[v3,015/105] drm/vc4: hvs: Boost the core clock during modeset
diff mbox series

Message ID 1aaadf9a5176591c891622cb00b0c50f42e569dc.1590594512.git-series.maxime@cerno.tech
State New
Headers show
Series
  • drm/vc4: Support BCM2711 Display Pipeline
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Commit Message

Maxime Ripard May 27, 2020, 3:47 p.m. UTC
In order to prevent timeouts and stalls in the pipeline, the core clock
needs to be maxed at 500MHz during a modeset on the BCM2711.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
 drivers/gpu/drm/vc4/vc4_drv.h |  2 ++
 drivers/gpu/drm/vc4/vc4_hvs.c |  9 +++++++++
 drivers/gpu/drm/vc4/vc4_kms.c |  7 +++++++
 3 files changed, 18 insertions(+)

Comments

Maxime Ripard June 2, 2020, 12:52 p.m. UTC | #1
Hi Eric,

On Wed, May 27, 2020 at 09:33:44AM -0700, Eric Anholt wrote:
> On Wed, May 27, 2020 at 8:49 AM Maxime Ripard <maxime@cerno.tech> wrote:
> >
> > In order to prevent timeouts and stalls in the pipeline, the core clock
> > needs to be maxed at 500MHz during a modeset on the BCM2711.
> 
> Like, the whole system's core clock?

Yep, unfortunately...

> How is it reasonable for some device driver to crank the system's core
> clock up and back down to some fixed-in-the-driver frequency? Sounds
> like you need some sort of opp thing here.

That frequency is the minimum rate of that clock. However, since other
devices have similar requirements (unicam in particular) with different
minimum requirements, we will switch to setting a minimum rate instead
of enforcing a particular rate, so that patch would be essentially
s/clk_set_rate/clk_set_min_rate/.

Would that work for you?

> 
> Patch 13,14 r-b.

Thanks!
Maxime
Eric Anholt June 2, 2020, 5:52 p.m. UTC | #2
On Tue, Jun 2, 2020 at 5:52 AM Maxime Ripard <maxime@cerno.tech> wrote:
>
> Hi Eric,
>
> On Wed, May 27, 2020 at 09:33:44AM -0700, Eric Anholt wrote:
> > On Wed, May 27, 2020 at 8:49 AM Maxime Ripard <maxime@cerno.tech> wrote:
> > >
> > > In order to prevent timeouts and stalls in the pipeline, the core clock
> > > needs to be maxed at 500MHz during a modeset on the BCM2711.
> >
> > Like, the whole system's core clock?
>
> Yep, unfortunately...
>
> > How is it reasonable for some device driver to crank the system's core
> > clock up and back down to some fixed-in-the-driver frequency? Sounds
> > like you need some sort of opp thing here.
>
> That frequency is the minimum rate of that clock. However, since other
> devices have similar requirements (unicam in particular) with different
> minimum requirements, we will switch to setting a minimum rate instead
> of enforcing a particular rate, so that patch would be essentially
> s/clk_set_rate/clk_set_min_rate/.

clk_set_min_rate makes a lot more sense to me.  r-b with that obvious
change. Thanks!

Patch
diff mbox series

diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
index 1e226454c9a6..9b57ea2ba93f 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.h
+++ b/drivers/gpu/drm/vc4/vc4_drv.h
@@ -323,6 +323,8 @@  struct vc4_hvs {
 	void __iomem *regs;
 	u32 __iomem *dlist;
 
+	struct clk *core_clk;
+
 	/* Memory manager for CRTCs to allocate space in the display
 	 * list.  Units are dwords.
 	 */
diff --git a/drivers/gpu/drm/vc4/vc4_hvs.c b/drivers/gpu/drm/vc4/vc4_hvs.c
index 0fe4758de03a..f4942667355b 100644
--- a/drivers/gpu/drm/vc4/vc4_hvs.c
+++ b/drivers/gpu/drm/vc4/vc4_hvs.c
@@ -19,6 +19,7 @@ 
  * each CRTC.
  */
 
+#include <linux/clk.h>
 #include <linux/component.h>
 #include <linux/platform_device.h>
 
@@ -241,6 +242,14 @@  static int vc4_hvs_bind(struct device *dev, struct device *master, void *data)
 	hvs->regset.regs = hvs_regs;
 	hvs->regset.nregs = ARRAY_SIZE(hvs_regs);
 
+	if (hvs->hvs5) {
+		hvs->core_clk = devm_clk_get(&pdev->dev, NULL);
+		if (IS_ERR(hvs->core_clk)) {
+			dev_err(&pdev->dev, "Couldn't get core clock\n");
+			return PTR_ERR(hvs->core_clk);
+		}
+	}
+
 	if (!hvs->hvs5)
 		hvs->dlist = hvs->regs + SCALER_DLIST_START;
 	else
diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
index 9417e45d981f..29b75b60d858 100644
--- a/drivers/gpu/drm/vc4/vc4_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -11,6 +11,8 @@ 
  * crtc, HDMI encoder).
  */
 
+#include <linux/clk.h>
+
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_crtc.h>
@@ -149,6 +151,7 @@  vc4_atomic_complete_commit(struct drm_atomic_state *state)
 {
 	struct drm_device *dev = state->dev;
 	struct vc4_dev *vc4 = to_vc4_dev(dev);
+	struct vc4_hvs *hvs = vc4->hvs;
 	struct vc4_crtc *vc4_crtc;
 	int i;
 
@@ -160,6 +163,8 @@  vc4_atomic_complete_commit(struct drm_atomic_state *state)
 		vc4_hvs_mask_underrun(dev, vc4_crtc->channel);
 	}
 
+	clk_set_rate(hvs->core_clk, 500000000);
+
 	drm_atomic_helper_wait_for_fences(dev, state, false);
 
 	drm_atomic_helper_wait_for_dependencies(state);
@@ -182,6 +187,8 @@  vc4_atomic_complete_commit(struct drm_atomic_state *state)
 
 	drm_atomic_helper_commit_cleanup_done(state);
 
+	clk_set_rate(hvs->core_clk, 200000000);
+
 	drm_atomic_state_put(state);
 
 	up(&vc4->async_modeset);