From: Ben Skeggs <bskeggs@redhat.com>
Date: Fri, 12 Jan 2018 17:50:37 +1000
Subject: drm/nouveau/fbcon: add module parameter to select bits-per-pixel
Git-commit: 27cda223327505a19d912536dff205ccdc5c5c2a
Patch-mainline: v4.16-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

Useful for debugging.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/nouveau/nouveau_fbcon.c |   22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

--- a/drivers/gpu/drm/nouveau/nouveau_fbcon.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
@@ -56,6 +56,10 @@ MODULE_PARM_DESC(nofbaccel, "Disable fbc
 int nouveau_nofbaccel = 0;
 module_param_named(nofbaccel, nouveau_nofbaccel, int, 0400);
 
+MODULE_PARM_DESC(fbcon_bpp, "fbcon bits-per-pixel (default: auto)");
+static int nouveau_fbcon_bpp;
+module_param_named(fbcon_bpp, nouveau_fbcon_bpp, int, 0400);
+
 static void
 nouveau_fbcon_fillrect(struct fb_info *info, const struct fb_fillrect *rect)
 {
@@ -488,7 +492,7 @@ nouveau_fbcon_init(struct drm_device *de
 {
 	struct nouveau_drm *drm = nouveau_drm(dev);
 	struct nouveau_fbdev *fbcon;
-	int preferred_bpp;
+	int preferred_bpp = nouveau_fbcon_bpp;
 	int ret;
 
 	if (!dev->mode_config.num_crtc ||
@@ -512,13 +516,15 @@ nouveau_fbcon_init(struct drm_device *de
 	if (ret)
 		goto fini;
 
-	if (drm->client.device.info.ram_size <= 32 * 1024 * 1024)
-		preferred_bpp = 8;
-	else
-	if (drm->client.device.info.ram_size <= 64 * 1024 * 1024)
-		preferred_bpp = 16;
-	else
-		preferred_bpp = 32;
+	if (preferred_bpp != 8 && preferred_bpp != 16 && preferred_bpp != 32) {
+		if (drm->client.device.info.ram_size <= 32 * 1024 * 1024)
+			preferred_bpp = 8;
+		else
+		if (drm->client.device.info.ram_size <= 64 * 1024 * 1024)
+			preferred_bpp = 16;
+		else
+			preferred_bpp = 32;
+	}
 
 	/* disable all the possible outputs/crtcs before entering KMS mode */
 	if (!drm_drv_uses_atomic_modeset(dev))