Re: [PATCH 2/4] drm: use convert_lines() in xrgb8888_to_rgb565 helpers.

From: Noralf TrÃnnes
Date: Tue Apr 09 2019 - 15:40:16 EST

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In reply to: Gerd Hoffmann: "[PATCH 2/4] drm: use convert_lines() in xrgb8888_to_rgb565 helpers."
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Den 09.04.2019 13.59, skrev Gerd Hoffmann:
> Also add two conversion functions for the swab / not swab cases.
> That way we have to check the swab flag only once.
>
> Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_format_helper.c | 117 +++++++++++++++-------------
> 1 file changed, 62 insertions(+), 55 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
> index f32e0173600c..b8d17cd0a9f8 100644
> --- a/drivers/gpu/drm/drm_format_helper.c
> +++ b/drivers/gpu/drm/drm_format_helper.c
> @@ -38,6 +38,46 @@ static struct drm_format_convert convert_swab16 = {
> .func = convert_swab16_fn,
> };
>
> +static void convert_xrgb8888_to_rgb565_fn(void *dst, void *src, u32 pixels)
> +{
> + u32 *sbuf = src;
> + u16 *dbuf = dst;
> + u32 x;
> +
> + for (x = 0; x < pixels; x++) {
> + dbuf[x] = ((sbuf[x] & 0x00F80000) >> 8) |
> + ((sbuf[x] & 0x0000FC00) >> 5) |
> + ((sbuf[x] & 0x000000F8) >> 3);
> + }
> +}
> +
> +static struct drm_format_convert convert_xrgb8888_to_rgb565 = {
> + .dst_cpp = 2,
> + .src_cpp = 4,
> + .func = convert_xrgb8888_to_rgb565_fn,
> +};
> +
> +static void convert_xrgb8888_to_rgb565_swab_fn(void *dst, void *src, u32 pixels)
> +{
> + u32 *sbuf = src;
> + u16 *dbuf = dst;
> + u16 val16;
> + u32 x;
> +
> + for (x = 0; x < pixels; x++) {
> + val16 = ((sbuf[x] & 0x00F80000) >> 8) |
> + ((sbuf[x] & 0x0000FC00) >> 5) |
> + ((sbuf[x] & 0x000000F8) >> 3);
> + dbuf[x] = swab16(val16);
> + }
> +}
> +
> +static struct drm_format_convert convert_xrgb8888_to_rgb565_swap = {
> + .dst_cpp = 2,
> + .src_cpp = 4,
> + .func = convert_xrgb8888_to_rgb565_swab_fn,
> +};
> +

I find that drm_format_convert makes the code more difficult to read.
The only shared code is the xrgb8888 to rgb565 conversion.

Can we do something like this instead:

static void drm_fb_xrgb8888_to_rgb565_line(u16 *dst, u32 *src, unsigned
int width, bool swap)
{
unsigned int x;

for (x = 0; x < width; x++) {
u16 val = ((*src & 0x00F80000) >> 8) |
((*src & 0x0000FC00) >> 5) |
((*src & 0x000000F8) >> 3);
src++;
if (swap)
*dst++ = swab16(val);
else
*dst++ = val;
}
}

void drm_fb_xrgb8888_to_rgb565(void *dst, void *vaddr,
struct drm_framebuffer *fb,
struct drm_rect *clip, bool swap)
{
void *src = vaddr + clip_offset(clip, fb->pitches[0], 4);
unsigned width = clip->x2 - clip->x1;
unsigned height = clip->y2 - clip->y1;
size_t src_clip_pitch = width * 4;
size_t dst_clip_pitch = width * 2;
unsigned int y;
void *sbuf;

/*
* The cma memory is write-combined so reads are uncached.
* Speed up by fetching one line at a time.
*/
sbuf = kmalloc(src_clip_pitch, GFP_KERNEL);
if (!sbuf)
return;

for (y = 0; y < height; y++) {
memcpy(sbuf, src, src_clip_pitch);

drm_fb_xrgb8888_to_rgb565_line(dst, sbuf, width, swap);

src += fb->pitches[0];
dst += dst_clip_pitch;
}

kfree(sbuf);
}
EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb565);

void drm_fb_xrgb8888_to_rgb565_dstclip(void __iomem *dst,
unsigned int dst_pitch,
void *vaddr, struct drm_framebuffer *fb,
struct drm_rect *clip, bool swap)
{
void *src = vaddr + clip_offset(clip, fb->pitches[0], 4);
unsigned width = clip->x2 - clip->x1;
unsigned height = clip->y2 - clip->y1;
size_t dst_clip_pitch = width * 2;
unsigned int y;
void *dbuf;

dst += clip_offset(clip, dst_pitch, 2);

dbuf = kmalloc(dst_clip_pitch, GFP_KERNEL);
if (!dbuf)
return;

for (y = 0; y < height; y++) {
drm_fb_xrgb8888_to_rgb565_line(dbuf, src, width, swap);

memcpy_toio(dst, dbuf, dst_clip_pitch);

src += fb->pitches[0];
dst += dst_pitch;
}

kfree(dbuf);
}
EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb565_dstclip);

Other things I noticed:

drm_fb_memcpy() is just a wrapper around drm_fb_memcpy_lines() and
drm_fb_memcpy_dstclip() around drm_fb_memcpy_lines_toio(). They can be
merged.

checkpatch gave this:

WARNING: Use #include <linux/io.h> instead of <asm/io.h>
#50: FILE: drivers/gpu/drm/drm_format_helper.c:14:
+#include <asm/io.h>

Noralf.

