Re: [PATCHv3/RFC 1/4] drm/arm: Factor out generic afbc helpers

["james qian wang (Arm Technology China)" <james.qian.wang@arm.com>]

On Mon, Nov 25, 2019 at 09:55:06AM +0100, Daniel Vetter wrote:
> On Thu, Nov 21, 2019 at 06:22:44PM +0100, Andrzej Pietrasiewicz wrote:
> > These are useful for other users of afbc, e.g. rockchip.
> > 
> > Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
> > ---
> >  drivers/gpu/drm/Makefile          |  2 +-
> >  drivers/gpu/drm/drm_afbc.c        | 84 +++++++++++++++++++++++++++++++
> >  drivers/gpu/drm/drm_fourcc.c      | 11 +++-
> >  drivers/gpu/drm/drm_framebuffer.c | 71 +++++++++++++++++++++++++-
> >  include/drm/drm_afbc.h            | 35 +++++++++++++
> >  5 files changed, 199 insertions(+), 4 deletions(-)
> >  create mode 100644 drivers/gpu/drm/drm_afbc.c
> >  create mode 100644 include/drm/drm_afbc.h
> > 
> > diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> > index d9bcc9f2a0a4..3a58f30b83a6 100644
> > --- a/drivers/gpu/drm/Makefile
> > +++ b/drivers/gpu/drm/Makefile
> > @@ -44,7 +44,7 @@ drm_kms_helper-y := drm_crtc_helper.o drm_dp_helper.o drm_dsc.o drm_probe_helper
> >  		drm_simple_kms_helper.o drm_modeset_helper.o \
> >  		drm_scdc_helper.o drm_gem_framebuffer_helper.o \
> >  		drm_atomic_state_helper.o drm_damage_helper.o \
> > -		drm_format_helper.o drm_self_refresh_helper.o
> > +		drm_format_helper.o drm_self_refresh_helper.o drm_afbc.o
> 
> Just a quick drive-by:
> - you can't put this into helpers and call from core code. This should be
>   core code. Also, I'd have just stuffed it into drm_format.c.
> 
> - If you want to keep your separate file, please include it in the doc
>   template, next to the format handling functions.
> >  
> >  drm_kms_helper-$(CONFIG_DRM_PANEL_BRIDGE) += bridge/panel.o
> >  drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o
> > diff --git a/drivers/gpu/drm/drm_afbc.c b/drivers/gpu/drm/drm_afbc.c
> > new file mode 100644
> > index 000000000000..f308c4719546
> > --- /dev/null
> > +++ b/drivers/gpu/drm/drm_afbc.c
> > @@ -0,0 +1,84 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * (C) 2019 Collabora Ltd.
> > + *
> > + * author: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
> > + *
> > + */
> > +#include <linux/module.h>
> > +
> > +#include <drm/drm_afbc.h>
> > +#include <drm/drm_device.h>
> > +#include <drm/drm_fourcc.h>
> > +#include <drm/drm_gem.h>
> > +#include <drm/drm_mode.h>
> > +#include <drm/drm_print.h>
> > +
> > +/**
> > + * drm_afbc_get_superblk_wh - extract afbc block width/height from modifier
> > + * @modifier: the modifier to be looked at
> > + * @w: address of a place to store the block width
> > + * @h: address of a place to store the block height
> > + *
> > + * Returns: true if the modifier describes a supported block size
> > + */
> > +bool drm_afbc_get_superblk_wh(u64 modifier, u32 *w, u32 *h)
> > +{
> > +	switch (modifier & AFBC_FORMAT_MOD_BLOCK_SIZE_MASK) {
> > +	case AFBC_FORMAT_MOD_BLOCK_SIZE_16x16:
> > +		*w = 16;
> > +		*h = 16;
> > +		break;
> > +	case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8:
> > +		*w = 32;
> > +		*h = 8;
> > +		break;
> > +	case AFBC_FORMAT_MOD_BLOCK_SIZE_64x4:
> > +		/* fall through */
> > +	case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8_64x4:
> > +		/* fall through */
> > +	default:
> > +		DRM_DEBUG_KMS("Invalid AFBC_FORMAT_MOD_BLOCK_SIZE: %lld.\n",
> > +			      modifier & AFBC_FORMAT_MOD_BLOCK_SIZE_MASK);
> > +		return false;
> > +	}
> > +	return true;
> > +}
> > +EXPORT_SYMBOL_GPL(drm_afbc_get_superblk_wh);
> > +
> > +/**
> > + * drm_afbc_get_parameters - extract afbc parameters from mode command
