Re: [RFC v2 1/1] drm/lima: Add optional devfreq support

On Sat, Dec 28, 2019 at 1:37 AM Martin Blumenstingl martin.blumenstingl@googlemail.com wrote:

Most platforms with a Mali-400 or Mali-450 GPU also have support for changing the GPU clock frequency. Add devfreq support so the GPU clock rate is updated based on the actual GPU usage when the "operating-points-v2" property is present in the board.dts.

The actual devfreq code is taken from panfrost_devfreq.c and modified so it matches what the lima hardware needs:

• a call to dev_pm_opp_set_clkname() during initialization because there are two clocks on Mali-4x0 IPs. "core" is the one that actually clocks the GPU so we need to control it using devfreq.
• locking when reading or writing the devfreq statistics because (unlike than panfrost) we have multiple PP and GP IRQs which may finish jobs concurrently.

Signed-off-by: Martin Blumenstingl martin.blumenstingl@googlemail.com

drivers/gpu/drm/lima/Kconfig | 1 + drivers/gpu/drm/lima/Makefile | 3 +- drivers/gpu/drm/lima/lima_devfreq.c | 183 ++++++++++++++++++++++++++++ drivers/gpu/drm/lima/lima_devfreq.h | 15 +++ drivers/gpu/drm/lima/lima_device.c | 4 + drivers/gpu/drm/lima/lima_device.h | 17 +++ drivers/gpu/drm/lima/lima_drv.c | 14 ++- drivers/gpu/drm/lima/lima_sched.c | 7 ++ drivers/gpu/drm/lima/lima_sched.h | 3 + 9 files changed, 244 insertions(+), 3 deletions(-) create mode 100644 drivers/gpu/drm/lima/lima_devfreq.c create mode 100644 drivers/gpu/drm/lima/lima_devfreq.h

diff --git a/drivers/gpu/drm/lima/Kconfig b/drivers/gpu/drm/lima/Kconfig index 571dc369a7e9..cdd24b68b5d4 100644 --- a/drivers/gpu/drm/lima/Kconfig +++ b/drivers/gpu/drm/lima/Kconfig @@ -10,5 +10,6 @@ config DRM_LIMA depends on OF select DRM_SCHED select DRM_GEM_SHMEM_HELPER

•   select PM_DEVFREQ
    help
      DRM driver for ARM Mali 400/450 GPUs.
  

diff --git a/drivers/gpu/drm/lima/Makefile b/drivers/gpu/drm/lima/Makefile index a85444b0a1d4..5e5c29875e9c 100644 --- a/drivers/gpu/drm/lima/Makefile +++ b/drivers/gpu/drm/lima/Makefile @@ -14,6 +14,7 @@ lima-y := \ lima_sched.o \ lima_ctx.o \ lima_dlbu.o \

•   lima_bcast.o
  

•   lima_bcast.o \
  

•   lima_devfreq.o
  
  

obj-$(CONFIG_DRM_LIMA) += lima.o diff --git a/drivers/gpu/drm/lima/lima_devfreq.c b/drivers/gpu/drm/lima/lima_devfreq.c new file mode 100644 index 000000000000..a5fd6b8faa77 --- /dev/null +++ b/drivers/gpu/drm/lima/lima_devfreq.c @@ -0,0 +1,183 @@ +// SPDX-License-Identifier: GPL-2.0 +/*

• • Copyright 2019 Martin Blumenstingl martin.blumenstingl@googlemail.com
• • Based on panfrost_devfreq.c:
• • Copyright 2019 Collabora ltd.
• */

+#include <linux/clk.h> +#include <linux/devfreq.h> +#include <linux/devfreq_cooling.h> +#include <linux/device.h> +#include <linux/platform_device.h> +#include <linux/pm_opp.h>

+#include "lima_device.h" +#include "lima_devfreq.h"

+static void lima_devfreq_update_utilization(struct lima_device *ldev) +{

•   unsigned long irqflags;
  

•   ktime_t now, last;
  

•   if (!ldev->devfreq.devfreq)
  

•           return;
  

•   spin_lock_irqsave(&ldev->devfreq.lock, irqflags);
  

•   now = ktime_get();
  

•   last = ldev->devfreq.time_last_update;
  

•   if (atomic_read(&ldev->devfreq.busy_count) > 0)
  

•           ldev->devfreq.busy_time += ktime_sub(now, last);
  