> static void convert_lines(void *dst, unsigned int dst_pitch,
> void *src, unsigned int src_pitch,
> unsigned int pixels,
> @@ -152,44 +192,6 @@ void drm_fb_swab16(u16 *dst, void *vaddr, struct drm_framebuffer *fb,
> }
> EXPORT_SYMBOL(drm_fb_swab16);
>
> -static void drm_fb_xrgb8888_to_rgb565_lines(void *dst, unsigned int dst_pitch,
> - void *src, unsigned int src_pitch,
> - unsigned int src_linelength,
> - unsigned int lines,
> - bool swap)
> -{
> - unsigned int linepixels = src_linelength / sizeof(u32);
> - unsigned int x, y;
> - u32 *sbuf;
> - u16 *dbuf, val16;
> -
> - /*
> - * The cma memory is write-combined so reads are uncached.
> - * Speed up by fetching one line at a time.
> - */
> - sbuf = kmalloc(src_linelength, GFP_KERNEL);
> - if (!sbuf)
> - return;
> -
> - for (y = 0; y < lines; y++) {
> - memcpy(sbuf, src, src_linelength);
> - dbuf = dst;
> - for (x = 0; x < linepixels; x++) {
> - val16 = ((sbuf[x] & 0x00F80000) >> 8) |
> - ((sbuf[x] & 0x0000FC00) >> 5) |
> - ((sbuf[x] & 0x000000F8) >> 3);
> - if (swap)
> - *dbuf++ = swab16(val16);
> - else
> - *dbuf++ = val16;
> - }
> - src += src_pitch;
> - dst += dst_pitch;
> - }
> -
> - kfree(sbuf);
> -}
> -
> /**
> * drm_fb_xrgb8888_to_rgb565 - Convert XRGB8888 to RGB565 clip buffer
> * @dst: RGB565 destination buffer
> @@ -208,15 +210,17 @@ void drm_fb_xrgb8888_to_rgb565(void *dst, void *vaddr,
> struct drm_framebuffer *fb,
> struct drm_rect *clip, bool swap)
> {
> - unsigned int src_offset = (clip->y1 * fb->pitches[0])
> - + (clip->x1 * sizeof(u32));
> - size_t src_len = (clip->x2 - clip->x1) * sizeof(u32);
> - size_t dst_len = (clip->x2 - clip->x1) * sizeof(u16);
> + struct drm_format_convert *conv = swap
> + ? &convert_xrgb8888_to_rgb565_swap
> + : &convert_xrgb8888_to_rgb565;
> + unsigned int src_offset =
> + clip_offset(clip, fb->pitches[0], conv->src_cpp);
> + size_t pixels = (clip->x2 - clip->x1);
> + size_t lines = (clip->y2 - clip->y1);
>
> - drm_fb_xrgb8888_to_rgb565_lines(dst, dst_len,
> - vaddr + src_offset, fb->pitches[0],
> - src_len, clip->y2 - clip->y1,
> - swap);
> + convert_lines(dst, pixels * conv->dst_cpp,
> + vaddr + src_offset, fb->pitches[0],
> + pixels, lines, conv);
> }
> EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb565);
>
> @@ -239,16 +243,19 @@ void drm_fb_xrgb8888_to_rgb565_dstclip(void *dst, unsigned int dst_pitch,
> void *vaddr, struct drm_framebuffer *fb,
> struct drm_rect *clip, bool swap)
> {
> - unsigned int src_offset = (clip->y1 * fb->pitches[0])
> - + (clip->x1 * sizeof(u32));
> - unsigned int dst_offset = (clip->y1 * dst_pitch)
> - + (clip->x1 * sizeof(u16));
> - size_t src_len = (clip->x2 - clip->x1) * sizeof(u32);
> + struct drm_format_convert *conv = swap
> + ? &convert_xrgb8888_to_rgb565_swap
> + : &convert_xrgb8888_to_rgb565;
> + unsigned int src_offset =
> + clip_offset(clip, fb->pitches[0], conv->src_cpp);
> + unsigned int dst_offset =
> + clip_offset(clip, dst_pitch, conv->dst_cpp);
> + size_t pixels = (clip->x2 - clip->x1);
> + size_t lines = (clip->y2 - clip->y1);
>
> - drm_fb_xrgb8888_to_rgb565_lines(dst + dst_offset, dst_pitch,
> - vaddr + src_offset, fb->pitches[0],
> - src_len, clip->y2 - clip->y1,
> - swap);
> + convert_lines(dst + dst_offset, dst_pitch,
> + vaddr + src_offset, fb->pitches[0],
> + pixels, lines, conv);
> }
> EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb565_dstclip);
>
>

Next message: Xiaochen Shen: "[PATCH 1/2] x86/resctrl: Fix repeating rdtgroup mode initialization"
Previous message: Rajat Jain: "Re: [PATCH v3 2/3] platform/x86: intel_pmc_core: Allow to dump debug registers on S0ix failure"
In reply to: Gerd Hoffmann: "[PATCH 2/4] drm: use convert_lines() in xrgb8888_to_rgb565 helpers."
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