Date:   Mon, 21 Oct 2019 14:41:22 +0000
From:   Mihail Atanassov <Mihail.Atanassov@....com>
To:     Ayan Halder <Ayan.Halder@....com>
CC:     Andrzej Pietrasiewicz <andrzej.p@...labora.com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        David Airlie <airlied@...ux.ie>,
        Liviu Dudau <Liviu.Dudau@....com>,
        "james qian wang (Arm Technology China)" <james.qian.wang@....com>,
        "linux-rockchip@...ts.infradead.org" 
        <linux-rockchip@...ts.infradead.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "kernel@...labora.com" <kernel@...labora.com>,
        Sean Paul <sean@...rly.run>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        nd <nd@....com>
Subject: Re: [PATCH 1/2] drm/arm: Factor out generic afbc helpers

Hi Andrzej,

On Monday, 21 October 2019 14:50:14 BST Ayan Halder wrote:
> On Fri, Oct 11, 2019 at 01:18:10PM +0200, Andrzej Pietrasiewicz wrote:
> > These are useful for other users of afbc, e.g. rockchip.
> > 
> > Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@...labora.com>
> 
> Hi Andrzej,
> 
> Thanks a lot for doing this. Much appreciated. :)
> It was on our TODO list for a long time.

Seconded, thanks for the patch!

> 
> I have cc-ed james.qian.wang@....com, Mihail.Atanassov@....com for
> their comments as well.
> 
> > ---
> >  drivers/gpu/drm/Kconfig          |   4 ++
> >  drivers/gpu/drm/Makefile         |   1 +
> >  drivers/gpu/drm/arm/Kconfig      |   1 +
> >  drivers/gpu/drm/arm/malidp_drv.c |  58 ++--------------
> >  drivers/gpu/drm/drm_afbc.c       | 114 +++++++++++++++++++++++++++++++
> >  include/drm/drm_afbc.h           |  25 +++++++
> >  6 files changed, 149 insertions(+), 54 deletions(-)
> >  create mode 100644 drivers/gpu/drm/drm_afbc.c
> >  create mode 100644 include/drm/drm_afbc.h
> > 
> > diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> > index 3c88420e3497..00e3f90557f4 100644
> > --- a/drivers/gpu/drm/Kconfig
> > +++ b/drivers/gpu/drm/Kconfig
> > @@ -195,6 +195,10 @@ config DRM_SCHED
> >  	tristate
> >  	depends on DRM
> >  
> > +config DRM_AFBC
> > +	tristate
> > +	depends on DRM
> Adding a 'help' would be great here. Stealing the first line from
> https://www.kernel.org/doc/html/latest/gpu/afbc.html
> 
> "AFBC is a proprietary lossless image compression protocol and format.
> It provides fine-grained random access and minimizes the amount of
> data transferred between IP blocks."
> 
> > +
> >  source "drivers/gpu/drm/i2c/Kconfig"
> >  
> >  source "drivers/gpu/drm/arm/Kconfig"
> > diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> > index 9f0d2ee35794..55368b668355 100644
> > --- a/drivers/gpu/drm/Makefile
> > +++ b/drivers/gpu/drm/Makefile
> > @@ -31,6 +31,7 @@ drm-$(CONFIG_OF) += drm_of.o
> >  drm-$(CONFIG_AGP) += drm_agpsupport.o
> >  drm-$(CONFIG_DEBUG_FS) += drm_debugfs.o drm_debugfs_crc.o
> >  drm-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
> > +drm-$(CONFIG_DRM_AFBC) += drm_afbc.o
> >  
> >  drm_vram_helper-y := drm_gem_vram_helper.o \
> >  		     drm_vram_helper_common.o \
> > diff --git a/drivers/gpu/drm/arm/Kconfig b/drivers/gpu/drm/arm/Kconfig
> > index a204103b3efb..25c3dc408cda 100644
> > --- a/drivers/gpu/drm/arm/Kconfig
> > +++ b/drivers/gpu/drm/arm/Kconfig
> > @@ -29,6 +29,7 @@ config DRM_MALI_DISPLAY
> >  	select DRM_KMS_HELPER
> >  	select DRM_KMS_CMA_HELPER
> >  	select DRM_GEM_CMA_HELPER
> > +	select DRM_AFBC
> >  	select VIDEOMODE_HELPERS
> >  	help
> >  	  Choose this option if you want to compile the ARM Mali Display
> > diff --git a/drivers/gpu/drm/arm/malidp_drv.c b/drivers/gpu/drm/arm/malidp_drv.c
> > index f25ec4382277..a67b69e08f63 100644
> > --- a/drivers/gpu/drm/arm/malidp_drv.c
> > +++ b/drivers/gpu/drm/arm/malidp_drv.c

This file is GPL-2.0-only. Shouldn't this be preserved when the
substantive bit of the code in drm_afbc.c comes from here?

