Re: [PATCH 1/7] drm/mediatek: move dpi private data to device

From: kbuild test robot
Date: Tue May 08 2018 - 13:20:11 EST

Hi chunhui,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on drm/drm-next]
[also build test WARNING on v4.17-rc4 next-20180507]
[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/Bibby-Hsieh/drm-mediatek-support-hdmi-output-for-mt2701-and-mt7623/20180508-140924
base: git://people.freedesktop.org/~airlied/linux.git drm-next
config: arm-allyesconfig (attached as .config)
compiler: arm-linux-gnueabi-gcc (Debian 7.2.0-11) 7.2.0
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
make.cross ARCH=arm

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/mediatek/mtk_dpi.c: In function 'mtk_dpi_power_on':
>> drivers/gpu//drm/mediatek/mtk_dpi.c:444:9: warning: 'ret' may be used uninitialized in this function [-Wmaybe-uninitialized]
return ret;
^~~

vim +/ret +444 drivers/gpu//drm/mediatek/mtk_dpi.c

9e629c17 Jie Qiu 2016-01-04 405
9e629c17 Jie Qiu 2016-01-04 406 static int mtk_dpi_power_on(struct mtk_dpi *dpi, enum mtk_dpi_power_ctl pctl)
9e629c17 Jie Qiu 2016-01-04 407 {
9e629c17 Jie Qiu 2016-01-04 408 int ret;
9e629c17 Jie Qiu 2016-01-04 409
51df75e5 chunhui dai 2018-05-08 410 if (++dpi->refcount != 1)
51df75e5 chunhui dai 2018-05-08 411 return 0;
51df75e5 chunhui dai 2018-05-08 412
9e629c17 Jie Qiu 2016-01-04 413 dpi->power_ctl |= pctl;
9e629c17 Jie Qiu 2016-01-04 414
9e629c17 Jie Qiu 2016-01-04 415 if (!(dpi->power_ctl & DPI_POWER_START) &&
9e629c17 Jie Qiu 2016-01-04 416 !(dpi->power_ctl & DPI_POWER_ENABLE))
51df75e5 chunhui dai 2018-05-08 417 goto err_refcount;
9e629c17 Jie Qiu 2016-01-04 418
9e629c17 Jie Qiu 2016-01-04 419 if (dpi->power_sta)
51df75e5 chunhui dai 2018-05-08 420 goto err_refcount;
9e629c17 Jie Qiu 2016-01-04 421
9e629c17 Jie Qiu 2016-01-04 422 ret = clk_prepare_enable(dpi->engine_clk);
9e629c17 Jie Qiu 2016-01-04 423 if (ret) {
9e629c17 Jie Qiu 2016-01-04 424 dev_err(dpi->dev, "Failed to enable engine clock: %d\n", ret);
9e629c17 Jie Qiu 2016-01-04 425 goto err_eng;
9e629c17 Jie Qiu 2016-01-04 426 }
9e629c17 Jie Qiu 2016-01-04 427
9e629c17 Jie Qiu 2016-01-04 428 ret = clk_prepare_enable(dpi->pixel_clk);
9e629c17 Jie Qiu 2016-01-04 429 if (ret) {
9e629c17 Jie Qiu 2016-01-04 430 dev_err(dpi->dev, "Failed to enable pixel clock: %d\n", ret);
9e629c17 Jie Qiu 2016-01-04 431 goto err_pixel;
9e629c17 Jie Qiu 2016-01-04 432 }
9e629c17 Jie Qiu 2016-01-04 433
9e629c17 Jie Qiu 2016-01-04 434 mtk_dpi_enable(dpi);
9e629c17 Jie Qiu 2016-01-04 435 dpi->power_sta = true;
9e629c17 Jie Qiu 2016-01-04 436 return 0;
9e629c17 Jie Qiu 2016-01-04 437
9e629c17 Jie Qiu 2016-01-04 438 err_pixel:
9e629c17 Jie Qiu 2016-01-04 439 clk_disable_unprepare(dpi->engine_clk);
9e629c17 Jie Qiu 2016-01-04 440 err_eng:
9e629c17 Jie Qiu 2016-01-04 441 dpi->power_ctl &= ~pctl;
51df75e5 chunhui dai 2018-05-08 442 err_refcount:
51df75e5 chunhui dai 2018-05-08 443 dpi->refcount--;
9e629c17 Jie Qiu 2016-01-04 @444 return ret;
9e629c17 Jie Qiu 2016-01-04 445 }
9e629c17 Jie Qiu 2016-01-04 446

:::::: The code at line 444 was first introduced by commit
:::::: 9e629c17aa8d7a75b8c1d99ed42892cd8ba7cdc4 drm/mediatek: Add DPI sub driver

:::::: TO: Jie Qiu <jie.qiu@xxxxxxxxxxxx>
:::::: CC: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>

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