drm/mcde: Support DPI output

This implements support for DPI output using the port node
in the device tree to connect a DPI LCD display to the
MCDE. The block also supports TV-out but we leave that
for another day when we have a hardware using it.

We implement parsing and handling of the "port" node,
and follow that to the DPI endpoint.

The clock divider used by the MCDE to divide down the
"lcdclk" (this has been designed for TV-like frequencies)
is represented by an ordinary clock provider internally
in the MCDE. This idea was inspired by the PL111 solution
by Eric Anholt: the divider also works very similar to
the Pl111 clock divider.

We take care to clear up some errors regarding the number
of available formatters and their type. We have 6 DSI
formatters and 2 DPI formatters.

Tested on the Samsung GT-I9070 Janice mobile phone.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Stephan Gerhold <stephan@gerhold.net>
Cc: phone-devel@vger.kernel.org
Cc: upstreaming@lists.sr.ht
Link: https://patchwork.freedesktop.org/patch/msgid/20201112142925.2571179-2-linus.walleij@linaro.org

drm/mcde: Enable the DSI link with display

The MCDE DSI link hardware which is modeled like a bridge
in DRM, connected further to the panel bridge, creating
a pipeline.

We have been using the .pre_enable(), .enable(),
.disable() and .post_disable() callbacks from the bridge
to set this up in a chained manner: first the display
controller goes online and then in successive order
each bridge in the pipeline. Inside DRM it works
like this:

drm_atomic_helper_commit_tail()
drm_atomic_helper_commit_modeset_enables()
struct drm_crtc_helper_funcs .atomic_enable()
struct drm_simple_display_pipe_funcs .enable()
MCDE display enable call
drm_atomic_bridge_chain_enable()
struct drm_bridge_funcs .pre_enable()
mcde_dsi_bridge_pre_enable()
panel_bridge_pre_enable()
struct drm_panel_funcs .prepare()
struct drm_bridge_funcs .enable()
mcde_dsi_bridge_enable()
panel_bridge_enable()
struct drm_panel_funcs .enable()

A similar sequence is executed for disabling.

Unfortunately this is not what the hardware needs: at
a certain stage in the enablement of the display
controller the DSI link needs to come up to support
video mode, else something (like a FIFO flow) locks
up the hardware and we never get picture.

Fix this by simply leaving the pre|enable and
post|disable callbacks unused, and establish two
cross-calls from the display controller to bring up
the DSI link at the right place in the display
bring-up sequence and vice versa in the shutdown
sequence.

For command mode displays, it works just fine to
also enable the display flow early. The only time
we hold it back right now is in one-shot mode,
on-demand display updates.

When combined with the previous patch and some patches
for the S6E63M0 display controller to support DSI
mode, this gives working display on the Samsung
GT-I8190 (Golden) phone. It has also been tested working
on the Samsung GT-S7710 (Skomer) phone.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: newbytee@protonmail.com
Cc: Stephan Gerhold <stephan@gerhold.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20200808223122.1492124-4-linus.walleij@linaro.org

drm/mcde: Fix display pipeline restart

To make sure that the MCDE is in a reasonable state during
set-up, perform a reset by power cycling the block by dropping
the on-chip regulator reference after probe. The display
subsystem (DSS) has no dedicated reset line so dropping
the EPOD regulator is the only real way of resetting it.

We introduce code to enable and disable the regulator in
the display enable/disable callbacks.

We move the generic MCDE setup such as muxing of DPI
signals and masking of interrupts to the display
handling.

When we drop the power to the whole display subsystem, not
only MCDE but also the DSI links lose their state. Therefore
we move the DSI block reset and hardware initialization
code to the mcde_dsi_bridge_pre_enable() callback so this
happens every time we start up the bridge, as we may have
lost the power.

We move the final disablement of the interrupts and
clocks to the mcde_dsi_bridge_post_disable() callback
rather than have it in the mcde_dsi_bridge_disable()
callback, as some control messages may still be sent
over the DSI host after the bridge has been shut down.

This (together with a patch for the corresponding
panel) makes the Samsung GT-S7710 successfully disable
and re-enable its display, cutting all power while
disabled and re-initializing the hardware when coming
back up.

Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Cc: newbytee@protonmail.com
Cc: Stephan Gerhold <stephan@gerhold.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20200808223122.1492124-3-linus.walleij@linaro.org

drm/mcde: Fix display data flow control

Revamp the way that the flow of data to the display is
defined.

I realized that the hardware supports something like
5 different modes of flow: oneshot, command with TE IRQ,
command with BTA (bus turn around) and TE IRQ, video
with TE IRQ and video without TE IRQ instead synchronizing
to the output of the MCDE DSI formatter.

Like before the selection of the type of flow is done
from the DSI driver when we attach it to the MCDE and we
get to know what the display wants.

The new video mode synchronization method from the MCDE DSI
formatter is used on some upstream devices such as Golden.
This is the new default for video mode: stateless panels
do not as a rule generate TE IRQs.

Another semantic change is that we stop sending
a TE request before every command when sending data to
a display in command mode: this should only be explicitly
requested when using BTA, according to the vendor driver.

This has been tested and works fine with the command mode
displays I have. (All that are supported upstream.)

Reported-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Stephan Gerhold <stephan@gerhold.net>
Cc: Stephan Gerhold <stephan@gerhold.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20200729090915.252730-2-linus.walleij@linaro.org

drm/mcde: Don't use drm_device->dev_private

Upcasting using a container_of macro is more typesafe, faster and
easier for the compiler to optimize.

v2: Move misplaced removal of double-assignment to this patch (Sam)

Reviewed-by: Linus Walleij <linus.walleij@linaro.org> (v1)
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200415074034.175360-30-daniel.vetter@ffwll.ch

drm/mcde: Fix frame sync setup for video mode panels

The MCDE driver differentiates only between "te_sync"
(for hardware TE0 sync) and software sync
(i.e. manually triggered updates) at the moment.

However, none of these options work correctly for video mode panels.
Therefore, we need to make some changes to make them work correctly:

- Select hardware sync coming from the (DSI) formatter.
- Keep the FIFO permanently enabled (otherwise MCDE will stop
feeding data to the panel).
- Skip manual software sync (this is not necessary in video mode).

Automatically detect if the connected panel is using video mode
and enable the necessary changes in that case.

Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20191106165835.2863-3-stephan@gerhold.net

drm/mcde: Add new driver for ST-Ericsson MCDE

This adds a new DRM driver for the ST-Ericsson Multi Channel
Display Engine, MCDE display controller.

This hardware has three independent DSI hosts and can composit
and display several memory buffers onto an LCD display. It
was developed for several years inside of ST-Ericsson and
shipped with a few million mobile phones from Sony and Samsung,
as well as with the Snowball community development board.

The driver is currently pretty rudimentary but supports a
simple framebuffer so we can get penguins and graphics when
using these SoCs.

Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190524092019.19355-1-linus.walleij@linaro.org