Re: [PATCH v2 1/2] drm: allow limiting the scatter list size.

[Daniel Vetter]

On Mon, Sep 7, 2020 at 8:39 AM Gerd Hoffmann <kraxel@xxxxxxxxxx> wrote:
>
> > > +   /**
> > > +    * @max_segment:
> > > +    *
> > > +    * Max size for scatter list segments.  When unset the default
> > > +    * (SCATTERLIST_MAX_SEGMENT) is used.
> > > +    */
> > > +   size_t max_segment;
> >
> > Is there no better place for this then "at the bottom"? drm_device is a
> > huge structure, piling stuff up randomly doesn't make it better :-)
>
> Moved next to the other gem fields for now (v3 posted).
>
> > I think ideally we'd have a gem substruct like we have on the modeset side
> > at least.
>
> Phew, that'll be quite some churn in the tree.  And there aren't that many
> gem-related fields in struct drm_device.
>
> So you are looking for something like below (header changes only)?

Hm yeah it's a lot less than I thought. And yes I think that would be neat.
-Daniel

>
> take care,
>   Gerd
>
> diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h
> index c455ef404ca6..950167ede98a 100644
> --- a/include/drm/drm_device.h
> +++ b/include/drm/drm_device.h
> @@ -299,22 +299,8 @@ struct drm_device {
>         /** @mode_config: Current mode config */
>         struct drm_mode_config mode_config;
>
> -       /** @object_name_lock: GEM information */
> -       struct mutex object_name_lock;
> -
> -       /** @object_name_idr: GEM information */
> -       struct idr object_name_idr;
> -
> -       /** @vma_offset_manager: GEM information */
> -       struct drm_vma_offset_manager *vma_offset_manager;
> -
> -       /**
> -        * @max_segment:
> -        *
> -        * Max size for scatter list segments for GEM objects.  When
> -        * unset the default (SCATTERLIST_MAX_SEGMENT) is used.
> -        */
> -       size_t max_segment;
> +       /** @gem_config: Current GEM config */
> +       struct drm_gem_config gem_config;
>
>         /** @vram_mm: VRAM MM memory manager */
>         struct drm_vram_mm *vram_mm;
> diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
> index 337a48321705..74129fb29fb8 100644
> --- a/include/drm/drm_gem.h
> +++ b/include/drm/drm_gem.h
> @@ -39,6 +39,25 @@
>
>  #include <drm/drm_vma_manager.h>
>
> +struct drm_gem_config {
> +       /** @object_name_lock: GEM information */
> +       struct mutex object_name_lock;
> +
> +       /** @object_name_idr: GEM information */
> +       struct idr object_name_idr;
> +
> +       /** @vma_offset_manager: GEM information */
> +       struct drm_vma_offset_manager *vma_offset_manager;
> +
> +       /**
> +        * @max_segment:
> +        *
> +        * Max size for scatter list segments for GEM objects.  When
> +        * unset the default (SCATTERLIST_MAX_SEGMENT) is used.
> +        */
> +       size_t max_segment;
> +};
> +
>  struct drm_gem_object;
>
>  /**
>
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch