[PATCH 4.18 166/197] drm/amd/display: update clk for various HDMI color depths

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mikita Lipski <mikita.lipski@xxxxxxx>

commit 81aca8e75c1b046865fb2badef95a0dcff6f73de upstream.

[why]
When programming tonga's connector's backend we didn't take
in account that HDMI's colour depth might be more than 8bpc
therefore we need to add a switch statement that would adjust
the pixel clock accordingly.

[how]
Add a switch statement updating clock by its appropriate
coefficient.

Signed-off-by: Mikita Lipski <mikita.lipski@xxxxxxx>
Reviewed-by: Charlene Liu <Charlene.Liu@xxxxxxx>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/gpu/drm/amd/display/dc/bios/command_table.c |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

--- a/drivers/gpu/drm/amd/display/dc/bios/command_table.c
+++ b/drivers/gpu/drm/amd/display/dc/bios/command_table.c
@@ -808,6 +808,24 @@ static enum bp_result transmitter_contro
 	 * (=1: 8bpp, =1.25: 10bpp, =1.5:12bpp, =2: 16bpp)
 	 * LVDS mode: usPixelClock = pixel clock
 	 */
+	if  (cntl->signal == SIGNAL_TYPE_HDMI_TYPE_A) {
+		switch (cntl->color_depth) {
+		case COLOR_DEPTH_101010:
+			params.usSymClock =
+				cpu_to_le16((le16_to_cpu(params.usSymClock) * 30) / 24);
+			break;
+		case COLOR_DEPTH_121212:
+			params.usSymClock =
+				cpu_to_le16((le16_to_cpu(params.usSymClock) * 36) / 24);
+			break;
+		case COLOR_DEPTH_161616:
+			params.usSymClock =
+				cpu_to_le16((le16_to_cpu(params.usSymClock) * 48) / 24);
+			break;
+		default:
+			break;
+		}
+	}
 
 	if (EXEC_BIOS_CMD_TABLE(UNIPHYTransmitterControl, params))
 		result = BP_RESULT_OK;