> > + * @mode_cmd: mode command to be looked at
> > + * @afbc: address of a struct to be filled in
> > + */
> > +void drm_afbc_get_parameters(const struct drm_mode_fb_cmd2 *mode_cmd,
> > +			     struct drm_afbc *afbc)
> > +{
> > +	drm_afbc_get_superblk_wh(mode_cmd->modifier[0],
> > +				 &afbc->tile_w, &afbc->tile_h);
> > +	afbc->width = mode_cmd->pitches[0];
> > +	afbc->height =
> > +		DIV_ROUND_UP(mode_cmd->height, afbc->tile_h) * afbc->tile_h;
> > +	afbc->offset = mode_cmd->offsets[0];
> > +}
> > +EXPORT_SYMBOL(drm_afbc_get_parameters);
> > +
> > +/**
> > + * drm_is_afbc - test if the modifier describes an afbc buffer
> > + * @modifier - modifier to be tested
> > + *
> > + * Returns: true if the modifier describes an afbc buffer
> > + */
> > +bool drm_is_afbc(u64 modifier)
> > +{
> > +	/* is it ARM AFBC? */
> > +	if ((modifier & DRM_FORMAT_MOD_ARM_AFBC(0)) == 0)
> > +		return false;
> > +
> > +	/* Block size must be known */
> > +	if ((modifier & AFBC_FORMAT_MOD_BLOCK_SIZE_MASK) == 0)
> > +		return false;
> > +
> > +	return true;
> > +}
> > +EXPORT_SYMBOL_GPL(drm_is_afbc);
> > diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
> > index c630064ccf41..8d9f197cc0ab 100644
> > --- a/drivers/gpu/drm/drm_fourcc.c
> > +++ b/drivers/gpu/drm/drm_fourcc.c
> > @@ -27,6 +27,7 @@
> >  #include <linux/export.h>
> >  #include <linux/kernel.h>
> >  
> > +#include <drm/drm_afbc.h>
> >  #include <drm/drm_device.h>
> >  #include <drm/drm_fourcc.h>
> >  
> > @@ -322,8 +323,14 @@ drm_get_format_info(struct drm_device *dev,
> >  {
> >  	const struct drm_format_info *info = NULL;
> >  
> > -	if (dev->mode_config.funcs->get_format_info)
> > -		info = dev->mode_config.funcs->get_format_info(mode_cmd);
> > +	/* bypass driver callback if afbc */
> > +	if (!drm_is_afbc(mode_cmd->modifier[0]))
> > +		if (dev->mode_config.funcs->get_format_info) {
> > +			const struct drm_mode_config_funcs *funcs;
> > +
> > +			funcs = dev->mode_config.funcs;
> > +			info = funcs->get_format_info(mode_cmd);
> > +		}
> >  
> >  	if (!info)
> >  		info = drm_format_info(mode_cmd->pixel_format);
> > diff --git a/drivers/gpu/drm/drm_framebuffer.c b/drivers/gpu/drm/drm_framebuffer.c
> > index 57564318ceea..303eea624a02 100644
> > --- a/drivers/gpu/drm/drm_framebuffer.c
> > +++ b/drivers/gpu/drm/drm_framebuffer.c
> > @@ -23,6 +23,7 @@
> >  #include <linux/export.h>
> >  #include <linux/uaccess.h>
> >  
> > +#include <drm/drm_afbc.h>
> >  #include <drm/drm_atomic.h>
> >  #include <drm/drm_atomic_uapi.h>
> >  #include <drm/drm_auth.h>
> > @@ -31,6 +32,7 @@
> >  #include <drm/drm_file.h>
> >  #include <drm/drm_fourcc.h>
> >  #include <drm/drm_framebuffer.h>
> > +#include <drm/drm_gem.h>
> >  #include <drm/drm_print.h>
> >  #include <drm/drm_util.h>
> >  
> > @@ -168,7 +170,69 @@ static int fb_plane_height(int height,
> >  	return DIV_ROUND_UP(height, format->vsub);
> >  }
> >  
> > +static int afbc_check(struct drm_file *file_priv,
> > +		      const struct drm_mode_fb_cmd2 *r, int i,
> > +		      const struct drm_format_info *info)
> > +{
> > +	struct drm_gem_object *obj;
> > +	int bpp = info->cpp[0] * 8;
> > +	int tiles;
> > +	u32 w, h, height, tile_sz, afbc_size;
> > +	int result = 0;
> > +
> > +	if (i) {
> > +		DRM_DEBUG_KMS("AFBC supported only for plane 0\n");
> > +
> > +		return 1;
> > +	}
> > +
> > +	/* get tile w/h */
> > +	if (!drm_afbc_get_superblk_wh(r->modifier[0], &w, &h))
> > +		return 1;
> > +
> > +	/* pitch must be divisible by tile width */
> > +	if (r->pitches[0] % w) {
> > +		DRM_DEBUG_KMS("Invalid pitch for plane %d\n", i);
> > +
> > +		return 1;
> > +	}
> > +
> > +	obj = drm_gem_object_lookup(file_priv, r->handles[0]);
> 
