drm/mediatek: mtk_dsi: Add support for High Speed (HS) mode

Up until now, the MediaTek DSI Controller has always been working
in Low Power Mode (LPM), as this driver has always ignored the
MIPI_DSI_MSG_USE_LPM flag hence never setting HS mode.

In the current state of the driver the only thing that is needed
to add support for DSI High Speed (HS) transmit is to simply set
the "HSTX" config bit in the configuration register.

Check if flag MIPI_DSI_MSG_USE_LPM is set and, if not, set HSTX.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: Gary Bisson <bisson.gary@gmail.com>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20260108101959.14872-1-angelogioacchino.delregno@collabora.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

Author: AngeloGioacchino Del Regno

drivers/gpu/drm/mediatek/mtk_dsi.c

@@ -152,6 +152,7 @@
 #define SHORT_PACKET			0
 #define LONG_PACKET			2
 #define BTA				BIT(2)
+#define HSTX				BIT(3)
 #define DATA_ID				GENMASK(15, 8)
 #define DATA_0				GENMASK(23, 16)
 #define DATA_1				GENMASK(31, 24)
@@ -1080,6 +1081,9 @@ static void mtk_dsi_cmdq(struct mtk_dsi *dsi, const struct mipi_dsi_msg *msg)
 	else
 		config = (msg->tx_len > 2) ? LONG_PACKET : SHORT_PACKET;
 
+	if (!(msg->flags & MIPI_DSI_MSG_USE_LPM))
+		config |= HSTX;
+
 	if (msg->tx_len > 2) {
 		cmdq_size = 1 + (msg->tx_len + 3) / 4;
 		cmdq_off = 4;