[PATCH v3] drm/dsi: Implement set tear scanline

[Vinay Simha BN]

Provide a small convenience wrapper that transmits
a set_tear_scanline command.

Cc: Archit Taneja <archit.taneja at gmail.com>
Cc: John Stultz <john.stultz at linaro.org>
Cc: Thierry Reding <thierry.reding at gmail.com>
Cc: Sumit Semwal <sumit.semwal at linaro.org>
Cc: Jani Nikula <jani.nikula at linux.intel.com>
Signed-off-by: Vinay Simha BN <simhavcs at gmail.com>

--
v1:
  * helper function suggested by Thierry
    for set_tear_scanline
  * Also includes small build fixes from Sumit Semwal.

v2:
  * one scanline parameter suggested by jani

v3:
  * passing the payload properly as suggested by jani
--
---
 drivers/gpu/drm/drm_mipi_dsi.c | 22 ++++++++++++++++++++++
 include/drm/drm_mipi_dsi.h     |  1 +
 2 files changed, 23 insertions(+)

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index f5d8083..7938ce7 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -983,6 +983,28 @@ int mipi_dsi_dcs_set_tear_on(struct mipi_dsi_device *dsi,
 EXPORT_SYMBOL(mipi_dsi_dcs_set_tear_on);
 
 /**
+ * mipi_dsi_set_tear_scanline() - turn on the display module's Tearing Effect
+ * output signal on the TE signal line when display module reaches line N
+ * defined by STS[n:0].
+ * @dsi: DSI peripheral device
+ * @param: STS[10:0]
+ * Return: 0 on success or a negative error code on failure
+ */
+int mipi_dsi_set_tear_scanline(struct mipi_dsi_device *dsi, u16 param)
+{
+	u8 payload[3] = { MIPI_DCS_SET_TEAR_SCANLINE, param >> 8,
+			  param & 0xff };
+	ssize_t err;
+
+	err = mipi_dsi_generic_write(dsi, payload, sizeof(payload));
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+EXPORT_SYMBOL(mipi_dsi_set_tear_scanline);
+
+/**
  * mipi_dsi_dcs_set_pixel_format() - sets the pixel format for the RGB image
  *    data used by the interface
  * @dsi: DSI peripheral device
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index 7a9840f..ec55285 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -263,6 +263,7 @@ int mipi_dsi_dcs_set_column_address(struct mipi_dsi_device *dsi, u16 start,
 				    u16 end);
 int mipi_dsi_dcs_set_page_address(struct mipi_dsi_device *dsi, u16 start,
 				  u16 end);
+int mipi_dsi_set_tear_scanline(struct mipi_dsi_device *dsi, u16 param);
 int mipi_dsi_dcs_set_tear_off(struct mipi_dsi_device *dsi);
 int mipi_dsi_dcs_set_tear_on(struct mipi_dsi_device *dsi,
 			     enum mipi_dsi_dcs_tear_mode mode);
-- 
2.1.2