Re: [v3 5/5] drm/msm/disp/dpu1: add PSR support for eDP interface in dpu driver

From: Dmitry Baryshkov
Date: Tue Jun 21 2022 - 15:09:38 EST

On 21/06/2022 13:53, Vinod Polimera wrote:
Enable PSR on eDP interface using drm self-refresh librabry.
This patch uses a trigger from self-refresh library to enter/exit
into PSR, when there are no updates from framework.

Signed-off-by: Kalyan Thota <quic_kalyant@xxxxxxxxxxx>
Signed-off-by: Vinod Polimera <quic_vpolimer@xxxxxxxxxxx>
---
drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 36 ++++++++++++++++++++++++-----
drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 20 +++++++++++++++-
drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 2 +-
3 files changed, 50 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
index b56f777..c6e4f03 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
@@ -18,6 +18,7 @@
#include <drm/drm_probe_helper.h>
#include <drm/drm_rect.h>
#include <drm/drm_vblank.h>
+#include <drm/drm_self_refresh_helper.h>
#include "dpu_kms.h"
#include "dpu_hw_lm.h"
@@ -955,24 +956,39 @@ static void dpu_crtc_disable(struct drm_crtc *crtc,
crtc);
struct dpu_crtc *dpu_crtc = to_dpu_crtc(crtc);
struct dpu_crtc_state *cstate = to_dpu_crtc_state(crtc->state);
- struct drm_encoder *encoder;
+ struct drm_encoder *encoder = NULL;
unsigned long flags;
bool release_bandwidth = false;
DRM_DEBUG_KMS("crtc%d\n", crtc->base.id);
+ if (old_crtc_state->self_refresh_active) {
+ drm_for_each_encoder_mask(encoder, crtc->dev,
+ old_crtc_state->encoder_mask) {
+ dpu_encoder_assign_crtc(encoder, NULL);

I think we should drop dpu_encoder_assign_crtc completely and use your new helpers instead. Having to manually duplicate existing link sounds like a bad idea.

+ }
+ return;
+ }
+
/* Disable/save vblank irq handling */
drm_crtc_vblank_off(crtc);
drm_for_each_encoder_mask(encoder, crtc->dev,
old_crtc_state->encoder_mask) {
- /* in video mode, we hold an extra bandwidth reference
+ /*
+ * in video mode, we hold an extra bandwidth reference

Unrelated to this patch.

