Re: [PATCH V2] drm/vkms: Decouple config data for configfs

From: Melissa Wen
Date: Sat Jan 02 2021 - 18:47:24 EST


Hi Sumera,

Thanks for your patch.
Please see some comments below.

On 01/02, Sumera Priyadarsini wrote:
> Currently, data for the device instance is held by vkms_device.
> Add a separate type, vkms_config to contain configuration details
> for the device and various modes to be later used by configfs.
> This config data stays constant once the device is created.
>
> Accordingly, add vkms_create and vkms_destroy to initialize/destroy
> device through configfs. Currently, they are being called from vkms_init
> and vkms_exit, but will be evoked from configfs later on. When configfs
> is added, device configuration- enabling/disabling features will
> be tracked by configfs and only vkms device lifetime will be kept track of
> by vkms_init and vkms_exit functions.

I didn't quite understand this very last sentence.

>
> Modify usage of enable_cursor feature to reflect the changes in
> relevant files.

Since the goal is also enabling/disabling writeback and vblank via a
future configfs support, it would be nice to see here this same cursor
adaptation applied to others, initially as a module parameter. For
writeback, it's really straightforward...

>
> Signed-off-by: Sumera Priyadarsini <sylphrenadin@xxxxxxxxx>
> Co-developed-by: Daniel Vetter <danvet.vetter@xxxxxxx>

There are some formatting details for credits, for example, including
the co-developer s-o-b. See here:
https://www.kernel.org/doc/html/latest/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by

> ---
> Changes in v2:
> - add Co-developed-by tag
>
> ---
> drivers/gpu/drm/vkms/vkms_drv.c | 40 ++++++++++++++++++++++++------
> drivers/gpu/drm/vkms/vkms_drv.h | 11 +++++---
> drivers/gpu/drm/vkms/vkms_output.c | 4 +--
> 3 files changed, 42 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
> index aef29393b811..6b33975a5cb2 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.c
> +++ b/drivers/gpu/drm/vkms/vkms_drv.c
> @@ -34,9 +34,9 @@
> #define DRIVER_MAJOR 1
> #define DRIVER_MINOR 0
>
> -static struct vkms_device *vkms_device;
> +static struct vkms_config *default_config;
>
> -bool enable_cursor = true;
> +static bool enable_cursor = true;
> module_param_named(enable_cursor, enable_cursor, bool, 0444);
> MODULE_PARM_DESC(enable_cursor, "Enable/Disable cursor support");
>
> @@ -122,10 +122,11 @@ static int vkms_modeset_init(struct vkms_device *vkmsdev)
> return vkms_output_init(vkmsdev, 0);
> }
>
> -static int __init vkms_init(void)
> +static int vkms_create(struct vkms_config *config)
> {
> int ret;
> struct platform_device *pdev;
> + struct vkms_device *vkms_device;
>
> pdev = platform_device_register_simple(DRIVER_NAME, -1, NULL, 0);
> if (IS_ERR(pdev))
> @@ -143,6 +144,8 @@ static int __init vkms_init(void)
> goto out_devres;
> }
> vkms_device->platform = pdev;
> + vkms_device->config = config;
> + config->dev = vkms_device;
>
> ret = dma_coerce_mask_and_coherent(vkms_device->drm.dev,
> DMA_BIT_MASK(64));
> @@ -179,21 +182,42 @@ static int __init vkms_init(void)
> return ret;
> }
>
> -static void __exit vkms_exit(void)
> +static int __init vkms_init(void)
> +{
> + struct vkms_config *config = kmalloc(sizeof(*config), GFP_KERNEL);
> +
> + default_config = config;
> +
> + config->cursor = enable_cursor;
> +
> + return vkms_create(config);
> +}
> +
> +static void vkms_destroy(struct vkms_config *config)
> {
> struct platform_device *pdev;
>
> - if (!vkms_device) {
> + if (!config->dev) {
> DRM_INFO("vkms_device is NULL.\n");
> return;
> }
>
> - pdev = vkms_device->platform;
> + pdev = config->dev->platform;
>
> - drm_dev_unregister(&vkms_device->drm);
> - drm_atomic_helper_shutdown(&vkms_device->drm);
> + drm_dev_unregister(&config->dev->drm);
> + drm_atomic_helper_shutdown(&config->dev->drm);
> devres_release_group(&pdev->dev, NULL);
> platform_device_unregister(pdev);
> +
> + config->dev = NULL;
> +}
> +
> +static void __exit vkms_exit(void)
> +{
> + if (default_config->dev)
> + vkms_destroy(default_config);
> +
> + kfree(default_config);
> }
>
> module_init(vkms_init);
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> index 5ed91ff08cb3..2fa0c52f1dd8 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.h
> +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> @@ -19,8 +19,6 @@
> #define XRES_MAX 8192
> #define YRES_MAX 8192
>
> -extern bool enable_cursor;
> -
> struct vkms_composer {
> struct drm_framebuffer fb;
> struct drm_rect src, dst;
> @@ -82,10 +80,17 @@ struct vkms_output {
> spinlock_t composer_lock;
> };
>
> +struct vkms_device;
> +struct vkms_config {
> + bool cursor;
> + /* only set when instantiated */
> + struct vkms_device *dev;
> +};
> struct vkms_device {
> struct drm_device drm;
> struct platform_device *platform;
> struct vkms_output output;
> + const struct vkms_config *config;
> };
>
> #define drm_crtc_to_vkms_output(target) \
> @@ -123,4 +128,4 @@ void vkms_set_composer(struct vkms_output *out, bool enabled);
> /* Writeback */
> int vkms_enable_writeback_connector(struct vkms_device *vkmsdev);
>
> -#endif /* _VKMS_DRV_H_ */
> +#endif /* _VKMS_DRV_H_ */
> \ No newline at end of file
> diff --git a/drivers/gpu/drm/vkms/vkms_output.c b/drivers/gpu/drm/vkms/vkms_output.c
> index 4a1848b0318f..8f3ffb28b9d1 100644
> --- a/drivers/gpu/drm/vkms/vkms_output.c
> +++ b/drivers/gpu/drm/vkms/vkms_output.c
> @@ -46,7 +46,7 @@ int vkms_output_init(struct vkms_device *vkmsdev, int index)
> if (IS_ERR(primary))
> return PTR_ERR(primary);
>
> - if (enable_cursor) {
> + if (vkmsdev->config->cursor) {
> cursor = vkms_plane_init(vkmsdev, DRM_PLANE_TYPE_CURSOR, index);
> if (IS_ERR(cursor)) {
> ret = PTR_ERR(cursor);
> @@ -98,7 +98,7 @@ int vkms_output_init(struct vkms_device *vkmsdev, int index)
> drm_crtc_cleanup(crtc);
>
> err_crtc:
> - if (enable_cursor)
> + if (vkmsdev->config->cursor)
> drm_plane_cleanup(cursor);
>
> err_cursor:
> --
> 2.25.1
>