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

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

Hi

Am 26.09.24 um 15:07 schrieb Tomi Valkeinen:
> 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?

If ywrap doesn't work and no one complained, can we remove it? The rest 
of the code is equivalent to drm_fbdev_dma.c, so we could remove omap's 
implementation entirely.

Best regards
Thomas

>  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);
> >   }

--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)