Hi Thomas,

I love your patch! Yet something to improve:

[auto build test ERROR on next-20200305]
[also build test ERROR on v5.6-rc4]
[cannot apply to rockchip/for-next shawnguo/for-next sunxi/sunxi/for-next tegra/for-next linus/master v5.6-rc4 v5.6-rc3 v5.6-rc2]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Thomas-Zimmermann/drm-Convert-drivers-to-drm_simple_encoder_init/20200306-045931
base:    47466dcf84ee66a973ea7d2fca7e582fe9328932
config: mips-randconfig-a001-20200306 (attached as .config)
compiler: mipsel-linux-gcc (GCC) 5.5.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=5.5.0 make.cross ARCH=mips 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

All errors (new ones prefixed by >>):

   drivers/gpu/drm/arc/arcpgu_hdmi.c: In function 'arcpgu_drm_hdmi_init':
>> drivers/gpu/drm/arc/arcpgu_hdmi.c:34:8: error: implicit declaration of function 'drm_simple_encoder_init' [-Werror=implicit-function-declaration]
     ret = drm_simple_encoder_init(drm, encoder, DRM_MODE_ENCODER_TMDS);
           ^
   cc1: some warnings being treated as errors
--
   drivers/gpu/drm/arc/arcpgu_sim.c: In function 'arcpgu_drm_sim_init':
>> drivers/gpu/drm/arc/arcpgu_sim.c:68:8: error: implicit declaration of function 'drm_simple_encoder_init' [-Werror=implicit-function-declaration]
     ret = drm_simple_encoder_init(drm, encoder, DRM_MODE_ENCODER_VIRTUAL);
           ^
   cc1: some warnings being treated as errors

vim +/drm_simple_encoder_init +34 drivers/gpu/drm/arc/arcpgu_hdmi.c

    15	
    16	int arcpgu_drm_hdmi_init(struct drm_device *drm, struct device_node *np)
    17	{
    18		struct drm_encoder *encoder;
    19		struct drm_bridge *bridge;
    20	
    21		int ret = 0;
    22	
    23		encoder = devm_kzalloc(drm->dev, sizeof(*encoder), GFP_KERNEL);
    24		if (encoder == NULL)
    25			return -ENOMEM;
    26	
    27		/* Locate drm bridge from the hdmi encoder DT node */
    28		bridge = of_drm_find_bridge(np);
    29		if (!bridge)
    30			return -EPROBE_DEFER;
    31	
    32		encoder->possible_crtcs = 1;
    33		encoder->possible_clones = 0;
  > 34		ret = drm_simple_encoder_init(drm, encoder, DRM_MODE_ENCODER_TMDS);

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org