> > @@ -16,6 +16,7 @@
> >  #include <linux/debugfs.h>
> >  
> >  #include <drm/drmP.h>
> > +#include <drm/drm_afbc.h>
> >  #include <drm/drm_atomic.h>
> >  #include <drm/drm_atomic_helper.h>
> >  #include <drm/drm_crtc.h>
> > @@ -33,8 +34,6 @@
> >  #include "malidp_hw.h"
> >  
> >  #define MALIDP_CONF_VALID_TIMEOUT	250
> > -#define AFBC_HEADER_SIZE		16
> > -#define AFBC_SUPERBLK_ALIGNMENT		128
> >  
> >  static void malidp_write_gamma_table(struct malidp_hw_device *hwdev,
> >  				     u32 data[MALIDP_COEFFTAB_NUM_COEFFS])
> > @@ -275,24 +274,8 @@ malidp_verify_afbc_framebuffer_caps(struct drm_device *dev,
> >  					mode_cmd->modifier[0]) == false)
> >  		return false;
> >  
> > -	if (mode_cmd->offsets[0] != 0) {
> > -		DRM_DEBUG_KMS("AFBC buffers' plane offset should be 0\n");
> > -		return false;
> > -	}
> > -
> > -	switch (mode_cmd->modifier[0] & AFBC_SIZE_MASK) {
> > -	case AFBC_SIZE_16X16:
> > -		if ((mode_cmd->width % 16) || (mode_cmd->height % 16)) {
> > -			DRM_DEBUG_KMS("AFBC buffers must be aligned to 16 pixels\n");
> > -			return false;
> > -		}
> > -		break;
> > -	default:
> > -		DRM_DEBUG_KMS("Unsupported AFBC block size\n");
> > -		return false;
> > -	}
> > -
> > -	return true;
> > +	return drm_afbc_check_offset(dev, mode_cmd) &&
> > +	       drm_afbc_check_size_align(dev, mode_cmd);
> >  }
> >  
> >  static bool
> > @@ -300,53 +283,20 @@ malidp_verify_afbc_framebuffer_size(struct drm_device *dev,
> >  				    struct drm_file *file,
> >  				    const struct drm_mode_fb_cmd2 *mode_cmd)
> >  {
> > -	int n_superblocks = 0;
> >  	const struct drm_format_info *info;
> >  	struct drm_gem_object *objs = NULL;
> > -	u32 afbc_superblock_size = 0, afbc_superblock_height = 0;
> > -	u32 afbc_superblock_width = 0, afbc_size = 0;
> >  	int bpp = 0;
> >  
> > -	switch (mode_cmd->modifier[0] & AFBC_SIZE_MASK) {
> > -	case AFBC_SIZE_16X16:
> > -		afbc_superblock_height = 16;
> > -		afbc_superblock_width = 16;
> > -		break;
> > -	default:
> > -		DRM_DEBUG_KMS("AFBC superblock size is not supported\n");
> > -		return false;
> > -	}
> > -
> >  	info = drm_get_format_info(dev, mode_cmd);
> > -
> > -	n_superblocks = (mode_cmd->width / afbc_superblock_width) *
> > -		(mode_cmd->height / afbc_superblock_height);
> > -
> >  	bpp = malidp_format_get_bpp(info->format);
> >  
> > -	afbc_superblock_size = (bpp * afbc_superblock_width * afbc_superblock_height)
> > -				/ BITS_PER_BYTE;
> > -
> > -	afbc_size = ALIGN(n_superblocks * AFBC_HEADER_SIZE, AFBC_SUPERBLK_ALIGNMENT);
> > -	afbc_size += n_superblocks * ALIGN(afbc_superblock_size, AFBC_SUPERBLK_ALIGNMENT);
> > -
> > -	if ((mode_cmd->width * bpp) != (mode_cmd->pitches[0] * BITS_PER_BYTE)) {
> > -		DRM_DEBUG_KMS("Invalid value of (pitch * BITS_PER_BYTE) (=%u) "
> > -			      "should be same as width (=%u) * bpp (=%u)\n",
> > -			      (mode_cmd->pitches[0] * BITS_PER_BYTE),
> > -			      mode_cmd->width, bpp);
> > -		return false;
> > -	}
> > -
> >  	objs = drm_gem_object_lookup(file, mode_cmd->handles[0]);
> >  	if (!objs) {
> >  		DRM_DEBUG_KMS("Failed to lookup GEM object\n");
> >  		return false;
> >  	}
> >  
> > -	if (objs->size < afbc_size) {
> > -		DRM_DEBUG_KMS("buffer size (%zu) too small for AFBC buffer size = %u\n",
> > -			      objs->size, afbc_size);
> > +	if (!drm_afbc_check_fb_size(dev, mode_cmd, objs, bpp)) {
> >  		drm_gem_object_put_unlocked(objs);
> >  		return false;
> >  	}
> Also can you do the code refactoring for komeda driver as well.
> specifically komeda_fb_afbc_size_check(). I will let
> james.qian.wang@....com and Mihail.Atanassov@....com have their
> opinion on this.