> I think this is a bit ugly ... I'd split this into a new
> framebuffer_check_post() function which is called after fb_create, at that
> point you do have the objects already looked up.
> 
> Also I suggested that this could be done as a helper implementation for
> fb_create, wrapping it around the default gem implementation. That way you
> could keep all the afbc stuff in helpers entirely (but drivers could screw
> things up, so there's a tradeoff).
> 
> What's definitely not ok is calling drm_gem_object_lookup unconditionally
> from core code here. For consistency I think the helper approach would be
> good, since currently the size related checks are done in
> drm_gem_fb_create() - i.e. in the helpers, not in core. Otoh having checks
> split like this is also ugly, so maybe we should have a
> framebuffer_check_post for everyone, and move all the size checks into
> core (not just for afbc).
> -Daniel
> 
> > +	if (!obj) {
> > +		DRM_DEBUG_KMS("Failed to lookup GEM object\n");
> > +
> > +		return 1;
> > +	}
> > +
> > +	/* estimate height based on tile size and height from userspace */
> > +	height = DIV_ROUND_UP(r->height, h) * h;
> > +
> > +	tiles = (r->pitches[0] / w) * (height / h);
> > +	afbc_size = ALIGN(tiles * AFBC_HEADER_SIZE, AFBC_SUPERBLK_ALIGNMENT);
> > +
> > +	tile_sz = (bpp * w * h) / BITS_PER_BYTE;
> > +	afbc_size += tiles * ALIGN(tile_sz, AFBC_SUPERBLK_ALIGNMENT);
> > +
> > +	result = obj->size < afbc_size;
> > +
> > +	drm_gem_object_put_unlocked(obj);
> > +
> > +	return result;
> > +}
> > +
> > +static int modifier_check(struct drm_file *file_priv,
> > +			  const struct drm_mode_fb_cmd2 *r, int i,
> > +			  const struct drm_format_info *info)
> > +{
> > +	/* non-afbc format */
> > +	if (!drm_is_afbc(r->modifier[i]))
> > +		return 0;
> > +
> > +	return afbc_check(file_priv, r, i, info);
> > +}
> > +
> >  static int framebuffer_check(struct drm_device *dev,
> > +			     struct drm_file *file_priv,
> >  			     const struct drm_mode_fb_cmd2 *r)
> >  {
> >  	const struct drm_format_info *info;
> > @@ -204,6 +268,9 @@ static int framebuffer_check(struct drm_device *dev,
> >  		unsigned int block_size = info->char_per_block[i];
> >  		u64 min_pitch = drm_format_info_min_pitch(info, i, width);
> >  
> > +		if (drm_is_afbc(r->modifier[i]))
> > +			block_size = 0;
> > +
> >  		if (!block_size && (r->modifier[i] == DRM_FORMAT_MOD_LINEAR)) {
> >  			DRM_DEBUG_KMS("Format requires non-linear modifier for plane %d\n", i);
> >  			return -EINVAL;
> > @@ -253,6 +320,8 @@ static int framebuffer_check(struct drm_device *dev,
> >  			break;
> >  
> >  		default:
> > +			if (modifier_check(file_priv, r, i, info))
> > +				return -EINVAL;
> >  			break;
> >  		}
> >  	}
> > @@ -317,7 +386,7 @@ drm_internal_framebuffer_create(struct drm_device *dev,
> >  		return ERR_PTR(-EINVAL);
> >  	}
> >  
> > -	ret = framebuffer_check(dev, r);
> > +	ret = framebuffer_check(dev, file_priv, r);
> >  	if (ret)
> >  		return ERR_PTR(ret);
> >  
> > diff --git a/include/drm/drm_afbc.h b/include/drm/drm_afbc.h
> > new file mode 100644
> > index 000000000000..fb4d4549f77e
> > --- /dev/null
> > +++ b/include/drm/drm_afbc.h
> > @@ -0,0 +1,35 @@
> > +/* SPDX-License-Identifier: GPL-2.0+ */
> > +/*
> > + * (C) 2019 Collabora Ltd.
> > + *
> > + * author: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
> > + *
> > + */
> > +#ifndef __DRM_AFBC_H__
> > +#define __DRM_AFBC_H__
> > +
> > +#include <linux/types.h>
> > +
> > +struct drm_device;
> > +struct drm_mode_fb_cmd2;
> > +struct drm_gem_object;
> > +
> > +struct drm_afbc {
> > +	u32 tile_w;
> > +	u32 tile_h;
> > +	u32 width;
> > +	u32 height;
> > +	u32 offset;
> > +};
> > +

