On Sat, Aug 25, 2018 at 03:51:52PM -0400, Mikulas Patocka wrote:
> Reading the registers without waiting for engine idle returns
> unpredictable values. These unpredictable values result in display
> corruption - if atyfb_imageblit reads the content of DP_PIX_WIDTH with the
> bit DP_HOST_TRIPLE_EN set (from previous invocation), the driver would
> never ever clear the bit, resulting in display corruption.
>
> We don't want to wait for idle because it would degrade performance, so
> this patch modifies the driver so that it never reads accelerator
> registers.
>
> HOST_CNTL doesn't have to be read, we can just write it with
> HOST_BYTE_ALIGN because no other part of the driver cares if
> HOST_BYTE_ALIGN is set.
>
> DP_PIX_WIDTH is written in the functions atyfb_copyarea and atyfb_fillrect
> with the default value and in atyfb_imageblit with the value set according
> to the source image data.
>
> Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
>
> ---
> drivers/video/fbdev/aty/mach64_accel.c | 22 +++++++++-------------
> 1 file changed, 9 insertions(+), 13 deletions(-)
>
> Index: linux-stable/drivers/video/fbdev/aty/mach64_accel.c
> ===================================================================
> --- linux-stable.orig/drivers/video/fbdev/aty/mach64_accel.c 2018-08-24 19:51:34.000000000 +0200
> +++ linux-stable/drivers/video/fbdev/aty/mach64_accel.c 2018-08-24 20:28:55.000000000 +0200
> @@ -127,7 +127,7 @@ void aty_init_engine(struct atyfb_par *p
>
> /* set host attributes */
> wait_for_fifo(13, par);
> - aty_st_le32(HOST_CNTL, 0, par);
> + aty_st_le32(HOST_CNTL, HOST_BYTE_ALIGN, par);
>
> /* set pattern attributes */
> aty_st_le32(PAT_REG0, 0, par);
> @@ -233,7 +233,8 @@ void atyfb_copyarea(struct fb_info *info
> rotation = rotation24bpp(dx, direction);
> }
>
> - wait_for_fifo(4, par);
> + wait_for_fifo(5, par);
> + aty_st_le32(DP_PIX_WIDTH, par->crtc.dp_pix_width, par);
> aty_st_le32(DP_SRC, FRGD_SRC_BLIT, par);
> aty_st_le32(SRC_Y_X, (sx << 16) | sy, par);
> aty_st_le32(SRC_HEIGHT1_WIDTH1, (width << 16) | area->height, par);
> @@ -269,7 +270,8 @@ void atyfb_fillrect(struct fb_info *info
> rotation = rotation24bpp(dx, DST_X_LEFT_TO_RIGHT);
> }
>
> - wait_for_fifo(3, par);
> + wait_for_fifo(4, par);
> + aty_st_le32(DP_PIX_WIDTH, par->crtc.dp_pix_width, par);
> aty_st_le32(DP_FRGD_CLR, color, par);
> aty_st_le32(DP_SRC,
> BKGD_SRC_BKGD_CLR | FRGD_SRC_FRGD_CLR | MONO_SRC_ONE,
> @@ -284,7 +286,7 @@ void atyfb_imageblit(struct fb_info *inf
> {
> struct atyfb_par *par = (struct atyfb_par *) info->par;
> u32 src_bytes, dx = image->dx, dy = image->dy, width = image->width;
> - u32 pix_width_save, pix_width, host_cntl, rotation = 0, src, mix;
> + u32 pix_width, rotation = 0, src, mix;
>
> if (par->asleep)
> return;
> @@ -296,8 +298,7 @@ void atyfb_imageblit(struct fb_info *inf
> return;
> }
>
> - pix_width = pix_width_save = aty_ld_le32(DP_PIX_WIDTH, par);
> - host_cntl = aty_ld_le32(HOST_CNTL, par) | HOST_BYTE_ALIGN;
> + pix_width = par->crtc.dp_pix_width;
>
> switch (image->depth) {
> case 1:
> @@ -370,12 +371,11 @@ void atyfb_imageblit(struct fb_info *inf
> mix = FRGD_MIX_D_XOR_S | BKGD_MIX_D;
> }
>
> - wait_for_fifo(6, par);
> - aty_st_le32(DP_WRITE_MASK, 0xFFFFFFFF, par);
Looks like init_engine() sets this one for us. So dropping should be ok.
> + wait_for_fifo(5, par);
> aty_st_le32(DP_PIX_WIDTH, pix_width, par);
> aty_st_le32(DP_MIX, mix, par);
> aty_st_le32(DP_SRC, src, par);
> - aty_st_le32(HOST_CNTL, host_cntl, par);
> + aty_st_le32(HOST_CNTL, HOST_BYTE_ALIGN, par);
Presumably we could drop this as well since it never changes.
Either way
Reviewed-by: Ville Syrjälä <syrjala@xxxxxx>
> aty_st_le32(DST_CNTL, DST_Y_TOP_TO_BOTTOM | DST_X_LEFT_TO_RIGHT | rotation, par);
>
> draw_rect(dx, dy, width, image->height, par);
> @@ -424,8 +424,4 @@ void atyfb_imageblit(struct fb_info *inf
> aty_st_le32(HOST_DATA0, get_unaligned_le32(pbitmap), par);
> }
> }
> -
> - /* restore pix_width */
> - wait_for_fifo(1, par);
> - aty_st_le32(DP_PIX_WIDTH, pix_width_save, par);
> }
--
Ville Syrjälä
syrjala@xxxxxx
http://www.sci.fi/~syrjala/
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