I'd say that it'd be really nice to get this work done for us ;)
but it doesn't have to be in this patch but rather in a follow-up.

> 
> > diff --git a/drivers/gpu/drm/drm_afbc.c b/drivers/gpu/drm/drm_afbc.c
> > new file mode 100644
> > index 000000000000..3e8a9225fd2e
> > --- /dev/null
> > +++ b/drivers/gpu/drm/drm_afbc.c
> > @@ -0,0 +1,114 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * (C) 2019 Collabora Ltd.
> > + *
> > + * author: Andrzej Pietrasiewicz <andrzej.p@...labora.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>
> > +
> > +#define AFBC_HEADER_SIZE		16
> > +#define AFBC_SUPERBLK_ALIGNMENT		128
> > +
> > +bool drm_afbc_check_offset(struct drm_device *dev,
> > +			   const struct drm_mode_fb_cmd2 *mode_cmd)
> > +{
> > +	if (mode_cmd->offsets[0] != 0) {
> > +		DRM_DEBUG_KMS("AFBC buffers' plane offset should be 0\n");
> > +		return false;
> > +	}
> > +
> > +	return true;
> > +}
> > +EXPORT_SYMBOL_GPL(drm_afbc_check_offset);
> > +
> > +bool drm_afbc_check_size_align(struct drm_device *dev,
> > +			       const struct drm_mode_fb_cmd2 *mode_cmd)
> > +{
> > +
> > +	switch (mode_cmd->modifier[0] & AFBC_FORMAT_MOD_BLOCK_SIZE_MASK) {
> > +	case AFBC_FORMAT_MOD_BLOCK_SIZE_16x16:
> > +		if ((mode_cmd->width % 16) || (mode_cmd->height % 16)) {
> > +			DRM_DEBUG_KMS(
> > +				"AFBC buffer must be aligned to 16 pixels\n"
> > +			);
> > +			return false;
> > +		}
> > +		break;
> > +	case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8:
> > +		/* fall through */
> > +	case AFBC_FORMAT_MOD_BLOCK_SIZE_64x4:
> > +		/* fall through */
> > +	case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8_64x4:
> > +		/* fall through */
> > +	default:
> > +		DRM_DEBUG_KMS("Unsupported AFBC block size\n");
> > +		return false;
> > +	}
> > +
> > +	return true;
> > +}
> > +EXPORT_SYMBOL_GPL(drm_afbc_check_size_align);
> > +
> > +bool drm_afbc_check_fb_size(struct drm_device *dev,
> > +			    const struct drm_mode_fb_cmd2 *mode_cmd,
> > +			    struct drm_gem_object *objs, int bpp)
> > +{
> > +	int n_superblocks = 0;
> > +	u32 afbc_superblock_size = 0, afbc_superblock_height = 0;
> > +	u32 afbc_superblock_width = 0, afbc_size = 0;
> > +
> > +	switch (mode_cmd->modifier[0] & AFBC_FORMAT_MOD_BLOCK_SIZE_MASK) {
> > +	case AFBC_FORMAT_MOD_BLOCK_SIZE_16x16:
> > +		afbc_superblock_height = 16;
> > +		afbc_superblock_width = 16;
> > +		break;
> > +	case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8:
> Copying from
> https://cgit.freedesktop.org/drm/drm-tip/tree/drivers/gpu/drm/arm/display/komeda/komeda_framebuffer.c#n60
>                 afbc_superblock_width = 32;
>                 afbc_superblock_height = 8;
> > +		/* fall through */
> > +	case AFBC_FORMAT_MOD_BLOCK_SIZE_64x4:
> > +		/* fall through */
> > +	case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8_64x4:
> > +		/* fall through */
> > +	default:
> > +		DRM_DEBUG_KMS("AFBC superblock size is not supported\n");
> > +		return false;
> > +	}
> Can you combine the two switch - case confitions (from this function
> and the one in drm_afbc_check_size_align()) and put it in a separate
> function (say drm_afbc_get_superblock_dimensions()) of its own ?
> This will help to avoid code repetition.
> 

