[PATCH] drm/stm: support runtime power management

From: Yannick FertrÃ
Date: Mon Jun 03 2019 - 04:36:02 EST

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This patch enables runtime power management (runtime PM) support for
the display controller. pm_runtime_enable() and pm_runtime_disable()
are added during ltdc load and unload respectively.
pm_runtime_get_sync() and pm_runtime_put_sync() are added for ltdc
register access.

Signed-off-by: Yannick FertrÃ <yannick.fertre@xxxxxx>
---
drivers/gpu/drm/stm/drv.c | 43 +++++++++++++++++++++++------
drivers/gpu/drm/stm/ltdc.c | 67 +++++++++++++++++++++++++++++++++++-----------
2 files changed, 86 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/stm/drv.c b/drivers/gpu/drm/stm/drv.c
index 5834ef5..5659572 100644
--- a/drivers/gpu/drm/stm/drv.c
+++ b/drivers/gpu/drm/stm/drv.c
@@ -12,6 +12,7 @@
#include <linux/dma-mapping.h>
#include <linux/module.h>
#include <linux/of_platform.h>
+#include <linux/pm_runtime.h>

#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
@@ -135,14 +136,15 @@ static __maybe_unused int drv_suspend(struct device *dev)
struct ltdc_device *ldev = ddev->dev_private;
struct drm_atomic_state *state;

- drm_kms_helper_poll_disable(ddev);
+ if (WARN_ON(!ldev->suspend_state))
+ return -ENOENT;
+
state = drm_atomic_helper_suspend(ddev);
- if (IS_ERR(state)) {
- drm_kms_helper_poll_enable(ddev);
+ if (IS_ERR(state))
return PTR_ERR(state);
- }
+
ldev->suspend_state = state;
- ltdc_suspend(ddev);
+ pm_runtime_force_suspend(dev);

return 0;
}
@@ -151,16 +153,41 @@ static __maybe_unused int drv_resume(struct device *dev)
{
struct drm_device *ddev = dev_get_drvdata(dev);
struct ltdc_device *ldev = ddev->dev_private;
+ int ret;

- ltdc_resume(ddev);
- drm_atomic_helper_resume(ddev, ldev->suspend_state);
- drm_kms_helper_poll_enable(ddev);
+ pm_runtime_force_resume(dev);
+ ret = drm_atomic_helper_resume(ddev, ldev->suspend_state);
+ if (ret) {
+ pm_runtime_force_suspend(dev);
+ ldev->suspend_state = NULL;
+ return ret;
+ }

return 0;
}

+static __maybe_unused int drv_runtime_suspend(struct device *dev)
+{
+ struct drm_device *ddev = dev_get_drvdata(dev);
+
+ DRM_DEBUG_DRIVER("\n");
+ ltdc_suspend(ddev);
+
+ return 0;
+}
+
+static __maybe_unused int drv_runtime_resume(struct device *dev)
+{
+ struct drm_device *ddev = dev_get_drvdata(dev);
+
+ DRM_DEBUG_DRIVER("\n");
+ return ltdc_resume(ddev);
+}
+
static const struct dev_pm_ops drv_pm_ops = {
SET_SYSTEM_SLEEP_PM_OPS(drv_suspend, drv_resume)
+ SET_RUNTIME_PM_OPS(drv_runtime_suspend,
+ drv_runtime_resume, NULL)
};

static int stm_drm_platform_probe(struct platform_device *pdev)
diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
index ac29890..a40870b 100644
--- a/drivers/gpu/drm/stm/ltdc.c
+++ b/drivers/gpu/drm/stm/ltdc.c
@@ -16,6 +16,7 @@
#include <linux/of_address.h>
#include <linux/of_graph.h>
#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
#include <linux/reset.h>

#include <drm/drm_atomic.h>
@@ -444,6 +445,7 @@ static void ltdc_crtc_atomic_disable(struct drm_crtc *crtc,
struct drm_crtc_state *old_state)
{
struct ltdc_device *ldev = crtc_to_ltdc(crtc);
+ struct drm_device *ddev = crtc->dev;

DRM_DEBUG_DRIVER("\n");

@@ -457,6 +459,8 @@ static void ltdc_crtc_atomic_disable(struct drm_crtc *crtc,

/* immediately commit disable of layers before switching off LTDC */
reg_set(ldev->regs, LTDC_SRCR, SRCR_IMR);
+
+ pm_runtime_put_sync(ddev->dev);
}

#define CLK_TOLERANCE_HZ 50
@@ -505,17 +509,31 @@ static bool ltdc_crtc_mode_fixup(struct drm_crtc *crtc,
struct drm_display_mode *adjusted_mode)
{
struct ltdc_device *ldev = crtc_to_ltdc(crtc);
+ struct drm_device *ddev = crtc->dev;
int rate = mode->clock * 1000;
+ bool runtime_active;
+ int ret;
+
+ runtime_active = pm_runtime_active(ddev->dev);
+
+ if (runtime_active)
+ pm_runtime_put_sync(ddev->dev);

