_lock_irqsave(&dsi->transfer_lock, flags);
+
+		list_del_init(&xfer->list);
 	}
 
-	xfer = list_first_entry(&dsi->transfer_list,
-				struct samsung_dsim_transfer, list);
-
 	spin_unlock_irqrestore(&dsi->transfer_lock, flags);
-
-	if (xfer->packet.payload_length &&
-	    xfer->tx_done == xfer->packet.payload_length)
-		/* waiting for RX */
-		return;
-
-	samsung_dsim_send_to_fifo(dsi, xfer);
-
-	if (xfer->packet.payload_length || xfer->rx_len)
-		return;
-
-	xfer->result = 0;
-	complete(&xfer->completed);
-
-	spin_lock_irqsave(&dsi->transfer_lock, flags);
-
-	list_del_init(&xfer->list);
-	start = !list_empty(&dsi->transfer_list);
-
-	spin_unlock_irqrestore(&dsi->transfer_lock, flags);
-
-	if (start)
-		goto again;
 }
 
 static bool samsung_dsim_transfer_finish(struct samsung_dsim *dsi)

-- 
2.39.5