•   else
  

•           ldev->devfreq.idle_time += ktime_sub(now, last);
  

•   ldev->devfreq.time_last_update = now;
  

•   spin_unlock_irqrestore(&ldev->devfreq.lock, irqflags);
  

+}

+static int lima_devfreq_target(struct device *dev, unsigned long *freq,

•                          u32 flags)
  

+{

•   struct dev_pm_opp *opp;
  

•   int err;
  

•   opp = devfreq_recommended_opp(dev, freq, flags);
  

•   if (IS_ERR(opp))
  

•           return PTR_ERR(opp);
  

•   dev_pm_opp_put(opp);
  

•   err = dev_pm_opp_set_rate(dev, *freq);
  

•   if (err)
  

•           return err;
  

•   return 0;
  

+}

+static void lima_devfreq_reset(struct lima_device *ldev) +{

•   unsigned long irqflags;
  

•   spin_lock_irqsave(&ldev->devfreq.lock, irqflags);
  

•   ldev->devfreq.busy_time = 0;
  

•   ldev->devfreq.idle_time = 0;
  

•   ldev->devfreq.time_last_update = ktime_get();
  

•   spin_unlock_irqrestore(&ldev->devfreq.lock, irqflags);
  

+}

+static int lima_devfreq_get_dev_status(struct device *dev,

•                                  struct devfreq_dev_status *status)
  

+{

•   struct lima_device *ldev = dev_get_drvdata(dev);
  

•   unsigned long irqflags;
  

•   lima_devfreq_update_utilization(ldev);
  

•   status->current_frequency = clk_get_rate(ldev->clk_gpu);
  

•   spin_lock_irqsave(&ldev->devfreq.lock, irqflags);
  

•   status->total_time = ktime_to_ns(ktime_add(ldev->devfreq.busy_time,
  

•                                              ldev->devfreq.idle_time));
  

•   status->busy_time = ktime_to_ns(ldev->devfreq.busy_time);
  

•   spin_unlock_irqrestore(&ldev->devfreq.lock, irqflags);
  

•   lima_devfreq_reset(ldev);
  

•   dev_dbg(ldev->dev, "busy %lu total %lu %lu %% freq %lu MHz\n",
  

•           status->busy_time, status->total_time,
  

•           status->busy_time / (status->total_time / 100),
  

•           status->current_frequency / 1000 / 1000);
  

•   return 0;
  

+}

+static struct devfreq_dev_profile lima_devfreq_profile = {

•   .polling_ms = 50, /* ~3 frames */
  

•   .target = lima_devfreq_target,
  

•   .get_dev_status = lima_devfreq_get_dev_status,
  

+};

+int lima_devfreq_init(struct lima_device *ldev) +{

•   struct thermal_cooling_device *cooling;
  

•   struct device *dev = &ldev->pdev->dev;
  

•   struct devfreq *devfreq;
  

•   struct dev_pm_opp *opp;
  

•   unsigned long cur_freq;
  

•   int ret;
  

•   spin_lock_init(&ldev->devfreq.lock);
  

•   ldev->devfreq.opp_table = dev_pm_opp_set_clkname(dev, "core");
  

•   if (IS_ERR(ldev->devfreq.opp_table))
  

•           return PTR_ERR(ldev->devfreq.opp_table);
  

•   ret = dev_pm_opp_of_add_table(dev);
  

•   if (ret == -ENODEV) /* Optional, continue without devfreq */
  

•           return 0;
  

•   else if (ret)
  

•           return ret;
  

•   lima_devfreq_reset(ldev);
  

•   cur_freq = clk_get_rate(ldev->clk_gpu);
  

•   opp = devfreq_recommended_opp(dev, &cur_freq, 0);
  

•   if (IS_ERR(opp))
  

•           return PTR_ERR(opp);
  

•   lima_devfreq_profile.initial_freq = cur_freq;
  

•   dev_pm_opp_put(opp);
  

•   devfreq = devm_devfreq_add_device(dev, &lima_devfreq_profile,
  

•                                     DEVFREQ_GOV_SIMPLE_ONDEMAND, NULL);
  

•   if (IS_ERR(devfreq)) {
  

•           dev_err(dev, "Couldn't initialize GPU devfreq\n");
  

•           dev_pm_opp_of_remove_table(dev);
  

