Re: [PATCHv2 3/4] drm/komeda: use afbc helpers

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Nov 13, 2019 at 02:01:53AM +0000, james qian wang (Arm Technology China) wrote:
> On Fri, Nov 08, 2019 at 04:09:54PM +0000, Ayan Halder wrote:
> > On Mon, Nov 04, 2019 at 11:12:27PM +0100, Andrzej Pietrasiewicz wrote:
> > > There are afbc helpers available.
> > > 
> > > Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
> > > ---
> > >  .../arm/display/komeda/komeda_format_caps.h   |  1 -
> > >  .../arm/display/komeda/komeda_framebuffer.c   | 44 +++++++------------
> > >  2 files changed, 17 insertions(+), 28 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_format_caps.h b/drivers/gpu/drm/arm/display/komeda/komeda_format_caps.h
> > > index 32273cf18f7c..607eea80e60c 100644
> > > --- a/drivers/gpu/drm/arm/display/komeda/komeda_format_caps.h
> > > +++ b/drivers/gpu/drm/arm/display/komeda/komeda_format_caps.h
> > > @@ -33,7 +33,6 @@
> > >  
> > >  #define AFBC_TH_LAYOUT_ALIGNMENT	8
> > >  #define AFBC_HEADER_SIZE		16
> > > -#define AFBC_SUPERBLK_ALIGNMENT		128
> > >  #define AFBC_SUPERBLK_PIXELS		256
> > >  #define AFBC_BODY_START_ALIGNMENT	1024
> > >  #define AFBC_TH_BODY_START_ALIGNMENT	4096
> > > diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_framebuffer.c b/drivers/gpu/drm/arm/display/komeda/komeda_framebuffer.c
> > > index 1b01a625f40e..e9c87551a5b8 100644
> > > --- a/drivers/gpu/drm/arm/display/komeda/komeda_framebuffer.c
> > > +++ b/drivers/gpu/drm/arm/display/komeda/komeda_framebuffer.c
> > > @@ -4,6 +4,7 @@
> > >   * Author: James.Qian.Wang <james.qian.wang@arm.com>
> > >   *
> > >   */
> > > +#include <drm/drm_afbc.h>
> > >  #include <drm/drm_device.h>
> > >  #include <drm/drm_fb_cma_helper.h>
> > >  #include <drm/drm_gem.h>
> > > @@ -43,8 +44,7 @@ komeda_fb_afbc_size_check(struct komeda_fb *kfb, struct drm_file *file,
> > >  	struct drm_framebuffer *fb = &kfb->base;
> > >  	const struct drm_format_info *info = fb->format;
> > >  	struct drm_gem_object *obj;
> > > -	u32 alignment_w = 0, alignment_h = 0, alignment_header, n_blocks, bpp;
> > > -	u64 min_size;
> > > +	u32 alignment_w = 0, alignment_h = 0, alignment_header, bpp;
> > >  
> > >  	obj = drm_gem_object_lookup(file, mode_cmd->handles[0]);
> > >  	if (!obj) {
> > > @@ -52,19 +52,15 @@ komeda_fb_afbc_size_check(struct komeda_fb *kfb, struct drm_file *file,
> > >  		return -ENOENT;
> > >  	}
> > >  
> > > -	switch (fb->modifier & AFBC_FORMAT_MOD_BLOCK_SIZE_MASK) {
> > > -	case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8:
> > > -		alignment_w = 32;
> > > -		alignment_h = 8;
> > > -		break;
> > > -	case AFBC_FORMAT_MOD_BLOCK_SIZE_16x16:
> > > -		alignment_w = 16;
> > > -		alignment_h = 16;
> > > -		break;
> > > -	default:
> > > -		WARN(1, "Invalid AFBC_FORMAT_MOD_BLOCK_SIZE: %lld.\n",
> > > -		     fb->modifier & AFBC_FORMAT_MOD_BLOCK_SIZE_MASK);
> > > -		break;
> > > +	if (!drm_afbc_get_superblk_wh(fb->modifier, &alignment_w, &alignment_h))
> > > +		return -EINVAL;
> > > +
> > > +	if ((alignment_w != 16 || alignment_h != 16) &&
> > > +	    (alignment_w != 32 || alignment_h != 8)) {
> > > +		DRM_DEBUG_KMS("Unsupported afbc tile w/h [%d/%d]\n",
