On 09/09, Igor Matheus Andrade Torrente wrote: > Hi Mellisa, > > Thanks for the patch fixing my mistakes. > > On 9/9/22 08:41, Melissa Wen wrote: > > Replace vkms_formats macros for fixed-point operations with functions > > from drm/drm_fixed.h to do the same job and fix 32-bit compilation > > errors. > > > > Fixes: a19c2ac9858 ("drm: vkms: Add support to the RGB565 format") > > Tested-by: Sudip Mukherjee <sudipm.mukher...@gmail.com> > > Reported-by: Sudip Mukherjee <sudipm.mukher...@gmail.com> > > Reported-by: kernel test robot <l...@intel.com> > > Signed-off-by: Melissa Wen <m...@igalia.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..ddcd3cfeeaac 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); > > + s32 fp_rb_ratio = drm_fixp_div(drm_int2fixp(65535), 31); > > + s32 fp_g_ratio = drm_fixp_div(drm_int2fixp(65535), 63); > > I think you need to add `drm_int2fixp` to 31 and 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); > > + s32 fp_r = drm_int2fixp((rgb_565 >> 11) & 0x1f); > > + s32 fp_g = drm_int2fixp((rgb_565 >> 5) & 0x3f); > > + s32 fp_b = drm_int2fixp(rgb_565 & 0x1f); > > And we are cast implicitly from 64 bits int to 32 bits which is > implementation-defined AFAIK. So, probably we should be using `s64` for all > of these variables. > > I tested the patch. And I'm seeing some differences in the intermediate > results. From my testing, these changes solve those differences.
Hi Igor, Thanks for checking the calc results and all inputs provided. I just sent a second version, can you take a look? I replicated your suggestions for RGB565_to_argb_u16() in argb_u16_to_RGB565() and double-checked for i386 and arm. Let me know what you think. > > Another thing that may have an impact on the final output is the lack of > rounding in drm_fixed.h. This can potentially produce the wrong result. Yeah, I see... I can include a comment about the rounding issue for further improvements, or do you plan to work on it? Thanks, Melissa > > Thanks, > --- > Igor Torrente > > > 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); > > + s32 fp_rb_ratio = drm_fixp_div(drm_int2fixp(65535), 31); > > + s32 fp_g_ratio = drm_fixp_div(drm_int2fixp(65535), 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); > > + s32 fp_r = drm_int2fixp(in_pixels[x].r); > > + s32 fp_g = drm_int2fixp(in_pixels[x].g); > > + s32 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); > > } >
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