•           return PTR_ERR(devfreq);
  

•   }
  

•   ldev->devfreq.devfreq = devfreq;
  

•   cooling = of_devfreq_cooling_register(dev->of_node, devfreq);
  

•   if (IS_ERR(cooling))
  

•           dev_info(dev, "Failed to register cooling device\n");
  

•   else
  

•           ldev->devfreq.cooling = cooling;
  

•   return 0;
  

+}

+void lima_devfreq_fini(struct lima_device *ldev) +{

•   if (ldev->devfreq.cooling)
  

•           devfreq_cooling_unregister(ldev->devfreq.cooling);
  

•   if (ldev->devfreq.opp_table) {
  

•           dev_pm_opp_put_clkname(ldev->devfreq.opp_table);
  

•           ldev->devfreq.opp_table = NULL;
  

•   }
  

•   dev_pm_opp_of_remove_table(&ldev->pdev->dev);
  

+}

+void lima_devfreq_record_busy(struct lima_device *ldev) +{

•   lima_devfreq_update_utilization(ldev);
  

•   atomic_inc(&ldev->devfreq.busy_count);
  

+}

+void lima_devfreq_record_idle(struct lima_device *ldev) +{

•   int count;
  

•   lima_devfreq_update_utilization(ldev);
  

•   count = atomic_dec_if_positive(&ldev->devfreq.busy_count);
  

•   WARN_ON(count < 0);
  

+} diff --git a/drivers/gpu/drm/lima/lima_devfreq.h b/drivers/gpu/drm/lima/lima_devfreq.h new file mode 100644 index 000000000000..fe4f8a437033 --- /dev/null +++ b/drivers/gpu/drm/lima/lima_devfreq.h @@ -0,0 +1,15 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright 2019 Martin Blumenstingl martin.blumenstingl@googlemail.com */

+#ifndef __LIMA_DEVFREQ_H__ +#define __LIMA_DEVFREQ_H__

+struct lima_device;

+int lima_devfreq_init(struct lima_device *ldev); +void lima_devfreq_fini(struct lima_device *ldev);

+void lima_devfreq_record_busy(struct lima_device *ldev); +void lima_devfreq_record_idle(struct lima_device *ldev);

+#endif diff --git a/drivers/gpu/drm/lima/lima_device.c b/drivers/gpu/drm/lima/lima_device.c index 19829b543024..7f1f7a1c03e5 100644 --- a/drivers/gpu/drm/lima/lima_device.c +++ b/drivers/gpu/drm/lima/lima_device.c @@ -214,6 +214,8 @@ static int lima_init_gp_pipe(struct lima_device *dev) struct lima_sched_pipe *pipe = dev->pipe + lima_pipe_gp; int err;

•   pipe->ldev = dev;
  

•   err = lima_sched_pipe_init(pipe, "gp");
    if (err)
            return err;
  

@@ -244,6 +246,8 @@ static int lima_init_pp_pipe(struct lima_device *dev) struct lima_sched_pipe *pipe = dev->pipe + lima_pipe_pp; int err, i;

•   pipe->ldev = dev;
  

•   err = lima_sched_pipe_init(pipe, "pp");
    if (err)
            return err;
  

diff --git a/drivers/gpu/drm/lima/lima_device.h b/drivers/gpu/drm/lima/lima_device.h index 31158d86271c..26f0efdd17f1 100644 --- a/drivers/gpu/drm/lima/lima_device.h +++ b/drivers/gpu/drm/lima/lima_device.h @@ -5,6 +5,7 @@ #define __LIMA_DEVICE_H__

#include <drm/drm_device.h> +#include <linux/atomic.h> #include <linux/delay.h>

#include "lima_sched.h" @@ -94,6 +95,22 @@ struct lima_device {

    u32 *dlbu_cpu;
    dma_addr_t dlbu_dma;

•   struct {
  

•           struct devfreq *devfreq;
  

•           struct opp_table *opp_table;
  

•           struct thermal_cooling_device *cooling;
  

•           ktime_t busy_time;
  

•           ktime_t idle_time;
  

•           ktime_t time_last_update;
  

•           atomic_t busy_count;
  

•           /*
  

•            * Protect busy_time, idle_time and time_last_update because
  

•            * these can be updated concurrently - for example by the GP
  

•            * and PP interrupts.
  

