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>

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index 388c3ab02500d9ea860690fa91a53ea87177d9ad..60177a3e16be09a4a561df886ae95afbc4387682 100644 (file)
--- 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

diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index 4eeb4a5ead8bdf880d08944307164dcaca090a77..4a4e9d7ccc16723daa2c470cfd59f31f447719ba 100644 (file)
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -153,6 +153,8 @@ static inline struct mipi_dsi_device *to_mipi_dsi_device(struct device *dev)
 
 int mipi_dsi_attach(struct mipi_dsi_device *dsi);
 int mipi_dsi_detach(struct mipi_dsi_device *dsi);
+int mipi_dsi_set_maximum_return_packet_size(struct mipi_dsi_device *dsi,
+                                           u16 value);
 ssize_t mipi_dsi_dcs_write_buffer(struct mipi_dsi_device *dsi,
                                  const void *data, size_t len);
 ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, u8 cmd,