[Xen-devel] [PATCH 09/11] ttm: Add 'no_dma' parameter to turn the TTM DMA pool off during runtime.

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

The TTM DMA only gets turned on when the SWIOTLB is enabled - but
we might also want to turn it off when SWIOTLB is on to
use the non-DMA TTM pool code.

In the future this parameter can be removed.

Reviewed-by: Jerome Glisse <jglisse@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 drivers/gpu/drm/ttm/ttm_memory.c         |    7 +++++--
 drivers/gpu/drm/ttm/ttm_page_alloc_dma.c |    6 +++++-
 include/drm/ttm/ttm_page_alloc.h         |    2 ++
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_memory.c b/drivers/gpu/drm/ttm/ttm_memory.c
index 6d24fe2..f883a28 100644
--- a/drivers/gpu/drm/ttm/ttm_memory.c
+++ b/drivers/gpu/drm/ttm/ttm_memory.c
@@ -395,7 +395,9 @@ int ttm_mem_global_init(struct ttm_mem_global *glob)
                       zone->name, (unsigned long long) zone->max_mem >> 10);
        }
        ttm_page_alloc_init(glob, glob->zone_kernel->max_mem/(2*PAGE_SIZE));
-       ttm_dma_page_alloc_init(glob, glob->zone_kernel->max_mem/(2*PAGE_SIZE));
+       if (!ttm_dma_disable)
+               ttm_dma_page_alloc_init(glob, glob->zone_kernel->max_mem /
+                                       (2*PAGE_SIZE));
        return 0;
 out_no_zone:
        ttm_mem_global_release(glob);
@@ -411,7 +413,8 @@ void ttm_mem_global_release(struct ttm_mem_global *glob)
        /* let the page allocator first stop the shrink work. */
        ttm_page_alloc_fini();
 
-       ttm_dma_page_alloc_fini();
+       if (!ttm_dma_disable)
+               ttm_dma_page_alloc_fini();
        flush_workqueue(glob->swap_queue);
        destroy_workqueue(glob->swap_queue);
        glob->swap_queue = NULL;
diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c 
b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
index 5a2d362..cfc8d9f 100644
--- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
@@ -51,6 +51,10 @@
 #include <asm/agp.h>
 #endif
 
+int __read_mostly ttm_dma_disable;
+MODULE_PARM_DESC(no_dma, "Disable TTM DMA pool");
+module_param_named(no_dma, ttm_dma_disable, bool, S_IRUGO);
+
 #define NUM_PAGES_TO_ALLOC             (PAGE_SIZE/sizeof(struct page *))
 #define SMALL_ALLOCATION               16
 #define FREE_ALL_PAGES                 (~0U)
@@ -1395,7 +1399,7 @@ int ttm_dma_page_alloc_debugfs(struct seq_file *m, void 
*data)
 EXPORT_SYMBOL_GPL(ttm_dma_page_alloc_debugfs);
 bool ttm_dma_override(struct ttm_backend_func *be)
 {
-       if (swiotlb_nr_tbl() && be) {
+       if (swiotlb_nr_tbl() && be && !ttm_dma_disable) {
                be->get_pages = &ttm_dma_get_pages;
                be->put_pages = &ttm_dma_put_pages;
                return true;
diff --git a/include/drm/ttm/ttm_page_alloc.h b/include/drm/ttm/ttm_page_alloc.h
index 9c52fb7..daf5db6 100644
--- a/include/drm/ttm/ttm_page_alloc.h
+++ b/include/drm/ttm/ttm_page_alloc.h
@@ -32,6 +32,7 @@
 #ifdef CONFIG_SWIOTLB
 extern bool ttm_dma_override(struct ttm_backend_func *be);
 
+extern int ttm_dma_disable;
 /**
  * Initialize pool allocator.
  */
@@ -45,6 +46,7 @@ void ttm_dma_page_alloc_fini(void);
  */
 extern int ttm_dma_page_alloc_debugfs(struct seq_file *m, void *data);
 #else
+#define ttm_dma_disable (1)
 static inline bool ttm_dma_override(struct ttm_backend_func *be)
 {
        return false;
-- 
1.7.6.4


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