[PATCH 4/5] kdb,kms: Save and restore the LUT on atomic KMS enter/exit

Jason Wessel
2010-10-12T18:16:19Z

When changing VTs non-atomically the kernel works in conjunction with
the Xserver in user space and receives the LUT information from the
Xserver via a system call. When changing modes atomically for kdb,
this information must be saved and restored without disturbing user
space as if nothing ever happened.

There is a short cut used by this patch where gamma_store is used as
the save space. If this turns out to be a problem in the future a
pre-allocated chunk of memory will be required for each crtc to save
and restore the LUT information.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
CC: Jesse Barnes <jbarnes@virtuousgeek.org>
CC: David Airlie <airlied@linux.ie>
CC: dri-devel@lists.freedesktop.org
---
drivers/gpu/drm/drm_fb_helper.c | 31 +++++++++++++++++++++++++++++++
1 files changed, 31 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 74bac82..5c8fbfa 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -242,6 +242,34 @@ static int drm_fb_helper_parse_command_line(struct drm_fb_helper *fb_helper)
return 0;
}

+static void drm_fb_helper_save_lut_atomic(struct drm_crtc *crtc, struct drm_fb_helper *helper)
+{
+ int size;
+ uint16_t *r_base, *g_base, *b_base;
+ int i;
+
+ size = crtc->gamma_size * (sizeof(uint16_t));
+ r_base = crtc->gamma_store;
+ g_base = r_base + size;
+ b_base = g_base + size;
+
+ for (i = 0; i < crtc->gamma_size; i++)
+ helper->funcs->gamma_get(crtc, &r_base[i], &g_base[i], &b_base[i], i);
+}
+
+static void drm_fb_helper_restore_lut_atomic(struct drm_crtc *crtc)
+{
+ int size;
+ uint16_t *r_base, *g_base, *b_base;
+
+ size = crtc->gamma_size * (sizeof(uint16_t));
+ r_base = crtc->gamma_store;
+ g_base = r_base + size;
+ b_base = g_base + size;
+
+ crtc->funcs->gamma_set(crtc, r_base, g_base, b_base, 0, size);
+}
+
int drm_fb_helper_debug_enter(struct fb_info *info)
{
struct drm_fb_helper *helper = info->par;
@@ -260,6 +288,8 @@ int drm_fb_helper_debug_enter(struct fb_info *info)
continue;

funcs = mode_set->crtc->helper_private;
+
+ drm_fb_helper_save_lut_atomic(mode_set->crtc, helper);
funcs->mode_set_base_atomic(mode_set->crtc,
mode_set->fb,
mode_set->x,
@@ -309,6 +339,7 @@ int drm_fb_helper_debug_leave(struct fb_info *info)
continue;
}

+ drm_fb_helper_restore_lut_atomic(mode_set->crtc);
funcs->mode_set_base_atomic(mode_set->crtc, fb, crtc->x,
crtc->y, LEAVE_ATOMIC_MODE_SET);
}
--
1.6.3.3