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

[Jonathan marek <jonathan@xxxxxxxx>]

On 11/26/2018 10:48 AM, Jordan Crouse wrote:
> On Wed, Nov 21, 2018 at 08:52:31PM -0500, Jonathan Marek wrote:
> > 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@xxxxxxxx>
> > ---
> > 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
>
> This is good - there are probably a handful of others you can add too -
> WANT_DEV_COREDUMP for example (at least for now) but you can audit those later
> as you try to cut down your binary size.
>
> Also serves as an important reminder for the rest of us that Adreno just isn't
> for Snapdragon anymore.
>
> > 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 },
>
> I feel that this should be more descriptive for your hardware and not just
> generic. You don't need to include the qcom, extension and you'll probably
> want to use a more descriptive vendor if you are adding imx5 specific data to
> the DT.

Perhaps two entries, one for imx and one for qcom? This headless mode 
can be used with any adreno GPU.

> >   	{ .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
>