> > > +			      alignment_w, alignment_h);
> > > +
> > > +		return -EINVAL;
> > To be honest, the previous code looks much more readable
> > >  	}
> > >  
> > >  	/* tiled header afbc */
> > > @@ -84,20 +80,14 @@ komeda_fb_afbc_size_check(struct komeda_fb *kfb, struct drm_file *file,
> > >  		goto check_failed;
> > >  	}
> > >  
> > > -	n_blocks = (kfb->aligned_w * kfb->aligned_h) / AFBC_SUPERBLK_PIXELS;
> > > -	kfb->offset_payload = ALIGN(n_blocks * AFBC_HEADER_SIZE,
> > > -				    alignment_header);
> > > -
> > >  	bpp = komeda_get_afbc_format_bpp(info, fb->modifier);
> > > -	kfb->afbc_size = kfb->offset_payload + n_blocks *
> > > -			 ALIGN(bpp * AFBC_SUPERBLK_PIXELS / 8,
> > > -			       AFBC_SUPERBLK_ALIGNMENT);
> > > -	min_size = kfb->afbc_size + fb->offsets[0];
> > > -	if (min_size > obj->size) {
> > > -		DRM_DEBUG_KMS("afbc size check failed, obj_size: 0x%zx. min_size 0x%llx.\n",
> > > -			      obj->size, min_size);
> > We need kfb->offset_payload and kfb->afbc_size to set some registers
> > in d71_layer_update(). At this moment I feel like punching myself for
> > making the suggestion to consider abstracting some of the komeda's afbc
> > checks. To me it does not look like komeda(in the current shape) can take
> > much advantage of the generic _afbc_fb_check() function (as was suggested
> > previously by Danvet).
> > 
> > However, I will let james.qian.wang@arm.com,
> > Mihail.Atanassov@arm.com, Ben.Davis@arm.com comment here to see if
> > there could be a way of abstracting the afbc bits from komeda.
> >
> 
> Hi all:
> 
> Since the current generic drm_afbc helpers only support afbc_1.1, but
> komeda needs support both afbc1.1/1.2, so I think we can:
> - Add afbc1.2 support to drm afbc helpers.
> - for the afbc_payload_offset, can we add this member to
>   drm_framebuffer ?
> - The aligned_w/h are important for afbc, so can we have them in
>   drm_framebuffer ?  

How expensive is it to recompute these from a struct drm_framebuffer?

I'd just go with one function which computes all these derived values, and
stuffs them into a struct drm_afbc. Then drivers call that once or so.

For reworking drm_framebuffer itself I think it's probably a bit too
earlier. And if we do it, we should maybe go a bit more bold, aiming to
property-fy all the framebuffer settings, maybe even making it extensible,
and have drivers handle a corresponding drm_framebuffer_state.

A third option would be to create a drm_afbc_framebuffer which embeds
drm_framebuffer and which drivers would need to use. But also feels a bit
like too much churn. Recomputing should be quick enough and much easier.
-Daniel

> 
> Thanks
> James
> 
> > Thanks anyways for taking a stab at this.
> > -Ayan
> > > +
> > > +	if (!drm_afbc_check_fb_size(mode_cmd->pitches[0], bpp,
> > > +				    mode_cmd->width, mode_cmd->height,
> > > +				    alignment_w, alignment_h,
> > > +				    obj->size, mode_cmd->offsets[0],
> > > +				    AFBC_SUPERBLK_ALIGNMENT))
> > >  		goto check_failed;
> > > -	}
> > >  
> > >  	fb->obj[0] = obj;
> > >  	return 0;
> > > -- 
> > > 2.17.1

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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