On 2016-02-03 15:18, Stefan Agner wrote:
On 2016-02-03 06:00, Thierry Reding wrote:
On Wed, Jan 27, 2016 at 06:46:50PM -0800, Stefan Agner wrote: [...]
diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c index f97b73e..fa68b56 100644 --- a/drivers/gpu/drm/panel/panel-simple.c +++ b/drivers/gpu/drm/panel/panel-simple.c @@ -960,6 +960,8 @@ static const struct drm_display_mode nec_nl4827hc19_05b_mode = { .vsync_end = 272 + 2 + 4, .vtotal = 272 + 2 + 4 + 2, .vrefresh = 74,
- .flags = DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_NHSYNC |
DISPLAY_FLAGS_PIXDATA_POSEDGE,It doesn't seem like these two types of flags should be mixed because they overlap. DISPLAY_FLAGS_PIXDATA_POSEDGE has the same value as the DRM_MODE_FLAG_CSYNC define.
There are other entries such as hannstar_hsd100pxn1_timing which make use of DISPLAY_FLAGS too, hence I did not bother further. Having a conflict is definitely not what we want.
Oh, just realized, hannstar_hsd100pxn1_timing is actually a different type of struct, and for this struct the DISPALY_FLAGS make sense...
The definition of the DISPLAY_FLAGS_PIXDATA_POSEDGE is also not very clear to me. I don't think we have an equivalent DRM_MODE_FLAG_* but we could add one if there's really a need.
E.g. assuming a parallel video signal, the pixel data signals could be changing on positive or negative edge relative to the clock signal. Most displays _sample_ the data on rising edge, hence controllers should normally drive data on falling edge.
However, as always, there are exceptions to the rule, and one of the exception is Freescales default display for the Tower evaluation board. It samples data on falling edge, hence the controller should drive data on rising edge...
Yeah I also did not found an equivalent in DRM_MODE_FLAG_*. I have here also other displays where we would need this flag. The display-timings binds and enum display_flags support it too, hence I guess we should have it here too.
I will split out this patch from the patchset (I already applied the rest), add another patch to add the flag, make use of the flag in this patch and resend it as v2.
I realized that after this, there are only two flags which are not yet in DRM_MODE_FLAG: DE_LOW/DE_HIGH.
Thierry, what do you think, should I add these remaining two flags too?
-- Stefan