drm/xen-front: Remove CMA support

It turns out this was only needed to paper over a bug in the CMA
helpers, which was addressed in

commit 998fb1a0f478b83492220ff79583bf9ad538bdd8
Author: Liviu Dudau <Liviu.Dudau@arm.com>
Date:   Fri Nov 10 13:33:10 2017 +0000

    drm: gem_cma_helper.c: Allow importing of contiguous scatterlists with nents > 1

Without this the following pipeline didn't work:

domU:
1. xen-front allocates a non-contig buffer
2. creates grants out of it

dom0:
3. converts the grants into a dma-buf. Since they're non-contig, the
scatter-list is huge.
4. imports it into rcar-du, which requires dma-contig memory for
scanout.

-> On this given platform there's an IOMMU, so in theory this should
work. But in practice this failed, because of the huge number of sg
entries, even though the IOMMU driver mapped it all into a dma-contig
range.

With a guest-contig buffer allocated in step 1, this problem doesn't
exist. But there's technically no reason to require guest-contig
memory for xen buffer sharing using grants.

Given all that, the xen-front cma support is not needed and should be
removed.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180417074012.21311-1-andr2000@gmail.com

1 files changed, 10 insertions, 52 deletions

diff --git a/drivers/gpu/drm/xen/xen_drm_front.c b/drivers/gpu/drm/xen/xen_drm_front.c
index 4a08b77f1c9e..1b0ea9ac330e 100644
--- a/drivers/gpu/drm/xen/xen_drm_front.c
+++ b/drivers/gpu/drm/xen/xen_drm_front.c
@@ -12,7 +12,6 @@
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_gem.h>
-#include <drm/drm_gem_cma_helper.h>
 
 #include <linux/of_device.h>
 
@@ -167,10 +166,9 @@ int xen_drm_front_mode_set(struct xen_drm_front_drm_pipeline *pipeline,
 	return ret;
 }
 
-static int be_dbuf_create_int(struct xen_drm_front_info *front_info,
+int xen_drm_front_dbuf_create(struct xen_drm_front_info *front_info,
 			      u64 dbuf_cookie, u32 width, u32 height,
-			      u32 bpp, u64 size, struct page **pages,
-			      struct sg_table *sgt)
+			      u32 bpp, u64 size, struct page **pages)
 {
 	struct xen_drm_front_evtchnl *evtchnl;
 	struct xen_drm_front_shbuf *shbuf;
@@ -187,7 +185,6 @@ static int be_dbuf_create_int(struct xen_drm_front_info *front_info,
 	buf_cfg.xb_dev = front_info->xb_dev;
 	buf_cfg.pages = pages;
 	buf_cfg.size = size;
-	buf_cfg.sgt = sgt;
 	buf_cfg.be_alloc = front_info->cfg.be_alloc;
 
 	shbuf = xen_drm_front_shbuf_alloc(&buf_cfg);
@@ -237,22 +234,6 @@ fail:
 	return ret;
 }
 
-int xen_drm_front_dbuf_create_from_sgt(struct xen_drm_front_info *front_info,
-				       u64 dbuf_cookie, u32 width, u32 height,
-				       u32 bpp, u64 size, struct sg_table *sgt)
-{
-	return be_dbuf_create_int(front_info, dbuf_cookie, width, height,
-				  bpp, size, NULL, sgt);
-}
-
-int xen_drm_front_dbuf_create_from_pages(struct xen_drm_front_info *front_info,
-					 u64 dbuf_cookie, u32 width, u32 height,
-					 u32 bpp, u64 size, struct page **pages)
-{
-	return be_dbuf_create_int(front_info, dbuf_cookie, width, height,
-				  bpp, size, pages, NULL);
-}
-
 static int xen_drm_front_dbuf_destroy(struct xen_drm_front_info *front_info,
 				      u64 dbuf_cookie)
 {
@@ -434,24 +415,11 @@ static int xen_drm_drv_dumb_create(struct drm_file *filp,
 		goto fail;
 	}
 
-	/*
-	 * In case of CONFIG_DRM_XEN_FRONTEND_CMA gem_obj is constructed
-	 * via DRM CMA helpers and doesn't have ->pages allocated
-	 * (xendrm_gem_get_pages will return NULL), but instead can provide
-	 * sg table
-	 */
-	if (xen_drm_front_gem_get_pages(obj))
-		ret = xen_drm_front_dbuf_create_from_pages(drm_info->front_info,
-				xen_drm_front_dbuf_to_cookie(obj),
-				args->width, args->height, args->bpp,
-				args->size,
-				xen_drm_front_gem_get_pages(obj));
-	else
-		ret = xen_drm_front_dbuf_create_from_sgt(drm_info->front_info,
-				xen_drm_front_dbuf_to_cookie(obj),
-				args->width, args->height, args->bpp,
-				args->size,
-				xen_drm_front_gem_get_sg_table(obj));
+	ret = xen_drm_front_dbuf_create(drm_info->front_info,
+					xen_drm_front_dbuf_to_cookie(obj),
+					args->width, args->height, args->bpp,
+					args->size,
+					xen_drm_front_gem_get_pages(obj));
 	if (ret)
 		goto fail_backend;
 
@@ -523,11 +491,7 @@ static const struct file_operations xen_drm_dev_fops = {
 	.poll           = drm_poll,
 	.read           = drm_read,
 	.llseek         = no_llseek,
-#ifdef CONFIG_DRM_XEN_FRONTEND_CMA
-	.mmap           = drm_gem_cma_mmap,
-#else
 	.mmap           = xen_drm_front_gem_mmap,
-#endif
 };
 
 static const struct vm_operations_struct xen_drm_drv_vm_ops = {
@@ -547,6 +511,9 @@ static struct drm_driver xen_drm_driver = {
 	.gem_prime_export          = drm_gem_prime_export,
 	.gem_prime_import_sg_table = xen_drm_front_gem_import_sg_table,
 	.gem_prime_get_sg_table    = xen_drm_front_gem_get_sg_table,
+	.gem_prime_vmap            = xen_drm_front_gem_prime_vmap,
+	.gem_prime_vunmap          = xen_drm_front_gem_prime_vunmap,
+	.gem_prime_mmap            = xen_drm_front_gem_prime_mmap,
 	.dumb_create               = xen_drm_drv_dumb_create,
 	.fops                      = &xen_drm_dev_fops,
 	.name                      = "xendrm-du",
@@ -555,15 +522,6 @@ static struct drm_driver xen_drm_driver = {
 	.major                     = 1,
 	.minor                     = 0,
 
-#ifdef CONFIG_DRM_XEN_FRONTEND_CMA
-	.gem_prime_vmap            = drm_gem_cma_prime_vmap,
-	.gem_prime_vunmap          = drm_gem_cma_prime_vunmap,
-	.gem_prime_mmap            = drm_gem_cma_prime_mmap,
-#else
-	.gem_prime_vmap            = xen_drm_front_gem_prime_vmap,
-	.gem_prime_vunmap          = xen_drm_front_gem_prime_vunmap,
-	.gem_prime_mmap            = xen_drm_front_gem_prime_mmap,
-#endif
 };
 
 static int xen_drm_drv_init(struct xen_drm_front_info *front_info)