Re: [PATCH] drm/stm: support runtime power management

From: Philippe CORNU
Date: Fri Jun 07 2019 - 07:24:19 EST

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Hi Yannick,

Thank you for your patch

Acked-by: Philippe Cornu <philippe.cornu@xxxxxx>

Philippe :-)

On 6/3/19 10:32 AM, Yannick FertrÃ wrote:
> 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>");
>

Next message: Mika Westerberg: "Re: [PATCH 2/2] PCI: PM: Replace pci_dev_keep_suspended() with two functions"
Previous message: Ulf Hansson: "Re: [PATCH 00/18] ARM/ARM64: Support hierarchical CPU arrangement for PSCI"
In reply to: Yannick FertrÃ: "[PATCH] drm/stm: support runtime power management"
Next in thread: Benjamin Gaignard: "Re: [PATCH] drm/stm: support runtime power management"
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