drm/rockchip: Respect page offset for PRIME mmap calls

[ Upstream commit 57de50af162b67612da99207b061ade3239e57db ]

When mapping external DMA-bufs through the PRIME mmap call, we might be
given an offset which has to be respected. However for the internal DRM
GEM mmap path, we have to ignore the fake mmap offset used to identify
the buffer only. Currently the code always zeroes out vma->vm_pgoff,
which breaks the former.

This patch fixes the problem by moving the vm_pgoff assignment to a
function that is used only for GEM mmap path, so that the PRIME path
retains the original offset.

Cc: Daniel Kurtz <djkurtz@chromium.org>
Signed-off-by: Ørjan Eide <orjan.eide@arm.com>
Signed-off-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20180130202913.28724-4-thierry.escande@collabora.com
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
index 1869c8bb76c8173677be56c1d68a8364cf80a1f2..bde65186a3c37d16a1d06ed4418faad3f333a2a0 100644 (file)
--- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
@@ -262,7 +262,6 @@ static int rockchip_drm_gem_object_mmap(struct drm_gem_object *obj,
         * VM_PFNMAP flag that was set by drm_gem_mmap_obj()/drm_gem_mmap().
         */
        vma->vm_flags &= ~VM_PFNMAP;
-       vma->vm_pgoff = 0;
 
        if (rk_obj->pages)
                ret = rockchip_drm_gem_object_mmap_iommu(obj, vma);
@@ -297,6 +296,12 @@ int rockchip_gem_mmap(struct file *filp, struct vm_area_struct *vma)
        if (ret)
                return ret;
 
+       /*
+        * Set vm_pgoff (used as a fake buffer offset by DRM) to 0 and map the
+        * whole buffer from the start.
+        */
+       vma->vm_pgoff = 0;
+
        obj = vma->vm_private_data;
 
        return rockchip_drm_gem_object_mmap(obj, vma);