On Mon, Sep 4, 2017 at 9:43 AM, Daniel Vetter daniel@ffwll.ch wrote:
On Fri, Sep 01, 2017 at 11:46:29AM +0200, Linus Walleij wrote:
If we cannot find a panel, assume that the output from the PL111 is connected directly to a "dumb" VGA connector, so look up the connector from that bridge.
Signed-off-by: Linus Walleij linus.walleij@linaro.org
if (panel) { priv->panel = panel; priv->connector = panel->connector;
} else {priv->connector = drm_dumb_vga_get_connector(bridge);Why do you need to set this?
Essentially because drm_simple_display_pipe_init() require that you specify a connector in the last argument, so I have to get it from somewhere.
The only code I could find tries to set polarity values from bus_flags, and for VGA I'd assume you want to instead key this off the mode?
The usecase is that either a panel or a dumb VGA bridge is used (not both, luckily).
On *some* dumb VGA bridges, the polarity of the clock signal is inverted, i.e. it expects data to be clocked out on the negative edge rather than the positive edge. See: https://lists.freedesktop.org/archives/dri-devel/2017-September/151603.html
And the PL111 can control this in software, that is why it is inspecting the flags on the connector to figure out when to clock things out.
It seems logical to check the connector to figure out what clock edge it wants?
Wrt the more general problem: They way we solve this in the i915 atomic framework is that the various ->fixup calls fill out relevant fields in the drm_crtc_state. I guess we could add an ->atomic_check to bridges, add a bus_flags to drm_crtc_state (or maybe just let everyone patch up adjusted_mode->flags) instead?
Not quite following... I do need fixups to mask some modes off the PL111 but that would be on the driver side.
Yours, Linus Walleij