diff mbox series

[4/6] drm/format-helper: Support the AB24 format

Message ID 20220905163300.391692-5-thierry.reding@gmail.com
State Changes Requested
Headers show
Series drm/simpledrm: Support system memory framebuffers | expand

Commit Message

Thierry Reding Sept. 5, 2022, 4:32 p.m. UTC
From: Thierry Reding <treding@nvidia.com>

Add a conversion helper for the AB24 format to use in drm_fb_blit().

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 drivers/gpu/drm/drm_format_helper.c | 35 +++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

Comments

Thomas Zimmermann Sept. 7, 2022, 7:23 a.m. UTC | #1
Hi

Am 05.09.22 um 18:32 schrieb Thierry Reding:
> From: Thierry Reding <treding@nvidia.com>
> 
> Add a conversion helper for the AB24 format to use in drm_fb_blit().
> 
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
>   drivers/gpu/drm/drm_format_helper.c | 35 +++++++++++++++++++++++++++++
>   1 file changed, 35 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
> index 56642816fdff..d564412a816b 100644
> --- a/drivers/gpu/drm/drm_format_helper.c
> +++ b/drivers/gpu/drm/drm_format_helper.c
> @@ -503,6 +503,36 @@ static void drm_fb_rgb888_to_xrgb8888(struct iosys_map *dst, const unsigned int
>   		    drm_fb_rgb888_to_xrgb8888_line);
>   }
>   
> +static void drm_fb_xrgb8888_to_abgr8888_line(void *dbuf, const void *sbuf, unsigned int pixels)
> +{
> +	__le32 *dbuf32 = dbuf;
> +	const __le32 *sbuf32 = sbuf;
> +	unsigned int x;
> +	u32 pix;
> +
> +	for (x = 0; x < pixels; x++) {
> +		pix = le32_to_cpu(sbuf32[x]);
> +		pix = ((pix & 0xff000000) >> 24) << 24 |
> +		      ((pix & 0x00ff0000) >> 16) <<  0 |
> +		      ((pix & 0x0000ff00) >>  8) <<  8 |
> +		      ((pix & 0x000000ff) >>  0) << 16;
> +		*dbuf32++ = cpu_to_le32(pix);
> +	}
> +}

What does the Jetson device do with these alpha bits?

AFAIK the X channel's content is undefined. Shifting the bits into the A 
channel might result in wrong results in the general case. Better just 
set the alpha to 0xff unconditionally.

> +
> +static void drm_fb_xrgb8888_to_abgr8888(struct iosys_map *dst, const unsigned int *dst_pitch,
> +					const struct iosys_map *src,
> +					const struct drm_framebuffer *fb,
> +					const struct drm_rect *clip)
> +{
> +	static const u8 dst_pixsize[DRM_FORMAT_MAX_PLANES] = {
> +		4,
> +	};
> +
> +	drm_fb_xfrm(dst, dst_pitch, dst_pixsize, src, fb, clip, false,
> +		    drm_fb_xrgb8888_to_abgr8888_line);
> +}
> +
>   static void drm_fb_xrgb8888_to_xrgb2101010_line(void *dbuf, const void *sbuf, unsigned int pixels)
>   {
>   	__le32 *dbuf32 = dbuf;
> @@ -672,6 +702,11 @@ int drm_fb_blit(struct iosys_map *dst, const unsigned int *dst_pitch, uint32_t d
>   			drm_fb_rgb565_to_xrgb8888(dst, dst_pitch, src, fb, clip);
>   			return 0;
>   		}
> +	} else if (dst_format == DRM_FORMAT_ABGR8888) {
> +		if (fb_format == DRM_FORMAT_XRGB8888) {
> +			drm_fb_xrgb8888_to_abgr8888(dst, dst_pitch, src, fb, clip);
> +			return 0;
> +		}

For the other alpha-containing formats, we treat them like non-alpha 
formats (see the top of this function). Maybe just do the same here and 
then implement the conversion as drm_fb_xrgb8888_to_xbgr8888() helpers?

Best regards
Thomas

>   	} else if (dst_format == DRM_FORMAT_XRGB2101010) {
>   		if (fb_format == DRM_FORMAT_XRGB8888) {
>   			drm_fb_xrgb8888_to_xrgb2101010(dst, dst_pitch, src, fb, clip);
Thierry Reding Sept. 14, 2022, 4:09 p.m. UTC | #2
On Wed, Sep 07, 2022 at 09:23:01AM +0200, Thomas Zimmermann wrote:
> Hi
> 
> Am 05.09.22 um 18:32 schrieb Thierry Reding:
> > From: Thierry Reding <treding@nvidia.com>
> > 
> > Add a conversion helper for the AB24 format to use in drm_fb_blit().
> > 
> > Signed-off-by: Thierry Reding <treding@nvidia.com>
> > ---
> >   drivers/gpu/drm/drm_format_helper.c | 35 +++++++++++++++++++++++++++++
> >   1 file changed, 35 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
> > index 56642816fdff..d564412a816b 100644
> > --- a/drivers/gpu/drm/drm_format_helper.c
> > +++ b/drivers/gpu/drm/drm_format_helper.c
> > @@ -503,6 +503,36 @@ static void drm_fb_rgb888_to_xrgb8888(struct iosys_map *dst, const unsigned int
> >   		    drm_fb_rgb888_to_xrgb8888_line);
> >   }
> > +static void drm_fb_xrgb8888_to_abgr8888_line(void *dbuf, const void *sbuf, unsigned int pixels)
> > +{
> > +	__le32 *dbuf32 = dbuf;
> > +	const __le32 *sbuf32 = sbuf;
> > +	unsigned int x;
> > +	u32 pix;
> > +
> > +	for (x = 0; x < pixels; x++) {
> > +		pix = le32_to_cpu(sbuf32[x]);
> > +		pix = ((pix & 0xff000000) >> 24) << 24 |
> > +		      ((pix & 0x00ff0000) >> 16) <<  0 |
> > +		      ((pix & 0x0000ff00) >>  8) <<  8 |
> > +		      ((pix & 0x000000ff) >>  0) << 16;
> > +		*dbuf32++ = cpu_to_le32(pix);
> > +	}
> > +}
> 
> What does the Jetson device do with these alpha bits?
> 
> AFAIK the X channel's content is undefined. Shifting the bits into the A
> channel might result in wrong results in the general case. Better just set
> the alpha to 0xff unconditionally.

