[PATCH v2 3/5] drm/msm: add a kernel param to select between MDP5 and DPU drivers

[Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>]

For some of the platforms (e.g. SDM660, SDM630, MSM8996, etc.) it is
possible to support this platform via the DPU driver (e.g. to provide
support for DP, multirect, etc). Add a modparam to be able to switch
between these two drivers.

All platforms supported by both drivers are by default handled by the
MDP5 driver. To let them be handled by the DPU driver pass the
`msm.prefer_mdp5=false` kernel param.

Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c  |  3 +++
 drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c |  3 +++
 drivers/gpu/drm/msm/msm_drv.c            | 31 ++++++++++++++++++++++++
 drivers/gpu/drm/msm/msm_drv.h            |  1 +
 4 files changed, 38 insertions(+)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
index 20ba03e9c936..c8d85a64e16c 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
@@ -1351,6 +1351,9 @@ static int dpu_kms_init(struct drm_device *ddev)
 
 static int dpu_dev_probe(struct platform_device *pdev)
 {
+	if (!msm_disp_drv_should_bind(&pdev->dev, true))
+		return -ENODEV;
+
 	return msm_drv_probe(&pdev->dev, dpu_kms_init);
 }
 
diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
index 8a7b44376bc6..b37ebb068dce 100644
--- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
+++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
@@ -935,6 +935,9 @@ static int mdp5_dev_probe(struct platform_device *pdev)
 
 	DBG("");
 
+	if (!msm_disp_drv_should_bind(&pdev->dev, false))
+		return -ENODEV;
+
 	ret = mdp5_setup_interconnect(pdev);
 	if (ret)
 		return ret;
diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index 05fe32c3a4b4..3f6d884c90e0 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -1186,6 +1186,37 @@ static int add_components_mdp(struct device *master_dev,
 	return 0;
 }
 
+#if !IS_REACHABLE(CONFIG_DRM_MSM_MDP5) || !IS_REACHABLE(CONFIG_DRM_MSM_DPU)
+bool msm_disp_drv_should_bind(struct device *dev, bool mdp5_driver)
+{
+	/* If just a single driver is enabled, use it no matter what */
+	return true;
+}
+#else
+
+static bool prefer_mdp5 = true;
+MODULE_PARM_DESC(prefer_mdp5, "Select whether MDP5 or DPU driver should be preferred");
+module_param(prefer_mdp5, bool, 0444);
+
+/* list all platforms supported by both mdp5 and dpu drivers */
+static const char *const msm_mdp5_dpu_migration[] = {
+	NULL,
+};
+
+bool msm_disp_drv_should_bind(struct device *dev, bool dpu_driver)
+{
+	/* If it is not an MDP5 device, do not try MDP5 driver */
+	if (!of_device_is_compatible(dev->of_node, "qcom,mdp5"))
+		return dpu_driver;
+
+	/* If it is not in the migration list, use MDP5 */
+	if (!of_device_compatible_match(dev->of_node, msm_mdp5_dpu_migration))
+		return !dpu_driver;
+
+	return prefer_mdp5 ? !dpu_driver : dpu_driver;
+}
+#endif
+
 /*
  * We don't know what's the best binding to link the gpu with the drm device.
  * Fow now, we just hunt for all the possible gpus that we support, and add them
diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
index 6eeb3517c3e4..4fee19549cc8 100644
--- a/drivers/gpu/drm/msm/msm_drv.h
+++ b/drivers/gpu/drm/msm/msm_drv.h
@@ -571,5 +571,6 @@ int msm_drv_probe(struct device *dev,
 	int (*kms_init)(struct drm_device *dev));
 void msm_drv_shutdown(struct platform_device *pdev);
 
+bool msm_disp_drv_should_bind(struct device *dev, bool dpu_driver);
 
 #endif /* __MSM_DRV_H__ */
-- 
2.39.2