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

[Konrad Dybcio]

On 10/12/23 11:10, Dan Carpenter wrote:
> 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:
Thanks for the heads up, Dan!

Can you give my below solution a quick looksee and check if it looks right?

Konrad


 From 5b2dd0b74cc06f2d4af9aed95fa314001a2facf5 Mon Sep 17 00:00:00 2001
From: Konrad Dybcio <konrad.dybcio at linaro.org>
Date: Thu, 12 Oct 2023 18:29:28 +0200
Subject: [PATCH] drm/msm/a6xx: Fix up QMP handling

The commit referenced in the Fixes tag had a couple problems, (as
pointed out by Dan):

- qmp_put was never called, resulting in refcnt leaks
- failling to acquire the QMP mailbox on A7xx would not undo the probe
   function properly
- the qmp_put call present in the code was unreachable

Fix all of these issues.

Reported-by: Dan Carpenter <dan.carpenter at linaro.org>
Fixes: 88a0997f2f94 ("drm/msm/a6xx: Send ACD state to QMP at GMU resume")
Signed-off-by: Konrad Dybcio <konrad.dybcio at linaro.org>
---
  drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 18 ++++++++++++------
  1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c 
b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
index 0555a0134fad..8c4900444b2c 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
@@ -1558,6 +1558,9 @@ void a6xx_gmu_remove(struct a6xx_gpu *a6xx_gpu)
  		dev_pm_domain_detach(gmu->gxpd, false);
  	}

+	if (!IS_ERR_OR_NULL(gmu->qmp))
+		qmp_put(gmu->qmp);
+
  	iounmap(gmu->mmio);
  	if (platform_get_resource_byname(pdev, IORESOURCE_MEM, "rscc"))
  		iounmap(gmu->rscc);
@@ -1654,6 +1657,7 @@ int a6xx_gmu_init(struct a6xx_gpu *a6xx_gpu, 
struct device_node *node)
  	struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
  	struct a6xx_gmu *gmu = &a6xx_gpu->gmu;
  	struct platform_device *pdev = of_find_device_by_node(node);
+	struct device_link *link;
  	int ret;

  	if (!pdev)
@@ -1777,15 +1781,17 @@ int a6xx_gmu_init(struct a6xx_gpu *a6xx_gpu, 
struct device_node *node)
  		goto err_mmio;
  	}

-	if (!device_link_add(gmu->dev, gmu->cxpd,
-					DL_FLAG_PM_RUNTIME)) {
+	link = device_link_add(gmu->dev, gmu->cxpd, DL_FLAG_PM_RUNTIME);
+	if (!link) {
  		ret = -ENODEV;
  		goto detach_cxpd;
  	}

  	gmu->qmp = qmp_get(gmu->dev);
-	if (IS_ERR(gmu->qmp) && adreno_is_a7xx(adreno_gpu))
-		return PTR_ERR(gmu->qmp);
+	if (IS_ERR(gmu->qmp) && adreno_is_a7xx(adreno_gpu)) {
+		ret = PTR_ERR(gmu->qmp);
+		goto remove_device_link;
+	}

  	init_completion(&gmu->pd_gate);
  	complete_all(&gmu->pd_gate);
@@ -1810,8 +1816,8 @@ int a6xx_gmu_init(struct a6xx_gpu *a6xx_gpu, 
struct device_node *node)

  	return 0;

-	if (!IS_ERR_OR_NULL(gmu->qmp))
-		qmp_put(gmu->qmp);
+remove_device_link:
+	device_link_del(link);

  detach_cxpd:
  	dev_pm_domain_detach(gmu->cxpd, false);
-- 
2.39.2