[Freedreno] [bug report] drm/msm/a6xx: Send ACD state to QMP at GMU resume

[Dan Carpenter]

Hello Konrad Dybcio,

The patch 88a0997f2f94: "drm/msm/a6xx: Send ACD state to QMP at GMU
resume" from Sep 25, 2023 (linux-next), leads to the following Smatch
static checker warning:

	drivers/gpu/drm/msm/adreno/a6xx_gmu.c:1813 a6xx_gmu_init()
	warn: ignoring unreachable code.

drivers/gpu/drm/msm/adreno/a6xx_gmu.c
    1774         gmu->cxpd = dev_pm_domain_attach_by_name(gmu->dev, "cx");
    1775         if (IS_ERR(gmu->cxpd)) {
    1776                 ret = PTR_ERR(gmu->cxpd);
    1777                 goto err_mmio;
    1778         }
    1779 
    1780         if (!device_link_add(gmu->dev, gmu->cxpd,
    1781                                         DL_FLAG_PM_RUNTIME)) {
    1782                 ret = -ENODEV;
    1783                 goto detach_cxpd;
    1784         }
    1785 
    1786         gmu->qmp = qmp_get(gmu->dev);
    1787         if (IS_ERR(gmu->qmp) && adreno_is_a7xx(adreno_gpu))
    1788                 return PTR_ERR(gmu->qmp);

This should be a goto something_undo_device_link_add;

    1789 
    1790         init_completion(&gmu->pd_gate);
    1791         complete_all(&gmu->pd_gate);
    1792         gmu->pd_nb.notifier_call = cxpd_notifier_cb;
    1793 
    1794         /*
    1795          * Get a link to the GX power domain to reset the GPU in case of GMU
    1796          * crash
    1797          */
    1798         gmu->gxpd = dev_pm_domain_attach_by_name(gmu->dev, "gx");
    1799 
    1800         /* Get the power levels for the GMU and GPU */
    1801         a6xx_gmu_pwrlevels_probe(gmu);
    1802 
    1803         /* Set up the HFI queues */
    1804         a6xx_hfi_init(gmu);
    1805 
    1806         /* Initialize RPMh */
    1807         a6xx_gmu_rpmh_init(gmu);
    1808 
    1809         gmu->initialized = true;
    1810 
    1811         return 0;
    1812 
--> 1813         if (!IS_ERR_OR_NULL(gmu->qmp))
    1814                 qmp_put(gmu->qmp);

Unreachable.  But we don't need to undo the qmp_get() in this funciton
because that's the last failure path.  Do we need to add a qmp_put() to
a6xx_gmu_remove()?  At first glance that looks like the undo function
for a6xx_gmu_init().

    1815 
    1816 detach_cxpd:
    1817         dev_pm_domain_detach(gmu->cxpd, false);
    1818 
    1819 err_mmio:
    1820         iounmap(gmu->mmio);
    1821         if (platform_get_resource_byname(pdev, IORESOURCE_MEM, "rscc"))
    1822                 iounmap(gmu->rscc);
    1823         free_irq(gmu->gmu_irq, gmu);
    1824         free_irq(gmu->hfi_irq, gmu);
    1825 
    1826 err_memory:
    1827         a6xx_gmu_memory_free(gmu);
    1828 err_put_device:
    1829         /* Drop reference taken in of_find_device_by_node */
    1830         put_device(gmu->dev);
    1831 
    1832         return ret;
    1833 }

regards,
dan carpenter