On 29/11/2022 03:13, Doug Anderson wrote:
Hi,
On Fri, Nov 25, 2022 at 2:54 AM Qiqi Zhang <eddy.zhang@xxxxxxxxxxxxxx> wrote:
According to the description in ti-sn65dsi86's datasheet:
CHA_HSYNC_POLARITY:
0 = Active High Pulse. Synchronization signal is high for the sync
pulse width. (default)
1 = Active Low Pulse. Synchronization signal is low for the sync
pulse width.
CHA_VSYNC_POLARITY:
0 = Active High Pulse. Synchronization signal is high for the sync
pulse width. (Default)
1 = Active Low Pulse. Synchronization signal is low for the sync
pulse width.
We should only set these bits when the polarity is negative.
Signed-off-by: Qiqi Zhang <eddy.zhang@xxxxxxxxxxxxxx>
---
drivers/gpu/drm/bridge/ti-sn65dsi86.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
index 3c3561942eb6..eb24322df721 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
@@ -931,9 +931,9 @@ static void ti_sn_bridge_set_video_timings(struct ti_sn65dsi86 *pdata)
&pdata->bridge.encoder->crtc->state->adjusted_mode;
u8 hsync_polarity = 0, vsync_polarity = 0;
- if (mode->flags & DRM_MODE_FLAG_PHSYNC)
+ if (mode->flags & DRM_MODE_FLAG_NHSYNC)
hsync_polarity = CHA_HSYNC_POLARITY;
- if (mode->flags & DRM_MODE_FLAG_PVSYNC)
+ if (mode->flags & DRM_MODE_FLAG_NVSYNC)
vsync_polarity = CHA_VSYNC_POLARITY;
Looks right to me.
Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
I've never seen the polarity matter for any eDP panels I've worked
with, which presumably explains why this was wrong for so long. As far
Afaik, DP doesn't have sync polarity as such (neither does DSI), and the
sync polarity is just "metadata". So if you're in full-DP domain, I
don't see why it would matter. I guess it becomes relevant when you
convert from DP to some other bus format.
as I can tell, it's been wrong since the start. Probably you should
have:
Fixes: a095f15c00e2 ("drm/bridge: add support for sn65dsi86 bridge driver")
I put this on a sc7180-trogdor-lazor device and it didn't make
anything worse. Since the sync polarity never mattered to begin with,
I guess this isn't a surprise. ...so I guess that's a weak tested-by:
Tested-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
I'm happy to land this patch, but sounds like we're hoping to get
extra testing so I'll hold off for now.
Looks fine to me and works for me with my DP monitor.
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
Tomi