Can we put a afbc ptr into drm_framebuffer, as the afbc extension if
the fb is afbc.
Since mostly this drm_afbc is enough for afbc support, but no need to
expose check func to driver, since per design the afbc modifier bits represent
all the requrement, the check is like a sanity check between the modifier and
fb info.

And we can also extend such afbc_info to all modifier which need an
extra check or extra info. like.

struct drm_framebuffer {
    ...
    union {    
        struct drm_afbc *afbc_info;
        void *mod_info; //extra modifier extension.  
    }
    ...
}

and such modifier info can be returned modifier_check()

drm_gem_fb_create_with_funcs()
{
    void *mod_info;

    if (!modifier)
        none_modifier_size_check();
    else if (afbc)
        mod_info = drm_afbc_size_check();
    else if (mode_config->fb_modifier_check())
        // for vendor specific modifier check
        mod_info = mode_config->fb_modifier_check();

    fb = drm_gem_fb_alloc();

    fb->mod_info = mod_info;
}

And in specific driver, you can directly convert the fb->mod_info to
your own modifier info. like current modifier is afbc, then

   struct drm_afbc *afbc_info = fb->mod_info;

Thanks
James
> > +#define AFBC_HEADER_SIZE		16
> > +#define AFBC_SUPERBLK_ALIGNMENT		128
> > +
> > +bool drm_afbc_get_superblk_wh(u64 modifier, u32 *w, u32 *h);
> > +
> > +void drm_afbc_get_parameters(const struct drm_mode_fb_cmd2 *mode_cmd,
> > +			     struct drm_afbc *afbc);
> > +
> > +bool drm_is_afbc(u64 modifier);
> > +
> > +#endif /* __DRM_AFBC_H__ */
> > -- 
> > 2.17.1
> > 
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
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