On Sat, Jun 30, 2018 at 10:12:21PM +0300, Dan Carpenter wrote:
Hi Ville,
Thank you for the patch! Perhaps something to improve:
url: https://github.com/0day-ci/linux/commits/Ville-Syrjala/drm-Third-attempt-at-... base: git://people.freedesktop.org/~airlied/linux.git drm-next
smatch warnings: drivers/gpu/drm/nouveau/nouveau_connector.c:461 nouveau_connector_ddc_detect() error: uninitialized symbol 'nv_encoder'.
# https://github.com/0day-ci/linux/commit/7ec8bb65386edfb0b2bdc8e8391eb5e6eac4... git remote add linux-review https://github.com/0day-ci/linux git remote update linux-review git checkout 7ec8bb65386edfb0b2bdc8e8391eb5e6eac44c06 vim +/nv_encoder +461 drivers/gpu/drm/nouveau/nouveau_connector.c
6ee738610 Ben Skeggs 2009-12-11 407 8777c5c11 Ben Skeggs 2014-06-06 408 static struct nouveau_encoder * 8777c5c11 Ben Skeggs 2014-06-06 409 nouveau_connector_ddc_detect(struct drm_connector *connector) 6ee738610 Ben Skeggs 2009-12-11 410 { 6ee738610 Ben Skeggs 2009-12-11 411 struct drm_device *dev = connector->dev; 1a1841d30 Ben Skeggs 2012-12-10 412 struct nouveau_connector *nv_connector = nouveau_connector(connector); 77145f1cb Ben Skeggs 2012-07-31 413 struct nouveau_drm *drm = nouveau_drm(dev); 1167c6bc5 Ben Skeggs 2016-05-18 414 struct nvkm_gpio *gpio = nvxx_gpio(&drm->client.device); 8777c5c11 Ben Skeggs 2014-06-06 415 struct nouveau_encoder *nv_encoder; 6d385c0aa Rob Clark 2014-07-17 416 struct drm_encoder *encoder; 1a1841d30 Ben Skeggs 2012-12-10 417 int i, panel = -ENODEV; 1a1841d30 Ben Skeggs 2012-12-10 418 1a1841d30 Ben Skeggs 2012-12-10 419 /* eDP panels need powering on by us (if the VBIOS doesn't default it 1a1841d30 Ben Skeggs 2012-12-10 420 * to on) before doing any AUX channel transactions. LVDS panel power 1a1841d30 Ben Skeggs 2012-12-10 421 * is handled by the SOR itself, and not required for LVDS DDC. 1a1841d30 Ben Skeggs 2012-12-10 422 */ 1a1841d30 Ben Skeggs 2012-12-10 423 if (nv_connector->type == DCB_CONNECTOR_eDP) { 2ea7249fe Ben Skeggs 2015-08-20 424 panel = nvkm_gpio_get(gpio, 0, DCB_GPIO_PANEL_POWER, 0xff); 1a1841d30 Ben Skeggs 2012-12-10 425 if (panel == 0) { 2ea7249fe Ben Skeggs 2015-08-20 426 nvkm_gpio_set(gpio, 0, DCB_GPIO_PANEL_POWER, 0xff, 1); 1a1841d30 Ben Skeggs 2012-12-10 427 msleep(300); 1a1841d30 Ben Skeggs 2012-12-10 428 } 1a1841d30 Ben Skeggs 2012-12-10 429 } 6ee738610 Ben Skeggs 2009-12-11 430 7ec8bb653 Ville Syrjälä 2018-06-28 431 drm_connector_for_each_possible_encoder(connector, encoder, i) { 6d385c0aa Rob Clark 2014-07-17 432 nv_encoder = nouveau_encoder(encoder); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ If we enter the loop that means nv_encoder is non-NULL. Smatch can't prove that we always enter the loop in this case for whatever reason but my guess is that we always do.
4ca2b7120 Francisco Jerez 2010-08-08 433 8777c5c11 Ben Skeggs 2014-06-06 434 if (nv_encoder->dcb->type == DCB_OUTPUT_DP) { 8777c5c11 Ben Skeggs 2014-06-06 435 int ret = nouveau_dp_detect(nv_encoder); 52aa30f25 Ben Skeggs 2016-11-04 436 if (ret == NOUVEAU_DP_MST) 52aa30f25 Ben Skeggs 2016-11-04 437 return NULL; 52aa30f25 Ben Skeggs 2016-11-04 438 if (ret == NOUVEAU_DP_SST) 8777c5c11 Ben Skeggs 2014-06-06 439 break; 8777c5c11 Ben Skeggs 2014-06-06 440 } else 39c1c9011 Lukas Wunner 2016-01-11 441 if ((vga_switcheroo_handler_flags() & 39c1c9011 Lukas Wunner 2016-01-11 442 VGA_SWITCHEROO_CAN_SWITCH_DDC) && 39c1c9011 Lukas Wunner 2016-01-11 443 nv_encoder->dcb->type == DCB_OUTPUT_LVDS && 39c1c9011 Lukas Wunner 2016-01-11 444 nv_encoder->i2c) { 39c1c9011 Lukas Wunner 2016-01-11 445 int ret; 39c1c9011 Lukas Wunner 2016-01-11 446 vga_switcheroo_lock_ddc(dev->pdev); 39c1c9011 Lukas Wunner 2016-01-11 447 ret = nvkm_probe_i2c(nv_encoder->i2c, 0x50); 39c1c9011 Lukas Wunner 2016-01-11 448 vga_switcheroo_unlock_ddc(dev->pdev); 39c1c9011 Lukas Wunner 2016-01-11 449 if (ret) 39c1c9011 Lukas Wunner 2016-01-11 450 break; 39c1c9011 Lukas Wunner 2016-01-11 451 } else 8777c5c11 Ben Skeggs 2014-06-06 452 if (nv_encoder->i2c) { 2aa5eac51 Ben Skeggs 2015-08-20 453 if (nvkm_probe_i2c(nv_encoder->i2c, 0x50)) 1a1841d30 Ben Skeggs 2012-12-10 454 break; 6ee738610 Ben Skeggs 2009-12-11 455 } 6ee738610 Ben Skeggs 2009-12-11 456 } 6ee738610 Ben Skeggs 2009-12-11 457 1a1841d30 Ben Skeggs 2012-12-10 458 /* eDP panel not detected, restore panel power GPIO to previous 1a1841d30 Ben Skeggs 2012-12-10 459 * state to avoid confusing the SOR for other output types. 1a1841d30 Ben Skeggs 2012-12-10 460 */ 8777c5c11 Ben Skeggs 2014-06-06 @461 if (!nv_encoder && panel == 0) ^^^^^^^^^^^ So testing for NULL doesn't make sense. It's either non-NULL if we entered the loop at least once or it's uninitialized if we didn't enter the loop.
Yeah, seems like a bogus check. I suppose in theory you could have a connector with no encoders, although I can't think of any good reason why anyone would do that.
2ea7249fe Ben Skeggs 2015-08-20 462 nvkm_gpio_set(gpio, 0, DCB_GPIO_PANEL_POWER, 0xff, panel); 1a1841d30 Ben Skeggs 2012-12-10 463 8777c5c11 Ben Skeggs 2014-06-06 464 return nv_encoder; 6ee738610 Ben Skeggs 2009-12-11 465 } 6ee738610 Ben Skeggs 2009-12-11 466
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