linux-kernel - [PATCH 6/9] ttm: Add 'no_dma' parameter to turn the TTM DMA pool off during runtime.

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Date:	Thu, 29 Sep 2011 16:33:49 -0400
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	linux-kernel@...r.kernel.org, thellstrom@...are.com,
	dri-devel@...ts.freedesktop.org, bskeggs@...hat.com,
	j.glisse@...hat.com, thomas@...pmail.org, airlied@...hat.com,
	airlied@...ux.ie, alexdeucher@...il.com
Cc:	xen-devel@...ts.xensource.com,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: [PATCH 6/9] ttm: Add 'no_dma' parameter to turn the TTM DMA pool off during runtime.

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.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
---
 drivers/gpu/drm/ttm/ttm_page_alloc_dma.c |    4 ++++
 include/drm/ttm/ttm_page_alloc.h         |    4 ++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
index 5a5739c..5909d28 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 dma_ttm_disable;
+MODULE_PARM_DESC(no_dma, "Disable TTM DMA pool");
+module_param_named(no_dma, dma_ttm_disable, bool, S_IRUGO);
+
 #define NUM_PAGES_TO_ALLOC		(PAGE_SIZE/sizeof(struct page *))
 #define SMALL_ALLOCATION		16
 #define FREE_ALL_PAGES			(~0U)
diff --git a/include/drm/ttm/ttm_page_alloc.h b/include/drm/ttm/ttm_page_alloc.h
index a58331d..1dde3bd 100644
--- a/include/drm/ttm/ttm_page_alloc.h
+++ b/include/drm/ttm/ttm_page_alloc.h
@@ -103,10 +103,10 @@ extern struct ttm_page_alloc_func ttm_page_alloc_default;
 #ifdef CONFIG_SWIOTLB
 /* Defined in ttm_page_alloc_dma.c */
 extern struct ttm_page_alloc_func ttm_page_alloc_dma;
-
+extern int dma_ttm_disable;
 static inline bool ttm_page_alloc_need_dma(void)
 {
-	if (swiotlb_nr_tbl()) {
+	if (!dma_ttm_disable && swiotlb_nr_tbl()) {
 		ttm_page_alloc = &ttm_page_alloc_dma;
 		return true;
 	}
-- 
1.7.4.1

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