linux-kernel - Re: [PATCH v2] drm/vkms: fix 32bit compilation error by replacing macros

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Date:   Sun, 11 Sep 2022 11:45:05 -0300
From:   Igor Matheus Andrade Torrente <igormtorrente@...il.com>
To:     Melissa Wen <mwen@...lia.com>, rodrigosiqueiramelo@...il.com,
        melissa.srw@...il.com, airlied@...ux.ie, daniel@...ll.ch
Cc:     Sudip Mukherjee <sudipm.mukherjee@...il.com>,
        Alex Deucher <alexdeucher@...il.com>,
        Alex Deucher <alexander.deucher@....com>,
        kernel test robot <lkp@...el.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] drm/vkms: fix 32bit compilation error by replacing
 macros

Reviewed-by: Igor Torrente <igormtorrente@...il.com>

On 9/10/22 16:03, Melissa Wen wrote:
> Replace vkms_formats macro for fixed-point operations with functions
> from drm/drm_fixed.h to do the same job and fix 32-bit compilation
> errors.
> 
> v2:
> - don't cast results to s32 (Igor)
> - add missing drm_fixp2int conversion (Igor)
> 
> Fixes: a19c2ac9858 ("drm: vkms: Add support to the RGB565 format")
> Tested-by: Sudip Mukherjee <sudipm.mukherjee@...il.com> (v1)
> Reviewed-by: Alex Deucher <alexander.deucher@....com> (v1)
> Reported-by: Sudip Mukherjee <sudipm.mukherjee@...il.com>
> Reported-by: kernel test robot <lkp@...el.com>
> Signed-off-by: Melissa Wen <mwen@...lia.com>
> ---
>   drivers/gpu/drm/vkms/vkms_formats.c | 53 +++++++++++------------------
>   1 file changed, 19 insertions(+), 34 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c
> index 300abb4d1dfe..d4950688b3f1 100644
> --- a/drivers/gpu/drm/vkms/vkms_formats.c
> +++ b/drivers/gpu/drm/vkms/vkms_formats.c
> @@ -1,27 +1,12 @@
>   // SPDX-License-Identifier: GPL-2.0+
>   
> -#include <drm/drm_rect.h>
> +#include <linux/kernel.h>
>   #include <linux/minmax.h>
> +#include <drm/drm_rect.h>
> +#include <drm/drm_fixed.h>
>   
>   #include "vkms_formats.h"
>   
> -/* The following macros help doing fixed point arithmetic. */
> -/*
> - * With Fixed-Point scale 15 we have 17 and 15 bits of integer and fractional
> - * parts respectively.
> - *  | 0000 0000 0000 0000 0.000 0000 0000 0000 |
> - * 31                                          0
> - */
> -#define SHIFT 15
> -
> -#define INT_TO_FIXED(a) ((a) << SHIFT)
> -#define FIXED_MUL(a, b) ((s32)(((s64)(a) * (b)) >> SHIFT))
> -#define FIXED_DIV(a, b) ((s32)(((s64)(a) << SHIFT) / (b)))
> -/* This macro converts a fixed point number to int, and round half up it */
> -#define FIXED_TO_INT_ROUND(a) (((a) + (1 << (SHIFT - 1))) >> SHIFT)
> -#define INT_TO_FIXED_DIV(a, b) (FIXED_DIV(INT_TO_FIXED(a), INT_TO_FIXED(b)))
> -#define INT_TO_FIXED_DIV(a, b) (FIXED_DIV(INT_TO_FIXED(a), INT_TO_FIXED(b)))
> -
