drivers/gpu/drm/drm_mipi_dbi.c:262:52: warning: Either the condition '!fb' is redundant or there is possible null pointer dereference: fb.

From: kernel test robot
Date: Thu Feb 18 2021 - 08:10:58 EST

tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: f40ddce88593482919761f74910f42f4b84c004b
commit: 7e06886bbfca73717e45a0f20cdb4053793c191b drm/mipi-dbi: Remove ->enabled
date: 8 months ago
compiler: riscv64-linux-gcc (GCC) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>


cppcheck possible warnings: (new ones prefixed by >>, may not real problems)

>> drivers/gpu/drm/drm_mipi_dbi.c:262:52: warning: Either the condition '!fb' is redundant or there is possible null pointer dereference: fb. [nullPointerRedundantCheck]
struct mipi_dbi_dev *dbidev = drm_to_mipi_dbi_dev(fb->dev);
^
drivers/gpu/drm/drm_mipi_dbi.c:271:14: note: Assuming that condition '!fb' is not redundant
if (WARN_ON(!fb))
^
drivers/gpu/drm/drm_mipi_dbi.c:262:52: note: Null pointer dereference
struct mipi_dbi_dev *dbidev = drm_to_mipi_dbi_dev(fb->dev);
^

vim +262 drivers/gpu/drm/drm_mipi_dbi.c

f41a8a69890d08 drivers/gpu/drm/drm_mipi_dbi.c Geert Uytterhoeven 2020-01-15 257
af74138160e194 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-01-15 258 static void mipi_dbi_fb_dirty(struct drm_framebuffer *fb, struct drm_rect *rect)
02dd95fe316936 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2017-01-22 259 {
7c9f1312cfca15 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-07-22 260 struct drm_gem_object *gem = drm_gem_fb_get_obj(fb, 0);
7c9f1312cfca15 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-07-22 261 struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(gem);
84137b866e834a drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-07-22 @262 struct mipi_dbi_dev *dbidev = drm_to_mipi_dbi_dev(fb->dev);
af74138160e194 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-01-15 263 unsigned int height = rect->y2 - rect->y1;
af74138160e194 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-01-15 264 unsigned int width = rect->x2 - rect->x1;
84137b866e834a drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-07-22 265 struct mipi_dbi *dbi = &dbidev->dbi;
36b5057216236a drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-07-22 266 bool swap = dbi->swap_bytes;
9d5645ad1b979c drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-02-25 267 int idx, ret = 0;
02dd95fe316936 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2017-01-22 268 bool full;
02dd95fe316936 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2017-01-22 269 void *tr;
02dd95fe316936 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2017-01-22 270
7e06886bbfca73 drivers/gpu/drm/drm_mipi_dbi.c Daniel Vetter 2020-06-12 271 if (WARN_ON(!fb))
af74138160e194 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-01-15 272 return;
02dd95fe316936 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2017-01-22 273
9d5645ad1b979c drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-02-25 274 if (!drm_dev_enter(fb->dev, &idx))
9d5645ad1b979c drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-02-25 275 return;
9d5645ad1b979c drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-02-25 276
af74138160e194 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-01-15 277 full = width == fb->width && height == fb->height;
02dd95fe316936 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2017-01-22 278
b051b3459bbae9 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-01-15 279 DRM_DEBUG_KMS("Flushing [FB:%d] " DRM_RECT_FMT "\n", fb->base.id, DRM_RECT_ARG(rect));
02dd95fe316936 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2017-01-22 280
36b5057216236a drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-07-22 281 if (!dbi->dc || !full || swap ||
02dd95fe316936 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2017-01-22 282 fb->format->format == DRM_FORMAT_XRGB8888) {
440961d20959e8 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-07-22 283 tr = dbidev->tx_buf;
440961d20959e8 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-07-22 284 ret = mipi_dbi_buf_copy(dbidev->tx_buf, fb, rect, swap);
02dd95fe316936 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2017-01-22 285 if (ret)
af74138160e194 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-01-15 286 goto err_msg;
02dd95fe316936 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2017-01-22 287 } else {
02dd95fe316936 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2017-01-22 288 tr = cma_obj->vaddr;
02dd95fe316936 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2017-01-22 289 }
02dd95fe316936 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2017-01-22 290
f41a8a69890d08 drivers/gpu/drm/drm_mipi_dbi.c Geert Uytterhoeven 2020-01-15 291 mipi_dbi_set_window_address(dbidev, rect->x1, rect->x2 - 1, rect->y1,
f41a8a69890d08 drivers/gpu/drm/drm_mipi_dbi.c Geert Uytterhoeven 2020-01-15 292 rect->y2 - 1);
02dd95fe316936 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2017-01-22 293
36b5057216236a drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-07-22 294 ret = mipi_dbi_command_buf(dbi, MIPI_DCS_WRITE_MEMORY_START, tr,
af74138160e194 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-01-15 295 width * height * 2);
af74138160e194 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-01-15 296 err_msg:
af74138160e194 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-01-15 297 if (ret)
af74138160e194 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-01-15 298 dev_err_once(fb->dev->dev, "Failed to update display %d\n", ret);
9d5645ad1b979c drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-02-25 299
9d5645ad1b979c drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2019-02-25 300 drm_dev_exit(idx);
02dd95fe316936 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2017-01-22 301 }
02dd95fe316936 drivers/gpu/drm/tinydrm/mipi-dbi.c Noralf Trønnes 2017-01-22 302

:::::: The code at line 262 was first introduced by commit
:::::: 84137b866e834ac937582b04ae9bed0a72356a6a drm/tinydrm: Split struct mipi_dbi in two

:::::: TO: Noralf Trønnes <noralf@xxxxxxxxxxx>
:::::: CC: Noralf Trønnes <noralf@xxxxxxxxxxx>

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