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

[Jonathan marek]

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 at 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
> 
> 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
>   
>