drm/stm: support runtime power management

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 Fertré <yannick.fertre@st.com>
Acked-by: Philippe Cornu <philippe.cornu@st.com>
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1559550722-14091-1-git-send-email-yannick.fertre@st.com

diff --git a/drivers/gpu/drm/stm/drv.c b/drivers/gpu/drm/stm/drv.c
index 5834ef56fbaa72a04e8154043b7f630a63e300fd..5659572151a8ced4866af5c0d7782d9c07de76de 100644 (file)
--- 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 a0c0005e72e1b0010b0cbeae5218c7d8b601b726..2fe6c4a8d91559093d5742bb7c21a11930d41741 100644 (file)
--- 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 @@ err:
 
 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@st.com>");