Re: [Intel-gfx] [PATCH v3 4/7] drm/fb-helper: Apply panel orientation connector prop to the primary plane

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Hi,

On 31-10-17 11:14, Daniel Vetter wrote:
On Mon, Oct 30, 2017 at 12:09:27PM +0100, Hans de Goede wrote:
Hi,

On 30-10-17 10:52, Daniel Vetter wrote:
On Mon, Oct 23, 2017 at 09:14:22AM +0200, Hans de Goede wrote:
Apply the "panel orientation" drm connector prop to the primary plane so
that fbcon and fbdev using userspace programs display the right way up.

Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=94894
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
Changes in v2:
-New patch in v2 of this patch-set

Changes in v3:
-Use a rotation member in struct drm_fb_helper_crtc and set that from
   drm_setup_crtcs instead of looping over all crtc's to find the right one
   later
-Since we now no longer look at rotation quirks directly in the fbcon code,
   set fb_info.fbcon_rotate_hint when the panel is not mounted upright and
   we cannot use hardware rotation
---
   drivers/gpu/drm/drm_fb_helper.c | 76 +++++++++++++++++++++++++++++++++++++++--
   include/drm/drm_fb_helper.h     |  8 +++++
   2 files changed, 82 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 116d1f1337c7..e0f95f2cc52f 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -41,6 +41,7 @@
   #include <drm/drm_atomic.h>
   #include <drm/drm_atomic_helper.h>
+#include "drm_crtc_internal.h"
   #include "drm_crtc_helper_internal.h"
   static bool drm_fbdev_emulation = true;
@@ -350,6 +351,7 @@ EXPORT_SYMBOL(drm_fb_helper_debug_leave);
   static int restore_fbdev_mode_atomic(struct drm_fb_helper *fb_helper, bool active)
   {
   	struct drm_device *dev = fb_helper->dev;
+	struct drm_plane_state *plane_state;
   	struct drm_plane *plane;
   	struct drm_atomic_state *state;
   	int i, ret;
@@ -368,8 +370,6 @@ static int restore_fbdev_mode_atomic(struct drm_fb_helper *fb_helper, bool activ
   retry:
   	plane_mask = 0;
   	drm_for_each_plane(plane, dev) {
-		struct drm_plane_state *plane_state;
-
   		plane_state = drm_atomic_get_plane_state(state, plane);
   		if (IS_ERR(plane_state)) {
   			ret = PTR_ERR(plane_state);
@@ -392,6 +392,11 @@ static int restore_fbdev_mode_atomic(struct drm_fb_helper *fb_helper, bool activ
   	for (i = 0; i < fb_helper->crtc_count; i++) {
   		struct drm_mode_set *mode_set = &fb_helper->crtc_info[i].mode_set;
+		struct drm_plane *primary = mode_set->crtc->primary;
+
+		/* Cannot fail as we've already gotten the plane state above */
+		plane_state = drm_atomic_get_new_plane_state(state, primary);
+		plane_state->rotation = fb_helper->crtc_info[i].rotation;
   		ret = __drm_atomic_helper_set_config(mode_set, state);
   		if (ret != 0)
@@ -2334,6 +2339,57 @@ static int drm_pick_crtcs(struct drm_fb_helper *fb_helper,
   	return best_score;
   }
+/*
+ * This function checks if rotation is necessary because of panel orientation
+ * and if it is, if it is supported.
+ * If rotation is necessary and supported, its gets set in fb_crtc.rotation.
+ * If rotation is necessary but not supported, a DRM_MODE_ROTATE_* flag gets
+ * or-ed into fb_helper->rotations. In drm_setup_crtcs_fb() we check if only
+ * one bit is set and then we set fb_info.fbcon_rotate_hint to make fbcon do
+ * the unsupported rotation.
+ */
+static void drm_setup_crtc_rotation(struct drm_fb_helper *fb_helper,
+				    struct drm_fb_helper_crtc *fb_crtc,
+				    struct drm_connector *connector)
+{
+	struct drm_plane *plane = fb_crtc->mode_set.crtc->primary;
+	uint64_t valid_mask = 0;
+	int i, rotation;
+
+	fb_crtc->rotation = DRM_MODE_ROTATE_0;
+
+	switch (connector->display_info.panel_orientation) {
+	case DRM_MODE_PANEL_ORIENTATION_BOTTOM_UP:
+		rotation = DRM_MODE_ROTATE_180;
+		break;
+	case DRM_MODE_PANEL_ORIENTATION_LEFT_UP:
+		rotation = DRM_MODE_ROTATE_90;
+		break;
+	case DRM_MODE_PANEL_ORIENTATION_RIGHT_UP:
+		rotation = DRM_MODE_ROTATE_270;
+		break;

For 90/270 hw rotation you need to flip the coordinates/sizes of the fb.

You're probably right, I don't have any hardware supporting
270 degree rotation to test this with.

+	default:
+		rotation = DRM_MODE_ROTATE_0;
+	}
+
+	if (rotation == DRM_MODE_ROTATE_0 || !plane->rotation_property) {
+		fb_helper->rotations |= rotation;
+		return;
+	}
+
+	for (i = 0; i < plane->rotation_property->num_values; i++)
+		valid_mask |= (1ULL << plane->rotation_property->values[i]);

This isn't a good enough check for atomic drivers (and not for gen9+ intel
hw), since we might expose 90° rotations, but it only works if you have
the correct tiling format.

For atomic drivers it'd be really good if we could do a TEST_ONLY commit
first, and if that fails, fall back to sw rotation.

But that poses a bit a chicken&egg with creating the framebuffer (we need
one for the TEST_ONLY), so probably a bit too much more for this. And
afaiui your quirk list only applies to older stuff.

At least add a FIXME meanwhile? In a way we have a FIXME already for
multi-pipe, since we don't try to fall back to fewer pipes if the single
atomic commit failed.

Or maybe just don't use 90/270 hw rotation for now since it seems buggy in
your code anyway.

I was wondering about this (need for special fb layout) myself too, I
agree also given the above comment that it is probably best to only
support 0/180 degree hardware rotation for now, I will do for the next
version (and add a TODO comment).

It'll work on i915 at least, on current hw. Might still be broken on
other, but then that's a larger issue with the fbcon atomic code right
now.


+
+	if (!(rotation & valid_mask)) {
+		fb_helper->rotations |= rotation;
+		return;
+	}
+
+	fb_crtc->rotation = rotation;
+	/* Rotating in hardware, fbcon should not rotate */
+	fb_helper->rotations |= DRM_MODE_ROTATE_0;

Wrong bitopt I think.

No this is intentional, if we've a panel requiring say 90 degree rotation
which we will do in software and another panel (weird example) doing 180
degree rotation in hardware, then we want to or both
DRM_MODE_ROTATE_90 and DRM_MODE_ROTATE_0 into the rotations bitmask
(0 since the hardware rotation requires no sw rotation).
The rotations bitmask is the *combination* of all rotations we need
fbcon to do in software and when that ends up being more then one
rotation we chicken out and just don't do any software rotation,
maybe I should rename rotations to sw_rotations?

A better real world example is a 90 degree rotated panel with
an external monitor, in that case for the panel we hit:

	if (!(rotation & valid_mask)) {
		fb_helper->rotations |= rotation;
		return;
	}

Or-ing in the panel's DRM_MODE_ROTATE_90.

And for the monitor we hit:

	if (rotation == DRM_MODE_ROTATE_0 || !plane->rotation_property) {
		fb_helper->rotations |= rotation;
		return;
	}

Or-ing in the monitors's DRM_MODE_ROTATE_0.

So we end up with 2 bits set in fb_helper->rotations, hitting the
default in the switch case and picking FB_ROTATE_UR, since we cannot
satisfy both rotations in fbcon at the same time.


Or you're doing some really funny control logic by oring in another value
to hit the default case below which doesn't rotate anything. I think that
should be done explicitly, by explicitly setting to rotation to ROTATE_0
instead of this. Same for the check above.

I hope my explanation above explains why I'm or-ing together rotations,
basically I want to detect if we need more then 1 type of software-rotation
in fbcon and in that case bail out and fallback to FB_ROTATE_UR.

Yeah I suspected this is what you're trying to do, but imo it's too clear.
Can't we do an explicit check for this instead of uncommented magic

Erm, my patch contains a big(ish) comment above drm_setup_crtc_rotation which
tries to explain this already.
that takes half an hour to understand? I'm thinking of

if (count_bits(fbb_helper->rotation)) {
	/* conflicting rotation requests on different connnectors, fall
	 * back to unrotated. */

	 fb_helper->rotation == ROTATE_0
}

Or something similar at the end of drm_setup_crtcs (plus maybe doing the
resolve in there too). Right now that logic is split between 2 functions,
and no comment explaining what's going on.

But not sure that's actually going to help with readability.

I was thinking of just changing the code setting the fbcon_rotate_hint
to something like this:

        switch (fb_helper->sw_rotations) {
        case DRM_MODE_ROTATE_0:
                info->fbcon_rotate_hint = FB_ROTATE_UR;
                break;
        case DRM_MODE_ROTATE_90:
                info->fbcon_rotate_hint = FB_ROTATE_CCW;
                break;
        case DRM_MODE_ROTATE_180:
                info->fbcon_rotate_hint = FB_ROTATE_UD;
                break;
        case DRM_MODE_ROTATE_270:
                info->fbcon_rotate_hint = FB_ROTATE_CW;
                break;
        default:
		/*
		 * Multiple bits are set / multiple rotations requested
		 * fbcon cannot handle separate rotation settings per
		 * output, so fallback to unrotated.
		 */
                info->fbcon_rotate_hint = FB_ROTATE_UR;
        }

Would that work for you ?

Regards,

Hans
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