From cbe0dba01d39c008cff6460bfcb1366801b4a41c Mon Sep 17 00:00:00 2001 From: Xinliang Liu Date: Wed, 15 Feb 2017 17:19:08 +0100 Subject: [PATCH 04/93] drm/fb-helper: Add multi buffer support for cma fbdev 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 [s.christ@phytec.de: Picking patch from https://lkml.org/lkml/2015/9/14/188] Signed-off-by: Stefan Christ Signed-off-by: Maxime Ripard --- drivers/gpu/drm/Kconfig | 9 +++++++++ drivers/gpu/drm/drm_fb_helper.c | 10 ++++++++++ 2 files changed, 19 insertions(+) diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index ebfe840..700c8b8 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -84,6 +84,15 @@ config DRM_FBDEV_EMULATION If in doubt, say "Y". +config DRM_FBDEV_OVERALLOC + int "Overallocation of the fbdev buffer" + depends on DRM_FBDEV_EMULATION + default 100 + help + Defines the fbdev buffer overallocation in percent. Default + is 100. Typical values for double buffering will be 200, + triple buffering 300. + config DRM_LOAD_EDID_FIRMWARE bool "Allow to specify an EDID data set instead of probing for it" depends on DRM_KMS_HELPER diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index e934b54..c6de87a 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -48,6 +48,12 @@ MODULE_PARM_DESC(fbdev_emulation, "Enable legacy fbdev emulation [default=true]"); +static int drm_fbdev_overalloc = CONFIG_DRM_FBDEV_OVERALLOC; +module_param(drm_fbdev_overalloc, int, 0444); +MODULE_PARM_DESC(drm_fbdev_overalloc, + "Overallocation of the fbdev buffer (%) [default=" + __MODULE_STRING(CONFIG_DRM_FBDEV_OVERALLOC) "]"); + static LIST_HEAD(kernel_fb_helper_list); static DEFINE_MUTEX(kernel_fb_helper_lock); @@ -1573,6 +1579,10 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper, sizes.fb_height = sizes.surface_height = 768; } + /* Handle our overallocation */ + sizes.surface_height *= drm_fbdev_overalloc; + sizes.surface_height /= 100; + /* push down into drivers */ ret = (*fb_helper->funcs->fb_probe)(fb_helper, &sizes); if (ret < 0) -- 1.9.1