[PATCH] fbdev: core: tileblit: Implement missing margin clearing for tileblit

[Helge Deller]

On 2/1/25 09:18, Soci/Singular wrote:
> I was wondering why there's garbage at the bottom of the screen when
> tile blitting is used with an odd mode like 1080, 600 or 200. Sure there's
> only space for half a tile but the same area is clean when the buffer
> is bitmap.
>
> Then later I found that it's supposed to be cleaned but that's not
> implemented. So I took what's in bitblit and adapted it for tileblit.
>
> This implementation was tested for both the horizontal and vertical case,
> and now does the same as what's done for bitmap buffers.
>
> If anyone is interested to reproduce the problem then I could bet that'd
> be on a S3 or Ark. Just set up a mode with an odd line count and make
> sure that the virtual size covers the complete tile at the bottom. E.g.
> for 600 lines that's 608 virtual lines for a 16 tall tile. Then the
> bottom area should be cleaned.
>
> For the right side it's more difficult as there the drivers won't let an
> odd size happen, unless the code is modified. But once it reports back a
> few pixel columns short then fbcon won't use the last column. With the
> patch that column is now clean.
>
> Btw. the virtual size should be rounded up by the driver for both axes
> (not only the horizontal) so that it's dividable by the tile size.
> That's a driver bug but correcting it is not in scope for this patch.
>
> Implement missing margin clearing for tileblit
>
> Signed-off-by: Zsolt Kajtar <soci at c64.rulez.org>

applied to fbdev git tree.

Helge

> ---
>   drivers/video/fbdev/core/tileblit.c | 37 ++++++++++++++++++++++++++++-
>   1 file changed, 36 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/video/fbdev/core/tileblit.c b/drivers/video/fbdev/core/tileblit.c
> index eff7ec4da..98e528d38 100644
> --- a/drivers/video/fbdev/core/tileblit.c
> +++ b/drivers/video/fbdev/core/tileblit.c
> @@ -76,7 +76,42 @@ static void tile_putcs(struct vc_data *vc, struct fb_info *info,
>   static void tile_clear_margins(struct vc_data *vc, struct fb_info *info,
>   			       int color, int bottom_only)
>   {
> -	return;
> +	unsigned int cw = vc->vc_font.width;
> +	unsigned int ch = vc->vc_font.height;
> +	unsigned int rw = info->var.xres - (vc->vc_cols*cw);
> +	unsigned int bh = info->var.yres - (vc->vc_rows*ch);
> +	unsigned int rs = info->var.xres - rw;
> +	unsigned int bs = info->var.yres - bh;
> +	unsigned int vwt = info->var.xres_virtual / cw;
> +	unsigned int vht = info->var.yres_virtual / ch;
> +	struct fb_tilerect rect;
> +
> +	rect.index = vc->vc_video_erase_char &
> +		((vc->vc_hi_font_mask) ? 0x1ff : 0xff);
> +	rect.fg = color;
> +	rect.bg = color;
> +
> +	if ((int) rw > 0 && !bottom_only) {
> +		rect.sx = (info->var.xoffset + rs + cw - 1) / cw;
> +		rect.sy = 0;
> +		rect.width = (rw + cw - 1) / cw;
> +		rect.height = vht;
> +		if (rect.width + rect.sx > vwt)
> +			rect.width = vwt - rect.sx;
> +		if (rect.sx < vwt)
> +			info->tileops->fb_tilefill(info, &rect);
> +	}
> +
> +	if ((int) bh > 0) {
> +		rect.sx = info->var.xoffset / cw;
> +		rect.sy = (info->var.yoffset + bs) / ch;
> +		rect.width = rs / cw;
> +		rect.height = (bh + ch - 1) / ch;
> +		if (rect.height + rect.sy > vht)
> +			rect.height = vht - rect.sy;
> +		if (rect.sy < vht)
> +			info->tileops->fb_tilefill(info, &rect);
> +	}
>   }
>
>   static void tile_cursor(struct vc_data *vc, struct fb_info *info, bool enable,