This patch add a config to support to create multi buffer for cma fbdev. Such as
double buffer and triple buffer.
Cma fbdev is convient to add a legency fbdev. And still many Android devices use
fbdev now and at least double buffer is needed for these Android devices, so
that a buffer flip can be operated. It will need some time for Android device
vendors to abondon legency fbdev. So multi buffer for fbdev is needed.
Signed-off-by: Xinliang Liu <xinliang.liu at linaro.org>
---
drivers/gpu/drm/Kconfig | 8 ++++++++
drivers/gpu/drm/drm_fb_cma_helper.c | 8 +++++++-
2 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 1a0a8df..577f790 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -97,6 +97,14 @@ config DRM_KMS_CMA_HELPER
help
Choose this if you need the KMS CMA helper functions
+config DRM_CMA_FBDEV_BUFFER_NUM
+ int "Cma Fbdev Buffer Number"
+ depends on DRM_KMS_CMA_HELPER
+ default 1
+ help
+ Defines the buffer number of cma fbdev. Default is one buffer.
+ For double buffer please set to 2 and 3 for triple buffer.
+
source "drivers/gpu/drm/i2c/Kconfig"
config DRM_TDFX
diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c
b/drivers/gpu/drm/drm_fb_cma_helper.c
index c19a625..26051b8 100644
--- a/drivers/gpu/drm/drm_fb_cma_helper.c
+++ b/drivers/gpu/drm/drm_fb_cma_helper.c
@@ -25,6 +25,12 @@
#include <drm/drm_fb_cma_helper.h>
#include <linux/module.h>
+#ifdef CONFIG_DRM_CMA_FBDEV_BUFFER_NUM
+#define FBDEV_BUFFER_NUM CONFIG_DRM_CMA_FBDEV_BUFFER_NUM
+#else
+#define FBDEV_BUFFER_NUM 1
+#endif
+
struct drm_fb_cma {
struct drm_framebuffer fb;
struct drm_gem_cma_object *obj[4];
@@ -253,7 +259,7 @@ static int drm_fbdev_cma_create(struct drm_fb_helper
*helper,
bytes_per_pixel = DIV_ROUND_UP(sizes->surface_bpp, 8);
mode_cmd.width = sizes->surface_width;
- mode_cmd.height = sizes->surface_height;
+ mode_cmd.height = sizes->surface_height * FBDEV_BUFFER_NUM;
mode_cmd.pitches[0] = sizes->surface_width * bytes_per_pixel;
mode_cmd.pixel_format = drm_mode_legacy_fb_format(sizes->surface_bpp,
sizes->surface_depth);
--
1.9.1
