drm/ttm: Remove TTM_HAS_AGP

It tries to do fancy things with excluding agp support if ttm is
built-in, but agp isn't. Instead just express this depency like drm
does and use CONFIG_AGP everywhere.

Also use the neat Makefile magic to make the entire ttm_agp_backend
file optional.

v2: Use IS_ENABLED(CONFIG_AGP) as suggested by Ville

v3: Review from Emil.

v4: Actually get it right as spotted by 0-day.

Cc: Emil Velikov <emil.l.velikov@gmail.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1459337046-25882-1-git-send-email-daniel.vetter@ffwll.ch

drivers/gpu/drm/ttm/Makefile

@@ -2,9 +2,10 @@
 # Makefile for the drm device driver.  This driver provides support for the
 
 ccflags-y := -Iinclude/drm
-ttm-y := ttm_agp_backend.o ttm_memory.o ttm_tt.o ttm_bo.o \
+ttm-y := ttm_memory.o ttm_tt.o ttm_bo.o \
 	ttm_bo_util.o ttm_bo_vm.o ttm_module.o \
 	ttm_object.o ttm_lock.o ttm_execbuf_util.o ttm_page_alloc.o \
 	ttm_bo_manager.o ttm_page_alloc_dma.o
+ttm-$(CONFIG_AGP) += ttm_agp_backend.o
 
 obj-$(CONFIG_DRM_TTM) += ttm.o

drivers/gpu/drm/ttm/ttm_agp_backend.c

@@ -34,7 +34,6 @@
 #include <drm/ttm/ttm_module.h>
 #include <drm/ttm/ttm_bo_driver.h>
 #include <drm/ttm/ttm_page_alloc.h>
-#ifdef TTM_HAS_AGP
 #include <drm/ttm/ttm_placement.h>
 #include <linux/agp_backend.h>
 #include <linux/module.h>
@@ -148,5 +147,3 @@ void ttm_agp_tt_unpopulate(struct ttm_tt *ttm)
 	ttm_pool_unpopulate(ttm);
 }
 EXPORT_SYMBOL(ttm_agp_tt_unpopulate);
-
-#endif

drivers/gpu/drm/ttm/ttm_page_alloc.c

@@ -48,7 +48,7 @@
 #include <drm/ttm/ttm_bo_driver.h>
 #include <drm/ttm/ttm_page_alloc.h>
 
-#ifdef TTM_HAS_AGP
+#if IS_ENABLED(CONFIG_AGP)
 #include <asm/agp.h>
 #endif
 
@@ -219,7 +219,7 @@ static struct ttm_pool_manager *_manager;
 #ifndef CONFIG_X86
 static int set_pages_array_wb(struct page **pages, int addrinarray)
 {
-#ifdef TTM_HAS_AGP
+#if IS_ENABLED(CONFIG_AGP)
 	int i;
 
 	for (i = 0; i < addrinarray; i++)
@@ -230,7 +230,7 @@ static int set_pages_array_wb(struct page **pages, int addrinarray)
 
 static int set_pages_array_wc(struct page **pages, int addrinarray)
 {
-#ifdef TTM_HAS_AGP
+#if IS_ENABLED(CONFIG_AGP)
 	int i;
 
 	for (i = 0; i < addrinarray; i++)
@@ -241,7 +241,7 @@ static int set_pages_array_wc(struct page **pages, int addrinarray)
 
 static int set_pages_array_uc(struct page **pages, int addrinarray)
 {
-#ifdef TTM_HAS_AGP
+#if IS_ENABLED(CONFIG_AGP)
 	int i;
 
 	for (i = 0; i < addrinarray; i++)

drivers/gpu/drm/ttm/ttm_page_alloc_dma.c

@@ -50,7 +50,7 @@
 #include <linux/kthread.h>
 #include <drm/ttm/ttm_bo_driver.h>
 #include <drm/ttm/ttm_page_alloc.h>
-#ifdef TTM_HAS_AGP
+#if IS_ENABLED(CONFIG_AGP)
 #include <asm/agp.h>
 #endif
 
@@ -271,7 +271,7 @@ static struct kobj_type ttm_pool_kobj_type = {
 #ifndef CONFIG_X86
 static int set_pages_array_wb(struct page **pages, int addrinarray)
 {
-#ifdef TTM_HAS_AGP
+#if IS_ENABLED(CONFIG_AGP)
 	int i;
 
 	for (i = 0; i < addrinarray; i++)
@@ -282,7 +282,7 @@ static int set_pages_array_wb(struct page **pages, int addrinarray)
 
 static int set_pages_array_wc(struct page **pages, int addrinarray)
 {
-#ifdef TTM_HAS_AGP
+#if IS_ENABLED(CONFIG_AGP)
 	int i;
 
 	for (i = 0; i < addrinarray; i++)
@@ -293,7 +293,7 @@ static int set_pages_array_wc(struct page **pages, int addrinarray)
 
 static int set_pages_array_uc(struct page **pages, int addrinarray)
 {
-#ifdef TTM_HAS_AGP
+#if IS_ENABLED(CONFIG_AGP)
 	int i;
 
 	for (i = 0; i < addrinarray; i++)

include/drm/ttm/ttm_bo_driver.h

@@ -1030,8 +1030,7 @@ extern pgprot_t ttm_io_prot(uint32_t caching_flags, pgprot_t tmp);
 
 extern const struct ttm_mem_type_manager_func ttm_bo_manager_func;
 
-#if (defined(CONFIG_AGP) || (defined(CONFIG_AGP_MODULE) && defined(MODULE)))
-#define TTM_HAS_AGP
+#if IS_ENABLED(CONFIG_AGP)
 #include <linux/agp_backend.h>
 
 /**