- clk_disable(ldev->pixel_clk);
if (clk_set_rate(ldev->pixel_clk, rate) < 0) {
DRM_ERROR("Cannot set rate (%dHz) for pixel clk\n", rate);
return false;
}
- clk_enable(ldev->pixel_clk);

adjusted_mode->clock = clk_get_rate(ldev->pixel_clk) / 1000;

+ if (runtime_active) {
+ ret = pm_runtime_get_sync(ddev->dev);
+ if (ret) {
+ DRM_ERROR("Failed to fixup mode, cannot get sync\n");
+ return false;
+ }
+ }
+
DRM_DEBUG_DRIVER("requested clock %dkHz, adjusted clock %dkHz\n",
mode->clock, adjusted_mode->clock);

@@ -525,11 +543,21 @@ static bool ltdc_crtc_mode_fixup(struct drm_crtc *crtc,
static void ltdc_crtc_mode_set_nofb(struct drm_crtc *crtc)
{
struct ltdc_device *ldev = crtc_to_ltdc(crtc);
+ struct drm_device *ddev = crtc->dev;
struct drm_display_mode *mode = &crtc->state->adjusted_mode;
struct videomode vm;
u32 hsync, vsync, accum_hbp, accum_vbp, accum_act_w, accum_act_h;
u32 total_width, total_height;
u32 val;
+ int ret;
+
+ if (!pm_runtime_active(ddev->dev)) {
+ ret = pm_runtime_get_sync(ddev->dev);
+ if (ret) {
+ DRM_ERROR("Failed to set mode, cannot get sync\n");
+ return;
+ }
+ }

drm_display_mode_to_videomode(mode, &vm);

@@ -590,6 +618,7 @@ static void ltdc_crtc_atomic_flush(struct drm_crtc *crtc,
struct drm_crtc_state *old_crtc_state)
{
struct ltdc_device *ldev = crtc_to_ltdc(crtc);
+ struct drm_device *ddev = crtc->dev;
struct drm_pending_vblank_event *event = crtc->state->event;

DRM_DEBUG_ATOMIC("\n");
@@ -602,12 +631,12 @@ static void ltdc_crtc_atomic_flush(struct drm_crtc *crtc,
if (event) {
crtc->state->event = NULL;

- spin_lock_irq(&crtc->dev->event_lock);
+ spin_lock_irq(&ddev->event_lock);
if (drm_crtc_vblank_get(crtc) == 0)
drm_crtc_arm_vblank_event(crtc, event);
else
drm_crtc_send_vblank_event(crtc, event);
- spin_unlock_irq(&crtc->dev->event_lock);
+ spin_unlock_irq(&ddev->event_lock);
}
}

@@ -663,15 +692,19 @@ bool ltdc_crtc_scanoutpos(struct drm_device *ddev, unsigned int pipe,
* Computation for the two first cases are identical so we can
* simplify the code and only test if line > vactive_end
*/
- line = reg_read(ldev->regs, LTDC_CPSR) & CPSR_CYPOS;
- vactive_start = reg_read(ldev->regs, LTDC_BPCR) & BPCR_AVBP;
- vactive_end = reg_read(ldev->regs, LTDC_AWCR) & AWCR_AAH;
- vtotal = reg_read(ldev->regs, LTDC_TWCR) & TWCR_TOTALH;
-
- if (line > vactive_end)
- *vpos = line - vtotal - vactive_start;
- else
- *vpos = line - vactive_start;
+ if (pm_runtime_active(ddev->dev)) {
+ line = reg_read(ldev->regs, LTDC_CPSR) & CPSR_CYPOS;
+ vactive_start = reg_read(ldev->regs, LTDC_BPCR) & BPCR_AVBP;
+ vactive_end = reg_read(ldev->regs, LTDC_AWCR) & AWCR_AAH;
+ vtotal = reg_read(ldev->regs, LTDC_TWCR) & TWCR_TOTALH;
+
+ if (line > vactive_end)
+ *vpos = line - vtotal - vactive_start;
+ else
+ *vpos = line - vactive_start;
+ } else {
+ *vpos = 0;
+ }

*hpos = 0;

@@ -1243,8 +1276,11 @@ int ltdc_load(struct drm_device *ddev)
/* Allow usage of vblank without having to call drm_irq_install */
ddev->irq_enabled = 1;

- return 0;
+ clk_disable_unprepare(ldev->pixel_clk);
+
+ pm_runtime_enable(ddev->dev);

+ return 0;
err:
for (i = 0; i < MAX_ENDPOINTS; i++)
drm_panel_bridge_remove(bridge[i]);
@@ -1256,7 +1292,6 @@ int ltdc_load(struct drm_device *ddev)

void ltdc_unload(struct drm_device *ddev)
{
- struct ltdc_device *ldev = ddev->dev_private;
int i;

DRM_DEBUG_DRIVER("\n");
@@ -1264,7 +1299,7 @@ void ltdc_unload(struct drm_device *ddev)
for (i = 0; i < MAX_ENDPOINTS; i++)
drm_of_panel_bridge_remove(ddev->dev->of_node, 0, i);

- clk_disable_unprepare(ldev->pixel_clk);
+ pm_runtime_disable(ddev->dev);
}

MODULE_AUTHOR("Philippe Cornu <philippe.cornu@xxxxxx>");
--
2.7.4

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