[PATCH v2] drm: fb-helper: Reject all pixel format changing requests

From: Eugeniy Paltsev
Date: Wed Oct 03 2018 - 12:46:17 EST


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

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@xxxxxxxxxxxx>
---
Changes v1->v2:
* Reject all pixel format changing request, not just the invalid ones.

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

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 16ec93b75dbf..48598d7f673f 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1580,6 +1580,25 @@ int drm_fb_helper_ioctl(struct fb_info *info, unsigned int cmd,
}
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
@@ -1590,7 +1609,6 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
{
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;
@@ -1610,72 +1628,15 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
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);
--
2.14.4