Re: [PATCH v5 79/80] drm/omapdrm: Remove struct drm_fb_helper from struct omap_fbdev.

[Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>]

Hi,

On 24/09/2024 10:13, Thomas Zimmermann wrote:
> Store instances of drm_fb_helper and struct omap_fbdev separately.
> This will allow omapdrm to use the common fbdev client, which allocates
> its own instance of struct drm_fb_helper.
>
> There is at most one instance of each per DRM device, so both can be
> referenced directly from the omap and DRM device structures. A later
> patchset might rework the common fbdev client to allow for storing
> both, drm_fb_helper and omap_fbdev, together in the same place.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Cc: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
> Acked-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
> ---
>   drivers/gpu/drm/omapdrm/omap_drv.h   |  3 ++
>   drivers/gpu/drm/omapdrm/omap_fbdev.c | 42 +++++++++++++++-------------
>   2 files changed, 26 insertions(+), 19 deletions(-)

The ywrap seems to be broken, but it's broken without this series too. 
With some quick hacks I managed to get the omapdrm's panning function 
called, and it works the same way with or without this series.

Tested on DRA76 EVM.

Reviewed-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>

For reference, in case someone is interested fixing omapdrm's ywrap code:

- get_fb() doesn't work. I don't understand the point of the function. 
It compares fbi->fix.id and MODULE_NAME, and the "fbi->fix.id" has 
changed along the years so the check no longer works. Afaik, the whole 
function is not needed, and we can just use fbi->par.

- omap_fbdev_pan_display() doesn't seem to get called when the console 
scrolls. I can get it called with an userspace app that does some y 
panning. Maybe FBINFO_HWACCEL_YWRAP is not supported anymore?

