[PATCH 4.18 12/34] drm: fb-helper: Reject all pixel format changing requests

Greg Kroah-Hartman
2018-11-08T22:09:26Z

From: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>

commit db05c481977599236f12a85e55de9f5ab37b0a2c upstream.

drm fbdev emulation doesn't support changing the pixel format at all,
so reject all pixel format changing requests.

Cc: stable@vger.kernel.org
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20181003164538.5534-1-Eugeniy.Paltsev@synopsys.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/drm_fb_helper.c | 91 +++++++++++-----------------------------
1 file changed, 26 insertions(+), 65 deletions(-)

--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1561,6 +1561,25 @@ unlock:
}
EXPORT_SYMBOL(drm_fb_helper_ioctl);

+static bool drm_fb_pixel_format_equal(const struct fb_var_screeninfo *var_1,
+ const struct fb_var_screeninfo *var_2)
+{
+ return var_1->bits_per_pixel == var_2->bits_per_pixel &&
+ var_1->grayscale == var_2->grayscale &&
+ var_1->red.offset == var_2->red.offset &&
+ var_1->red.length == var_2->red.length &&
+ var_1->red.msb_right == var_2->red.msb_right &&
+ var_1->green.offset == var_2->green.offset &&
+ var_1->green.length == var_2->green.length &&
+ var_1->green.msb_right == var_2->green.msb_right &&
+ var_1->blue.offset == var_2->blue.offset &&
+ var_1->blue.length == var_2->blue.length &&
+ var_1->blue.msb_right == var_2->blue.msb_right &&
+ var_1->transp.offset == var_2->transp.offset &&
+ var_1->transp.length == var_2->transp.length &&
+ var_1->transp.msb_right == var_2->transp.msb_right;
+}
+
/**
* drm_fb_helper_check_var - implementation for &fb_ops.fb_check_var
* @var: screeninfo to check
@@ -1571,7 +1590,6 @@ int drm_fb_helper_check_var(struct fb_va
{
struct drm_fb_helper *fb_helper = info->par;
struct drm_framebuffer *fb = fb_helper->fb;
- int depth;

if (var->pixclock != 0 || in_dbg_master())
return -EINVAL;
@@ -1591,72 +1609,15 @@ int drm_fb_helper_check_var(struct fb_va
return -EINVAL;
}

- switch (var->bits_per_pixel) {
- case 16:
- depth = (var->green.length == 6) ? 16 : 15;
- break;
- case 32:
- depth = (var->transp.length > 0) ? 32 : 24;
- break;
- default:
- depth = var->bits_per_pixel;
- break;
- }
-
- switch (depth) {
- case 8:
- var->red.offset = 0;
- var->green.offset = 0;
- var->blue.offset = 0;
- var->red.length = 8;
- var->green.length = 8;
- var->blue.length = 8;
- var->transp.length = 0;
- var->transp.offset = 0;
- break;
- case 15:
- var->red.offset = 10;
- var->green.offset = 5;
- var->blue.offset = 0;
- var->red.length = 5;
- var->green.length = 5;
- var->blue.length = 5;
- var->transp.length = 1;
- var->transp.offset = 15;
- break;
- case 16:
- var->red.offset = 11;
- var->green.offset = 5;
- var->blue.offset = 0;
- var->red.length = 5;
- var->green.length = 6;
- var->blue.length = 5;
- var->transp.length = 0;
- var->transp.offset = 0;
- break;
- case 24:
- var->red.offset = 16;
- var->green.offset = 8;
- var->blue.offset = 0;
- var->red.length = 8;
- var->green.length = 8;
- var->blue.length = 8;
- var->transp.length = 0;
- var->transp.offset = 0;
- break;
- case 32:
- var->red.offset = 16;
- var->green.offset = 8;
- var->blue.offset = 0;
- var->red.length = 8;
- var->green.length = 8;
- var->blue.length = 8;
- var->transp.length = 8;
- var->transp.offset = 24;
- break;
- default:
+ /*
+ * drm fbdev emulation doesn't support changing the pixel format at all,
+ * so reject all pixel format changing requests.
+ */
+ if (!drm_fb_pixel_format_equal(var, &info->var)) {
+ DRM_DEBUG("fbdev emulation doesn't support changing the pixel format\n");
return -EINVAL;
}
+
return 0;
}
EXPORT_SYMBOL(drm_fb_helper_check_var);