I'm personally a bit on the fence about this - functions should ideally
do one thing. That shared helper would be both getting the dimensions
_and_ checking the mode_cmd is valid, so one place cares about one half
of the function's results, and the other - the second half. ¯\_O_/¯,
opinions, everybody has them :).

> > +
> > +	n_superblocks = (mode_cmd->width / afbc_superblock_width) *
> > +		(mode_cmd->height / afbc_superblock_height);
> > +
> > +	afbc_superblock_size =
> > +		(bpp * afbc_superblock_width * afbc_superblock_height)
> > +			/ BITS_PER_BYTE;
> > +
> > +	afbc_size = ALIGN(n_superblocks * AFBC_HEADER_SIZE,
> > +			  AFBC_SUPERBLK_ALIGNMENT);
> > +	afbc_size += n_superblocks *
> > +		ALIGN(afbc_superblock_size, AFBC_SUPERBLK_ALIGNMENT);
> > +
> > +	if ((mode_cmd->width * bpp) != (mode_cmd->pitches[0] * BITS_PER_BYTE)) {
> > +		DRM_DEBUG_KMS("Invalid value of (pitch * BITS_PER_BYTE) (=%u) should be same as width (=%u) * bpp (=%u)\n",
> > +			mode_cmd->pitches[0] * BITS_PER_BYTE,
> > +			mode_cmd->width, bpp
> > +		);
> > +		return false;
> > +	}
> > +
> > +	if (objs->size < afbc_size) {
> > +		DRM_DEBUG_KMS("buffer size (%zu) too small for AFBC buffer size = %u\n",
> > +			objs->size, afbc_size
> > +		);
> > +
> > +		return false;
> > +	}
> > +
> > +	return true;
> > +}
> > +EXPORT_SYMBOL(drm_afbc_check_fb_size);
> > diff --git a/include/drm/drm_afbc.h b/include/drm/drm_afbc.h
> > new file mode 100644
> > index 000000000000..ce39c850217b
> > --- /dev/null
> > +++ b/include/drm/drm_afbc.h
> > @@ -0,0 +1,25 @@
> > +/* SPDX-License-Identifier: GPL-2.0+ */
> > +/*
> > + * (C) 2019 Collabora Ltd.
> > + *
> > + * author: Andrzej Pietrasiewicz <andrzej.p@...labora.com>
> > + *
> > + */
> > +#ifndef __DRM_AFBC_H__
> > +#define __DRM_AFBC_H__
> > +
> > +struct drm_device;
> > +struct drm_mode_fb_cmd2;
> > +struct drm_gem_object;
> > +
> > +bool drm_afbc_check_offset(struct drm_device *dev,
> > +			   const struct drm_mode_fb_cmd2 *mode_cmd);
> > +
> > +bool drm_afbc_check_size_align(struct drm_device *dev,
> > +			       const struct drm_mode_fb_cmd2 *mode_cmd);
> > +
> > +bool drm_afbc_check_fb_size(struct drm_device *dev,
> > +			    const struct drm_mode_fb_cmd2 *mode_cmd,
> > +			    struct drm_gem_object *objs, int bpp);
> > +
> > +#endif /* __DRM_AFBC_H__ */
> > --
> > 2.17.1
> > 
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@...ts.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 

Overall the patch LGTM as-is, nice and straightforward
mostly-cut-n-paste, just let's sort out the SPDX identifier question
I have, then I'll be happy.

-- 
Mihail

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