 Tomi

> diff --git a/drivers/gpu/drm/omapdrm/omap_drv.h b/drivers/gpu/drm/omapdrm/omap_drv.h
> index 4c7217b35f6b..d903568fd8cc 100644
> --- a/drivers/gpu/drm/omapdrm/omap_drv.h
> +++ b/drivers/gpu/drm/omapdrm/omap_drv.h
> @@ -32,6 +32,7 @@
>   #define MODULE_NAME     "omapdrm"
>   
>   struct omap_drm_usergart;
> +struct omap_fbdev;
>   
>   struct omap_drm_pipeline {
>   	struct drm_crtc *crtc;
> @@ -97,6 +98,8 @@ struct omap_drm_private {
>   
>   	/* memory bandwidth limit if it is needed on the platform */
>   	unsigned int max_bandwidth;
> +
> +	struct omap_fbdev *fbdev;
>   };
>   
>   
> diff --git a/drivers/gpu/drm/omapdrm/omap_fbdev.c b/drivers/gpu/drm/omapdrm/omap_fbdev.c
> index 523be34682ca..044e80403c3b 100644
> --- a/drivers/gpu/drm/omapdrm/omap_fbdev.c
> +++ b/drivers/gpu/drm/omapdrm/omap_fbdev.c
> @@ -13,6 +13,7 @@
>   #include <drm/drm_fourcc.h>
>   #include <drm/drm_framebuffer.h>
>   #include <drm/drm_gem_framebuffer_helper.h>
> +#include <drm/drm_managed.h>
>   #include <drm/drm_util.h>
>   
>   #include "omap_drv.h"
> @@ -26,10 +27,8 @@ module_param_named(ywrap, ywrap_enabled, bool, 0644);
>    * fbdev funcs, to implement legacy fbdev interface on top of drm driver
>    */
>   
> -#define to_omap_fbdev(x) container_of(x, struct omap_fbdev, base)
> -
>   struct omap_fbdev {
> -	struct drm_fb_helper base;
> +	struct drm_device *dev;
>   	bool ywrap_enabled;
>   
>   	/* for deferred dmm roll when getting called in atomic ctx */
> @@ -41,7 +40,7 @@ static struct drm_fb_helper *get_fb(struct fb_info *fbi);
>   static void pan_worker(struct work_struct *work)
>   {
>   	struct omap_fbdev *fbdev = container_of(work, struct omap_fbdev, work);
> -	struct drm_fb_helper *helper = &fbdev->base;
> +	struct drm_fb_helper *helper = fbdev->dev->fb_helper;
>   	struct fb_info *fbi = helper->info;
>   	struct drm_gem_object *bo = drm_gem_fb_get_obj(helper->fb, 0);
>   	int npages;
> @@ -55,24 +54,25 @@ FB_GEN_DEFAULT_DEFERRED_DMAMEM_OPS(omap_fbdev,
>   				   drm_fb_helper_damage_range,
>   				   drm_fb_helper_damage_area)
>   
> -static int omap_fbdev_pan_display(struct fb_var_screeninfo *var,
> -		struct fb_info *fbi)
> +static int omap_fbdev_pan_display(struct fb_var_screeninfo *var, struct fb_info *fbi)
>   {
>   	struct drm_fb_helper *helper = get_fb(fbi);
> -	struct omap_fbdev *fbdev = to_omap_fbdev(helper);
> +	struct omap_drm_private *priv;
> +	struct omap_fbdev *fbdev;
>   
>   	if (!helper)
>   		goto fallback;
>   
> +	priv = helper->dev->dev_private;
> +	fbdev = priv->fbdev;
> +
>   	if (!fbdev->ywrap_enabled)
>   		goto fallback;
>   
> -	if (drm_can_sleep()) {
> +	if (drm_can_sleep())
>   		pan_worker(&fbdev->work);
> -	} else {
> -		struct omap_drm_private *priv = helper->dev->dev_private;
> +	else
>   		queue_work(priv->wq, &fbdev->work);
> -	}
>   
>   	return 0;
>   
> @@ -92,7 +92,6 @@ static void omap_fbdev_fb_destroy(struct fb_info *info)
>   	struct drm_fb_helper *helper = info->par;
>   	struct drm_framebuffer *fb = helper->fb;
>   	struct drm_gem_object *bo = drm_gem_fb_get_obj(fb, 0);
> -	struct omap_fbdev *fbdev = to_omap_fbdev(helper);
>   
>   	DBG();
>   
> @@ -104,7 +103,7 @@ static void omap_fbdev_fb_destroy(struct fb_info *info)
>   
>   	drm_client_release(&helper->client);
>   	drm_fb_helper_unprepare(helper);
> -	kfree(fbdev);
> +	kfree(helper);
>   }
>   
>   /*
> @@ -128,9 +127,9 @@ static const struct fb_ops omap_fb_ops = {
>   static int omap_fbdev_create(struct drm_fb_helper *helper,
>   		struct drm_fb_helper_surface_size *sizes)
>   {
> -	struct omap_fbdev *fbdev = to_omap_fbdev(helper);
>   	struct drm_device *dev = helper->dev;
>   	struct omap_drm_private *priv = dev->dev_private;
> +	struct omap_fbdev *fbdev = priv->fbdev;
>   	struct drm_framebuffer *fb = NULL;
>   	union omap_gem_size gsize;
>   	struct fb_info *fbi = NULL;
> @@ -338,6 +337,7 @@ static const struct drm_client_funcs omap_fbdev_client_funcs = {
>   
>   void omap_fbdev_setup(struct drm_device *dev)
>   {
> +	struct omap_drm_private *priv = dev->dev_private;
>   	struct omap_fbdev *fbdev;
>   	struct drm_fb_helper *helper;
>   	int ret;
> @@ -345,24 +345,28 @@ void omap_fbdev_setup(struct drm_device *dev)
>   	drm_WARN(dev, !dev->registered, "Device has not been registered.\n");
>   	drm_WARN(dev, dev->fb_helper, "fb_helper is already set!\n");
>   
> -	fbdev = kzalloc(sizeof(*fbdev), GFP_KERNEL);
> +	fbdev = drmm_kzalloc(dev, sizeof(*fbdev), GFP_KERNEL);
>   	if (!fbdev)
>   		return;
> -	helper = &fbdev->base;
> +	fbdev->dev = dev;
> +	INIT_WORK(&fbdev->work, pan_worker);
> +
> +	priv->fbdev = fbdev;
>   
> +	helper = kzalloc(sizeof(*helper), GFP_KERNEL);
> +	if (!helper)
> +		return;
>   	drm_fb_helper_prepare(dev, helper, 32, &omap_fb_helper_funcs);
>   
>   	ret = drm_client_init(dev, &helper->client, "fbdev", &omap_fbdev_client_funcs);
>   	if (ret)
>   		goto err_drm_client_init;
>   
> -	INIT_WORK(&fbdev->work, pan_worker);
> -
>   	drm_client_register(&helper->client);
>   
>   	return;
>   
>   err_drm_client_init:
>   	drm_fb_helper_unprepare(helper);
> -	kfree(fbdev);
> +	kfree(helper);
>   }