On 24/09/2019 16:17, Tomi Valkeinen wrote:

max_tu_symbol was programmed to TU_SIZE_RECOMMENDED - 1, which is not what the spec says. The spec says:

roundup ((input active video bandwidth in bytes/output active video bandwidth in bytes) * tu_size)

It is not quite clear what the above means, but calculating max_tu_symbol = (input Bps / output Bps) * tu_size seems to work and fixes the issues seen.

This fixes artifacts in some videomodes (e.g. 1024x768@60 on 2-lanes & 1.62Gbps was pretty bad for me).

Signed-off-by: Tomi Valkeinen tomi.valkeinen@ti.com

I could reproduce the problem and see that the patch fixes it, so:

Tested-by: Jyri Sarha jsarha@ti.com

---

drivers/gpu/drm/bridge/tc358767.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c index 13ade28a36a8..b6aa1bd47e1d 100644 --- a/drivers/gpu/drm/bridge/tc358767.c +++ b/drivers/gpu/drm/bridge/tc358767.c @@ -677,6 +677,8 @@ static int tc_set_video_mode(struct tc_data *tc, int upper_margin = mode->vtotal - mode->vsync_end; int lower_margin = mode->vsync_start - mode->vdisplay; int vsync_len = mode->vsync_end - mode->vsync_start;

• u32 bits_per_pixel = 24;

• u32 in_bw, out_bw;

  /*

  • Recommended maximum number of symbols transferred in a transfer unit:

@@ -684,7 +686,10 @@ static int tc_set_video_mode(struct tc_data *tc, * (output active video bandwidth in bytes)) * Must be less than tu_size. */

• max_tu_symbol = TU_SIZE_RECOMMENDED - 1;

• in_bw = mode->clock * bits_per_pixel / 8;

• out_bw = tc->link.base.num_lanes * tc->link.base.rate;

• max_tu_symbol = DIV_ROUND_UP(in_bw * TU_SIZE_RECOMMENDED, out_bw);

  dev_dbg(tc->dev, "set mode %dx%d\n", mode->hdisplay, mode->vdisplay);