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drm/vc4: crtc: Keep the previously assigned HVS FIFO

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The HVS FIFOs are currently assigned each time we have an atomic_check
for all the enabled CRTCs.

However, if we are running multiple outputs in parallel and we happen to
disable the first (by index) CRTC, we end up changing the assigned FIFO
of the second CRTC without disabling and reenabling the pixelvalve which
ends up in a stall and eventually a VBLANK timeout.

In order to fix this, we can create a special value for our assigned
channel to mark it as disabled, and if our CRTC already had an assigned
channel in its previous state, we keep on using it.

Fixes: 87ebcd42fb ("drm/vc4: crtc: Assign output to channel automatically")
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Tested-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200923084032.218619-2-maxime@cerno.tech
This commit is contained in:
Maxime Ripard 2020-09-23 10:40:32 +02:00
parent 427c4a0680
commit 8ba0b6d196
No known key found for this signature in database
GPG Key ID: E3EF0D6F671851C5
3 changed files with 19 additions and 6 deletions
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1
drivers/gpu/drm/vc4/vc4_crtc.c
View File

@ -863,6 +863,7 @@ void vc4_crtc_reset(struct drm_crtc *crtc)
return;
}
vc4_crtc_state->assigned_channel = VC4_HVS_CHANNEL_DISABLED;
__drm_atomic_helper_crtc_reset(crtc, &vc4_crtc_state->base);
}

2
drivers/gpu/drm/vc4/vc4_drv.h
View File

@ -532,6 +532,8 @@ struct vc4_crtc_state {
} margins;
};
#define VC4_HVS_CHANNEL_DISABLED ((unsigned int)-1)
static inline struct vc4_crtc_state *
to_vc4_crtc_state(struct drm_crtc_state *crtc_state)
{

22
drivers/gpu/drm/vc4/vc4_kms.c
View File

@ -616,7 +616,7 @@ static int
vc4_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
{
unsigned long unassigned_channels = GENMASK(NUM_CHANNELS - 1, 0);
struct drm_crtc_state *crtc_state;
struct drm_crtc_state *old_crtc_state, *new_crtc_state;
struct drm_crtc *crtc;
int i, ret;
@ -629,6 +629,8 @@ vc4_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
* modified.
*/
list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
struct drm_crtc_state *crtc_state;
if (!crtc->state->enable)
continue;
@ -637,15 +639,23 @@ vc4_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
return PTR_ERR(crtc_state);
}
for_each_new_crtc_in_state(state, crtc, crtc_state, i) {
struct vc4_crtc_state *vc4_crtc_state =
to_vc4_crtc_state(crtc_state);
for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
struct vc4_crtc_state *new_vc4_crtc_state =
to_vc4_crtc_state(new_crtc_state);
struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
unsigned int matching_channels;
if (!crtc_state->enable)
if (old_crtc_state->enable && !new_crtc_state->enable)
new_vc4_crtc_state->assigned_channel = VC4_HVS_CHANNEL_DISABLED;
if (!new_crtc_state->enable)
continue;
if (new_vc4_crtc_state->assigned_channel != VC4_HVS_CHANNEL_DISABLED) {
unassigned_channels &= ~BIT(new_vc4_crtc_state->assigned_channel);
continue;
}
/*
* The problem we have to solve here is that we have
* up to 7 encoders, connected to up to 6 CRTCs.
@ -674,7 +684,7 @@ vc4_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
if (matching_channels) {
unsigned int channel = ffs(matching_channels) - 1;
vc4_crtc_state->assigned_channel = channel;
new_vc4_crtc_state->assigned_channel = channel;
unassigned_channels &= ~BIT(channel);
} else {
return -EINVAL;