I'm not exactly sure, so I'd have to do some digging. I suspect that
perhaps this might actually be XBGR rather than ABGR, so this may end up
doing nothing. EFI FB reports this as ABGR, at least if I read the
output right, so that's what I went with for the DT implementation.

> > +
> > +static void drm_fb_xrgb8888_to_abgr8888(struct iosys_map *dst, const unsigned int *dst_pitch,
> > +					const struct iosys_map *src,
> > +					const struct drm_framebuffer *fb,
> > +					const struct drm_rect *clip)
> > +{
> > +	static const u8 dst_pixsize[DRM_FORMAT_MAX_PLANES] = {
> > +		4,
> > +	};
> > +
> > +	drm_fb_xfrm(dst, dst_pitch, dst_pixsize, src, fb, clip, false,
> > +		    drm_fb_xrgb8888_to_abgr8888_line);
> > +}
> > +
> >   static void drm_fb_xrgb8888_to_xrgb2101010_line(void *dbuf, const void *sbuf, unsigned int pixels)
> >   {
> >   	__le32 *dbuf32 = dbuf;
> > @@ -672,6 +702,11 @@ int drm_fb_blit(struct iosys_map *dst, const unsigned int *dst_pitch, uint32_t d
> >   			drm_fb_rgb565_to_xrgb8888(dst, dst_pitch, src, fb, clip);
> >   			return 0;
> >   		}
> > +	} else if (dst_format == DRM_FORMAT_ABGR8888) {
> > +		if (fb_format == DRM_FORMAT_XRGB8888) {
> > +			drm_fb_xrgb8888_to_abgr8888(dst, dst_pitch, src, fb, clip);
> > +			return 0;
> > +		}
> 
> For the other alpha-containing formats, we treat them like non-alpha formats
> (see the top of this function). Maybe just do the same here and then
> implement the conversion as drm_fb_xrgb8888_to_xbgr8888() helpers?

Yeah, that's probably for the best. None of the boot splash uses alpha
as far as I can tell and neither does the kernel framebuffer console, so
there's really little point in trying to support it.

Thierry
diff mbox series

Patch

diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
index 56642816fdff..d564412a816b 100644
--- a/drivers/gpu/drm/drm_format_helper.c
+++ b/drivers/gpu/drm/drm_format_helper.c
@@ -503,6 +503,36 @@  static void drm_fb_rgb888_to_xrgb8888(struct iosys_map *dst, const unsigned int
 		    drm_fb_rgb888_to_xrgb8888_line);
 }
 
+static void drm_fb_xrgb8888_to_abgr8888_line(void *dbuf, const void *sbuf, unsigned int pixels)
+{
+	__le32 *dbuf32 = dbuf;
+	const __le32 *sbuf32 = sbuf;
+	unsigned int x;
+	u32 pix;
+
+	for (x = 0; x < pixels; x++) {
+		pix = le32_to_cpu(sbuf32[x]);
+		pix = ((pix & 0xff000000) >> 24) << 24 |
+		      ((pix & 0x00ff0000) >> 16) <<  0 |
+		      ((pix & 0x0000ff00) >>  8) <<  8 |
+		      ((pix & 0x000000ff) >>  0) << 16;
+		*dbuf32++ = cpu_to_le32(pix);
+	}
+}
+
+static void drm_fb_xrgb8888_to_abgr8888(struct iosys_map *dst, const unsigned int *dst_pitch,
+					const struct iosys_map *src,
+					const struct drm_framebuffer *fb,
+					const struct drm_rect *clip)
+{
+	static const u8 dst_pixsize[DRM_FORMAT_MAX_PLANES] = {
+		4,
+	};
+
+	drm_fb_xfrm(dst, dst_pitch, dst_pixsize, src, fb, clip, false,
+		    drm_fb_xrgb8888_to_abgr8888_line);
+}
+
 static void drm_fb_xrgb8888_to_xrgb2101010_line(void *dbuf, const void *sbuf, unsigned int pixels)
 {
 	__le32 *dbuf32 = dbuf;
@@ -672,6 +702,11 @@  int drm_fb_blit(struct iosys_map *dst, const unsigned int *dst_pitch, uint32_t d
 			drm_fb_rgb565_to_xrgb8888(dst, dst_pitch, src, fb, clip);
 			return 0;
 		}
+	} else if (dst_format == DRM_FORMAT_ABGR8888) {
+		if (fb_format == DRM_FORMAT_XRGB8888) {
+			drm_fb_xrgb8888_to_abgr8888(dst, dst_pitch, src, fb, clip);
+			return 0;
+		}
 	} else if (dst_format == DRM_FORMAT_XRGB2101010) {
 		if (fb_format == DRM_FORMAT_XRGB8888) {
 			drm_fb_xrgb8888_to_xrgb2101010(dst, dst_pitch, src, fb, clip);