[PATCH v2 5/9] drm/msm: add headless gpu device (for imx5)

[Jonathan Marek <jonathan@marek.ca>]

This patch allows using drm/msm without qcom display hardware. This is
especially useful for iMX5 hardware, which has a a2xx GPU but uses the
imx-drm driver for display.

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
---
v2: added commit message and removed unnecessary comment

 drivers/gpu/drm/msm/Kconfig       |  4 ++--
 drivers/gpu/drm/msm/msm_debugfs.c |  2 +-
 drivers/gpu/drm/msm/msm_drv.c     | 21 +++++++++++----------
 3 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/msm/Kconfig b/drivers/gpu/drm/msm/Kconfig
index 843a9d40c05e..cf549f1ed403 100644
--- a/drivers/gpu/drm/msm/Kconfig
+++ b/drivers/gpu/drm/msm/Kconfig
@@ -2,7 +2,7 @@
 config DRM_MSM
 	tristate "MSM DRM"
 	depends on DRM
-	depends on ARCH_QCOM || (ARM && COMPILE_TEST)
+	depends on ARCH_QCOM || SOC_IMX5 || (ARM && COMPILE_TEST)
 	depends on OF && COMMON_CLK
 	depends on MMU
 	select QCOM_MDT_LOADER if ARCH_QCOM
@@ -11,7 +11,7 @@ config DRM_MSM
 	select DRM_PANEL
 	select SHMEM
 	select TMPFS
-	select QCOM_SCM
+	select QCOM_SCM if ARCH_QCOM
 	select WANT_DEV_COREDUMP
 	select SND_SOC_HDMI_CODEC if SND_SOC
 	select SYNC_FILE
diff --git a/drivers/gpu/drm/msm/msm_debugfs.c b/drivers/gpu/drm/msm/msm_debugfs.c
index f0da0d3c8a80..1ca99ca356a4 100644
--- a/drivers/gpu/drm/msm/msm_debugfs.c
+++ b/drivers/gpu/drm/msm/msm_debugfs.c
@@ -235,7 +235,7 @@ int msm_debugfs_init(struct drm_minor *minor)
 	debugfs_create_file("gpu", S_IRUSR, minor->debugfs_root,
 		dev, &msm_gpu_fops);
 
-	if (priv->kms->funcs->debugfs_init) {
+	if (priv->kms && priv->kms->funcs->debugfs_init) {
 		ret = priv->kms->funcs->debugfs_init(priv->kms, minor);
 		if (ret)
 			return ret;
diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index 9f219e02f3c7..3f35e57202ef 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -344,6 +344,7 @@ static int msm_drm_uninit(struct device *dev)
 	return 0;
 }
 
+#define KMS_HEADLESS 1
 #define KMS_MDP4 4
 #define KMS_MDP5 5
 #define KMS_DPU  3
@@ -495,6 +496,9 @@ static int msm_drm_init(struct device *dev, struct drm_driver *drv)
 	msm_gem_shrinker_init(ddev);
 
 	switch (get_mdp_ver(pdev)) {
+	case KMS_HEADLESS:
+		priv->kms = kms = NULL;
+		break;
 	case KMS_MDP4:
 		kms = mdp4_kms_init(ddev);
 		priv->kms = kms;
@@ -512,12 +516,6 @@ static int msm_drm_init(struct device *dev, struct drm_driver *drv)
 	}
 
 	if (IS_ERR(kms)) {
-		/*
-		 * NOTE: once we have GPU support, having no kms should not
-		 * be considered fatal.. ideally we would still support gpu
-		 * and (for example) use dmabuf/prime to share buffers with
-		 * imx drm driver on iMX5
-		 */
 		dev_err(dev, "failed to load kms\n");
 		ret = PTR_ERR(kms);
 		goto err_msm_uninit;
@@ -633,7 +631,7 @@ static int msm_drm_init(struct device *dev, struct drm_driver *drv)
 	drm_mode_config_reset(ddev);
 
 #ifdef CONFIG_DRM_FBDEV_EMULATION
-	if (fbdev)
+	if (kms && fbdev)
 		priv->fbdev = msm_fbdev_init(ddev);
 #endif
 
@@ -1315,9 +1313,11 @@ static int msm_pdev_probe(struct platform_device *pdev)
 	struct component_match *match = NULL;
 	int ret;
 
-	ret = add_display_components(&pdev->dev, &match);
-	if (ret)
-		return ret;
+	if (get_mdp_ver(pdev) != KMS_HEADLESS) {
+		ret = add_display_components(&pdev->dev, &match);
+		if (ret)
+			return ret;
+	}
 
 	ret = add_gpu_components(&pdev->dev, &match);
 	if (ret)
@@ -1342,6 +1342,7 @@ static int msm_pdev_remove(struct platform_device *pdev)
 }
 
 static const struct of_device_id dt_match[] = {
+	{ .compatible = "qcom,adreno-headless", .data = (void *)KMS_HEADLESS },
 	{ .compatible = "qcom,mdp4", .data = (void *)KMS_MDP4 },
 	{ .compatible = "qcom,mdss", .data = (void *)KMS_MDP5 },
 	{ .compatible = "qcom,sdm845-mdss", .data = (void *)KMS_DPU },
-- 
2.17.1