* as we cannot drop bandwidth at frame-done if any
* crtc is being used in video mode.
*/
if (dpu_encoder_get_intf_mode(encoder) == INTF_MODE_VIDEO)
release_bandwidth = true;
- dpu_encoder_assign_crtc(encoder, NULL);
+ /*
+ * If disable is triggered during psr active(e.g: screen dim in PSR),
+ * we will need encoder->crtc connection to process the device sleep &
+ * preserve it during psr sequence.
+ */
+ if (!crtc->state->self_refresh_active)
+ dpu_encoder_assign_crtc(encoder, NULL);
}
/* wait for frame_event_done completion */
@@ -1020,7 +1036,9 @@ static void dpu_crtc_enable(struct drm_crtc *crtc,
struct dpu_crtc *dpu_crtc = to_dpu_crtc(crtc);
struct drm_encoder *encoder;
bool request_bandwidth = false;
+ struct drm_crtc_state *old_crtc_state;
+ old_crtc_state = drm_atomic_get_old_crtc_state(state, crtc);
pm_runtime_get_sync(crtc->dev->dev);
DRM_DEBUG_KMS("crtc%d\n", crtc->base.id);
@@ -1042,8 +1060,9 @@ static void dpu_crtc_enable(struct drm_crtc *crtc,
trace_dpu_crtc_enable(DRMID(crtc), true, dpu_crtc);
dpu_crtc->enabled = true;
- drm_for_each_encoder_mask(encoder, crtc->dev, crtc->state->encoder_mask)
- dpu_encoder_assign_crtc(encoder, crtc);
+ if (!old_crtc_state->self_refresh_active)
+ drm_for_each_encoder_mask(encoder, crtc->dev, crtc->state->encoder_mask)
+ dpu_encoder_assign_crtc(encoder, crtc);
/* Enable/restore vblank irq handling */
drm_crtc_vblank_on(crtc);
@@ -1525,7 +1544,7 @@ struct drm_crtc *dpu_crtc_init(struct drm_device *dev, struct drm_plane *plane,
{
struct drm_crtc *crtc = NULL;
struct dpu_crtc *dpu_crtc = NULL;
- int i;
+ int i, ret;
dpu_crtc = kzalloc(sizeof(*dpu_crtc), GFP_KERNEL);
if (!dpu_crtc)
@@ -1562,6 +1581,11 @@ struct drm_crtc *dpu_crtc_init(struct drm_device *dev, struct drm_plane *plane,
/* initialize event handling */
spin_lock_init(&dpu_crtc->event_lock);
+ ret = drm_self_refresh_helper_init(crtc);
+ if (ret)
+ DPU_ERROR("Failed to initialize %s with self-refresh helpers %d\n",
+ crtc->name, ret);
+
DRM_DEBUG_KMS("%s: successfully initialized crtc\n", dpu_crtc->name);
return crtc;
}
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
index cc2809b..234e95d 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
@@ -225,6 +225,11 @@ bool dpu_encoder_is_widebus_enabled(const struct drm_encoder *drm_enc)
return dpu_enc->wide_bus_en;
}
+static inline bool is_self_refresh_active(const struct drm_crtc_state *state)
+{
+ return (state && state->self_refresh_active);
+}
+
static void _dpu_encoder_setup_dither(struct dpu_hw_pingpong *hw_pp, unsigned bpc)
{
struct dpu_hw_dither_cfg dither_cfg = { 0 };
@@ -592,7 +597,8 @@ static int dpu_encoder_virt_atomic_check(
if (drm_atomic_crtc_needs_modeset(crtc_state)) {
dpu_rm_release(global_state, drm_enc);
- if (!crtc_state->active_changed || crtc_state->active)
+ if (!crtc_state->active_changed || crtc_state->active ||
+ crtc_state->self_refresh_active)

This condition should be changed to use enabled rather than active. Quoting KMS documentation: 'The driver must not release any shared resources if active is set to false but enable still true...'

ret = dpu_rm_reserve(&dpu_kms->rm, global_state,
drm_enc, crtc_state, topology);
}
@@ -1171,11 +1177,23 @@ static void dpu_encoder_virt_atomic_disable(struct drm_encoder *drm_enc,
struct drm_atomic_state *state)
{
struct dpu_encoder_virt *dpu_enc = NULL;
+ struct drm_crtc *crtc;
+ struct drm_crtc_state *old_state;
int i = 0;
dpu_enc = to_dpu_encoder_virt(drm_enc);
DPU_DEBUG_ENC(dpu_enc, "\n");
+ crtc = dpu_enc->crtc;
+ old_state = drm_atomic_get_old_crtc_state(state, crtc);
+
+ /*
+ * The encoder disabled already occurred when self refresh mode
+ * was set earlier, in the old_state for the corresponding crtc.
+ */
+ if (drm_enc->encoder_type == DRM_MODE_ENCODER_TMDS && is_self_refresh_active(old_state))
+ return;
+

Why do you need to check the encoder_type?

mutex_lock(&dpu_enc->enc_lock);
dpu_enc->enabled = false;
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
index bce4764..cc0a674 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
@@ -507,7 +507,7 @@ static void dpu_kms_wait_for_commit_done(struct msm_kms *kms,
return;
}
- if (!crtc->state->active) {
+ if (!drm_atomic_crtc_effectively_active(crtc->state)) {
DPU_DEBUG("[crtc:%d] not active\n", crtc->base.id);
return;
}


--
With best wishes
Dmitry