drm/dsi: Add mipi_dsi_set_maximum_return_packet_size() helper

This function can be used to set the maximum return packet size for a
MIPI DSI peripheral.

Signed-off-by: YoungJun Cho <yj44.cho@samsung.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
[treding: endianess, kerneldoc, return value]
Signed-off-by: Thierry Reding <treding@nvidia.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index 388c3ab02500..60177a3e16be 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -332,6 +332,30 @@ int mipi_dsi_create_packet(struct mipi_dsi_packet *packet,
 }
 EXPORT_SYMBOL(mipi_dsi_create_packet);
 
+/*
+ * mipi_dsi_set_maximum_return_packet_size() - specify the maximum size of the
+ *    the payload in a long packet transmitted from the peripheral back to the
+ *    host processor
+ * @dsi: DSI peripheral device
+ * @value: the maximum size of the payload
+ *
+ * Return: 0 on success or a negative error code on failure.
+ */
+int mipi_dsi_set_maximum_return_packet_size(struct mipi_dsi_device *dsi,
+                                            u16 value)
+{
+        u8 tx[2] = { value & 0xff, value >> 8 };
+        struct mipi_dsi_msg msg = {
+                .channel = dsi->channel,
+                .type = MIPI_DSI_SET_MAXIMUM_RETURN_PACKET_SIZE,
+                .tx_len = sizeof(tx),
+                .tx_buf = tx,
+        };
+
+        return mipi_dsi_device_transfer(dsi, &msg);
+}
+EXPORT_SYMBOL(mipi_dsi_set_maximum_return_packet_size);
+
 /**
  * mipi_dsi_dcs_write_buffer() - transmit a DCS command with payload
  * @dsi: DSI peripheral device