>   static size_t pixel_offset(const struct vkms_frame_info *frame_info, int x, int y)
>   {
>   	return frame_info->offset + (y * frame_info->pitch)
> @@ -137,19 +122,19 @@ static void RGB565_to_argb_u16(struct line_buffer *stage_buffer,
>   	int x_limit = min_t(size_t, drm_rect_width(&frame_info->dst),
>   			       stage_buffer->n_pixels);
>   
> -	s32 fp_rb_ratio = INT_TO_FIXED_DIV(65535, 31);
> -	s32 fp_g_ratio = INT_TO_FIXED_DIV(65535, 63);
> +	s64 fp_rb_ratio = drm_fixp_div(drm_int2fixp(65535), drm_int2fixp(31));
> +	s64 fp_g_ratio = drm_fixp_div(drm_int2fixp(65535), drm_int2fixp(63));
>   
>   	for (size_t x = 0; x < x_limit; x++, src_pixels++) {
>   		u16 rgb_565 = le16_to_cpu(*src_pixels);
> -		s32 fp_r = INT_TO_FIXED((rgb_565 >> 11) & 0x1f);
> -		s32 fp_g = INT_TO_FIXED((rgb_565 >> 5) & 0x3f);
> -		s32 fp_b = INT_TO_FIXED(rgb_565 & 0x1f);
> +		s64 fp_r = drm_int2fixp((rgb_565 >> 11) & 0x1f);
> +		s64 fp_g = drm_int2fixp((rgb_565 >> 5) & 0x3f);
> +		s64 fp_b = drm_int2fixp(rgb_565 & 0x1f);
>   
>   		out_pixels[x].a = (u16)0xffff;
> -		out_pixels[x].r = FIXED_TO_INT_ROUND(FIXED_MUL(fp_r, fp_rb_ratio));
> -		out_pixels[x].g = FIXED_TO_INT_ROUND(FIXED_MUL(fp_g, fp_g_ratio));
> -		out_pixels[x].b = FIXED_TO_INT_ROUND(FIXED_MUL(fp_b, fp_rb_ratio));
> +		out_pixels[x].r = drm_fixp2int(drm_fixp_mul(fp_r, fp_rb_ratio));
> +		out_pixels[x].g = drm_fixp2int(drm_fixp_mul(fp_g, fp_g_ratio));
> +		out_pixels[x].b = drm_fixp2int(drm_fixp_mul(fp_b, fp_rb_ratio));
>   	}
>   }
>   
> @@ -248,17 +233,17 @@ static void argb_u16_to_RGB565(struct vkms_frame_info *frame_info,
>   	int x_limit = min_t(size_t, drm_rect_width(&frame_info->dst),
>   			    src_buffer->n_pixels);
>   
> -	s32 fp_rb_ratio = INT_TO_FIXED_DIV(65535, 31);
> -	s32 fp_g_ratio = INT_TO_FIXED_DIV(65535, 63);
> +	s64 fp_rb_ratio = drm_fixp_div(drm_int2fixp(65535), drm_int2fixp(31));
> +	s64 fp_g_ratio = drm_fixp_div(drm_int2fixp(65535), drm_int2fixp(63));
>   
>   	for (size_t x = 0; x < x_limit; x++, dst_pixels++) {
> -		s32 fp_r = INT_TO_FIXED(in_pixels[x].r);
> -		s32 fp_g = INT_TO_FIXED(in_pixels[x].g);
> -		s32 fp_b = INT_TO_FIXED(in_pixels[x].b);
> +		s64 fp_r = drm_int2fixp(in_pixels[x].r);
> +		s64 fp_g = drm_int2fixp(in_pixels[x].g);
> +		s64 fp_b = drm_int2fixp(in_pixels[x].b);
>   
> -		u16 r = FIXED_TO_INT_ROUND(FIXED_DIV(fp_r, fp_rb_ratio));
> -		u16 g = FIXED_TO_INT_ROUND(FIXED_DIV(fp_g, fp_g_ratio));
> -		u16 b = FIXED_TO_INT_ROUND(FIXED_DIV(fp_b, fp_rb_ratio));
> +		u16 r = drm_fixp2int(drm_fixp_div(fp_r, fp_rb_ratio));
> +		u16 g = drm_fixp2int(drm_fixp_div(fp_g, fp_g_ratio));
> +		u16 b = drm_fixp2int(drm_fixp_div(fp_b, fp_rb_ratio));
>   
>   		*dst_pixels = cpu_to_le16(r << 11 | g << 5 | b);
>   	}