Re: [PATCH] drm/bridge/sii8620: fix display modes validation

From: kbuild test robot
Date: Thu Jan 25 2018 - 18:28:33 EST


Hi Maciej,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on drm/drm-next]
[also build test WARNING on next-20180119]
[cannot apply to v4.15-rc9]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/Maciej-Purski/drm-bridge-sii8620-fix-display-modes-validation/20180125-174703
base: git://people.freedesktop.org/~airlied/linux.git drm-next
config: i386-randconfig-sb0-01260635 (attached as .config)
compiler: gcc-4.9 (Debian 4.9.4-2) 4.9.4
reproduce:
# save the attached .config to linux build tree
make ARCH=i386

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

drivers/gpu/drm/bridge/sil-sii8620.c: In function 'sii8620_mode_valid':
>> drivers/gpu/drm/bridge/sil-sii8620.c:2242:2: warning: 'ret' may be used uninitialized in this function [-Wmaybe-uninitialized]
return ret;
^

vim +/ret +2242 drivers/gpu/drm/bridge/sil-sii8620.c

2220
2221 static enum drm_mode_status sii8620_mode_valid(struct drm_bridge *bridge,
2222 const struct drm_display_mode *mode)
2223 {
2224 enum drm_mode_status ret;
2225 struct sii8620 *ctx = bridge_to_sii8620(bridge);
2226 int pack_required = sii8620_is_packing_required(ctx, mode);
2227 bool can_pack = ctx->devcap[MHL_DCAP_VID_LINK_MODE] &
2228 MHL_DCAP_VID_LINK_PPIXEL;
2229
2230 switch (pack_required) {
2231 case -1:
2232 ret = MODE_CLOCK_HIGH;
2233 break;
2234 case 1:
2235 ret = (can_pack) ? MODE_OK : MODE_CLOCK_HIGH;
2236 break;
2237 case 0:
2238 ret = MODE_OK;
2239 break;
2240 }
2241
> 2242 return ret;
2243 }
2244

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