•            */
  

•           spinlock_t lock;
  

•   } devfreq;
  

};

static inline struct lima_device * diff --git a/drivers/gpu/drm/lima/lima_drv.c b/drivers/gpu/drm/lima/lima_drv.c index 124efe4fa97b..b64b1777f220 100644 --- a/drivers/gpu/drm/lima/lima_drv.c +++ b/drivers/gpu/drm/lima/lima_drv.c @@ -10,6 +10,7 @@ #include <drm/drm_prime.h> #include <drm/lima_drm.h>

+#include "lima_devfreq.h" #include "lima_drv.h" #include "lima_gem.h" #include "lima_vm.h" @@ -296,18 +297,26 @@ static int lima_pdev_probe(struct platform_device *pdev) if (err) goto err_out1;

•   err = lima_devfreq_init(ldev);
  

•   if (err) {
  

•           dev_err(&pdev->dev, "Fatal error during devfreq init\n");
  

•           goto err_out2;
  

•   }
  

•   /*
     * Register the DRM device with the core and the connectors with
     * sysfs.
     */
    err = drm_dev_register(ddev, 0);
    if (err < 0)
  

•           goto err_out2;
  

•           goto err_out3;
  
    return 0;
  
  

-err_out2: +err_out3: lima_device_fini(ldev); +err_out2:

•   lima_devfreq_fini(ldev);
  

err_out1: drm_dev_put(ddev); err_out0: @@ -321,6 +330,7 @@ static int lima_pdev_remove(struct platform_device *pdev) struct drm_device *ddev = ldev->ddev;

    drm_dev_unregister(ddev);

•   lima_devfreq_fini(ldev);
    lima_device_fini(ldev);
    drm_dev_put(ddev);
    lima_sched_slab_fini();
  

diff --git a/drivers/gpu/drm/lima/lima_sched.c b/drivers/gpu/drm/lima/lima_sched.c index f522c5f99729..851c496a168b 100644 --- a/drivers/gpu/drm/lima/lima_sched.c +++ b/drivers/gpu/drm/lima/lima_sched.c @@ -5,6 +5,7 @@ #include <linux/slab.h> #include <linux/xarray.h>

+#include "lima_devfreq.h" #include "lima_drv.h" #include "lima_sched.h" #include "lima_vm.h" @@ -213,6 +214,8 @@ static struct dma_fence *lima_sched_run_job(struct drm_sched_job *job) */ ret = dma_fence_get(task->fence);

•   lima_devfreq_record_busy(pipe->ldev);
  

•   pipe->current_task = task;
  
    /* this is needed for MMU to work correctly, otherwise GP/PP
  

@@ -280,6 +283,8 @@ static void lima_sched_handle_error_task(struct lima_sched_pipe *pipe, pipe->current_vm = NULL; pipe->current_task = NULL;

•   lima_devfreq_record_idle(pipe->ldev);
  

•   drm_sched_resubmit_jobs(&pipe->base);
    drm_sched_start(&pipe->base, true);
  

} @@ -348,6 +353,8 @@ void lima_sched_pipe_fini(struct lima_sched_pipe *pipe)

void lima_sched_pipe_task_done(struct lima_sched_pipe *pipe) {

•   lima_devfreq_record_idle(pipe->ldev);
  

This should be moved to the else {} part of the following code. As you have added the save idle record to the lima_sched_handle_error_task which is just the if {} part of the following code, so no need to call it twice for error tasks. BTW. lima_sched_handle_error_task is also used for timeout tasks, so add idle record in it is fine.

Regards, Qiang

•   if (pipe->error)
            schedule_work(&pipe->error_work);
    else {
  

diff --git a/drivers/gpu/drm/lima/lima_sched.h b/drivers/gpu/drm/lima/lima_sched.h index 928af91c1118..9ae7df7d7fbb 100644 --- a/drivers/gpu/drm/lima/lima_sched.h +++ b/drivers/gpu/drm/lima/lima_sched.h @@ -6,6 +6,7 @@

#include <drm/gpu_scheduler.h>

+struct lima_device; struct lima_vm;

struct lima_sched_task { @@ -41,6 +42,8 @@ struct lima_sched_pipe { u32 fence_seqno; spinlock_t fence_lock;

•   struct lima_device *ldev;
  

•   struct lima_sched_task *current_task;
    struct lima_vm *current_vm;
  
  

-- 2.24.1