From: Thierry Reding <treding@nvidia.com>
Date: Wed, 7 Feb 2018 18:45:56 +0100
Subject: drm/tegra: fb: Implement ->fb_mmap() callback
Git-commit: b8f3f500e09c2c457efc2fcbfe8b7f815f2e6a0e
Patch-mainline: v4.17-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

This fixes hangs with legacy applications that use the mmap() syscall on
the fbdev device to map framebuffer memory. The fbdev implementation for
mmap() creates a mapping that conflicts with DRM usage and causes a hang
when the memory is accessed through the mapping.

Reported-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Tested-by: Stefan Agner <stefan@agner.ch>
Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Reported-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/tegra/fb.c |   16 ++++++++++++++++
 1 file changed, 16 insertions(+)

--- a/drivers/gpu/drm/tegra/fb.c
+++ b/drivers/gpu/drm/tegra/fb.c
@@ -224,12 +224,28 @@ unreference:
 }
 
 #ifdef CONFIG_DRM_FBDEV_EMULATION
+static int tegra_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
+{
+	struct drm_fb_helper *helper = info->par;
+	struct tegra_bo *bo;
+	int err;
+
+	bo = tegra_fb_get_plane(helper->fb, 0);
+
+	err = drm_gem_mmap_obj(&bo->gem, bo->gem.size, vma);
+	if (err < 0)
+		return err;
+
+	return __tegra_gem_mmap(&bo->gem, vma);
+}
+
 static struct fb_ops tegra_fb_ops = {
 	.owner = THIS_MODULE,
 	DRM_FB_HELPER_DEFAULT_OPS,
 	.fb_fillrect = drm_fb_helper_sys_fillrect,
 	.fb_copyarea = drm_fb_helper_sys_copyarea,
 	.fb_imageblit = drm_fb_helper_sys_imageblit,
+	.fb_mmap = tegra_fb_mmap,
 };
 
 static int tegra_fbdev_probe(struct drm_fb_helper *helper,