[RFC v1 0/1] drm: lima: devfreq and cooling device support

[RFC v1 0/1] drm: lima: devfreq and cooling device support

[Martin Blumenstingl]

This is my attempt at adding devfreq (and cooling device) support to
the lima driver.
I didn't have much time to do in-depth testing. However, I'm sending
this out early because there are many SoCs with Mali-400/450 GPU so
I want to avoid duplicating the work with somebody else.

The code is derived from panfrost_devfreq.c which is why I kept the
Collabora copyright in lima_devfreq.c. Please let me know if I should
drop this or how I can make it more clear that I "borrowed" the code
from panfrost.

I am seeking comments in two general areas:
- regarding the integration into the existing lima code
- for the actual devfreq code (I had to adapt the panfrost code
  slightly, because lima uses a bus and a GPU/core clock)

My own TODO list includes "more" testing on various Amlogic SoCs.
So far I have tested this on Meson8b and Meson8m2 (which both have a
GPU OPP table defined). However, I still need to test this on a GXL
board (which is currently missing the GPU OPP table).


Martin Blumenstingl (1):
  drm/lima: Add optional devfreq support

 drivers/gpu/drm/lima/Kconfig        |   1 +
 drivers/gpu/drm/lima/Makefile       |   3 +-
 drivers/gpu/drm/lima/lima_devfreq.c | 162 ++++++++++++++++++++++++++++
 drivers/gpu/drm/lima/lima_devfreq.h |  15 +++
 drivers/gpu/drm/lima/lima_device.c  |   4 +
 drivers/gpu/drm/lima/lima_device.h  |  11 ++
 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, 217 insertions(+), 3 deletions(-)
 create mode 100644 drivers/gpu/drm/lima/lima_devfreq.c
 create mode 100644 drivers/gpu/drm/lima/lima_devfreq.h

-- 
2.24.1


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[RFC v1 1/1] drm/lima: Add optional devfreq support

[Martin Blumenstingl]

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.

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 | 162 ++++++++++++++++++++++++++++
 drivers/gpu/drm/lima/lima_devfreq.h |  15 +++
 drivers/gpu/drm/lima/lima_device.c  |   4 +
 drivers/gpu/drm/lima/lima_device.h  |  11 ++
 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, 217 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..9cefce6352db
--- /dev/null
+++ b/drivers/gpu/drm/lima/lima_devfreq.c
@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright 2019 Collabora ltd. */
+/* Copyright 2019 Martin Blumenstingl <martin.blumenstingl@googlemail.com> */
+#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)
+{
+	ktime_t now;
+	ktime_t last;
+
+	if (!ldev->devfreq.devfreq)
+		return;
+
+	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;
+}
+
+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)
+{
+	ldev->devfreq.busy_time = 0;
+	ldev->devfreq.idle_time = 0;
+	ldev->devfreq.time_last_update = ktime_get();
+}
+
+static int lima_devfreq_get_dev_status(struct device *dev,
+				       struct devfreq_dev_status *status)
+{
+	struct lima_device *ldev = dev_get_drvdata(dev);
+
+	lima_devfreq_update_utilization(ldev);
+
+	status->current_frequency = clk_get_rate(ldev->clk_gpu);
+	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);
+
+	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;
+
+	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..9a3ab7e3169c 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 +95,16 @@ 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;
+	} 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);
+
 	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


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Re: [RFC v1 0/1] drm: lima: devfreq and cooling device support

[Qiang Yu]

Thanks for adding this.

As the license, it's up to you, I think it's OK for now.

For the code, I think you may need some lock to protect the time records as
there are two kernel threads gp/pp will try to mark GPU busy and several
interrupts try to mark GPU idle.

Regards,
Qiang


On Mon, Dec 16, 2019 at 5:12 AM Martin Blumenstingl
<martin.blumenstingl@googlemail.com> wrote:
>
> This is my attempt at adding devfreq (and cooling device) support to
> the lima driver.
> I didn't have much time to do in-depth testing. However, I'm sending
> this out early because there are many SoCs with Mali-400/450 GPU so
> I want to avoid duplicating the work with somebody else.
>
> The code is derived from panfrost_devfreq.c which is why I kept the
> Collabora copyright in lima_devfreq.c. Please let me know if I should
> drop this or how I can make it more clear that I "borrowed" the code
> from panfrost.
>
> I am seeking comments in two general areas:
> - regarding the integration into the existing lima code
> - for the actual devfreq code (I had to adapt the panfrost code
>   slightly, because lima uses a bus and a GPU/core clock)
>
> My own TODO list includes "more" testing on various Amlogic SoCs.
> So far I have tested this on Meson8b and Meson8m2 (which both have a
> GPU OPP table defined). However, I still need to test this on a GXL
> board (which is currently missing the GPU OPP table).
>
>
> Martin Blumenstingl (1):
>   drm/lima: Add optional devfreq support
>
>  drivers/gpu/drm/lima/Kconfig        |   1 +
>  drivers/gpu/drm/lima/Makefile       |   3 +-
>  drivers/gpu/drm/lima/lima_devfreq.c | 162 ++++++++++++++++++++++++++++
>  drivers/gpu/drm/lima/lima_devfreq.h |  15 +++
>  drivers/gpu/drm/lima/lima_device.c  |   4 +
>  drivers/gpu/drm/lima/lima_device.h  |  11 ++
>  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, 217 insertions(+), 3 deletions(-)
>  create mode 100644 drivers/gpu/drm/lima/lima_devfreq.c
>  create mode 100644 drivers/gpu/drm/lima/lima_devfreq.h
>
> --
> 2.24.1
>

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Re: [RFC v1 0/1] drm: lima: devfreq and cooling device support

[Chen-Yu Tsai]

On Mon, Dec 16, 2019 at 5:12 AM Martin Blumenstingl
<martin.blumenstingl@googlemail.com> wrote:
>
> This is my attempt at adding devfreq (and cooling device) support to
> the lima driver.
> I didn't have much time to do in-depth testing. However, I'm sending
> this out early because there are many SoCs with Mali-400/450 GPU so
> I want to avoid duplicating the work with somebody else.
>
> The code is derived from panfrost_devfreq.c which is why I kept the
> Collabora copyright in lima_devfreq.c. Please let me know if I should
> drop this or how I can make it more clear that I "borrowed" the code
> from panfrost.

I think it's more common to have separate copyright notices. First you
have yours, then a second paragraph stating the code is derived from
foo, and then attach the copyright statements for foo.

ChenYu

> I am seeking comments in two general areas:
> - regarding the integration into the existing lima code
> - for the actual devfreq code (I had to adapt the panfrost code
>   slightly, because lima uses a bus and a GPU/core clock)
>
> My own TODO list includes "more" testing on various Amlogic SoCs.
> So far I have tested this on Meson8b and Meson8m2 (which both have a
> GPU OPP table defined). However, I still need to test this on a GXL
> board (which is currently missing the GPU OPP table).
>
>
> Martin Blumenstingl (1):
>   drm/lima: Add optional devfreq support
>
>  drivers/gpu/drm/lima/Kconfig        |   1 +
>  drivers/gpu/drm/lima/Makefile       |   3 +-
>  drivers/gpu/drm/lima/lima_devfreq.c | 162 ++++++++++++++++++++++++++++
>  drivers/gpu/drm/lima/lima_devfreq.h |  15 +++
>  drivers/gpu/drm/lima/lima_device.c  |   4 +
>  drivers/gpu/drm/lima/lima_device.h  |  11 ++
>  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, 217 insertions(+), 3 deletions(-)
>  create mode 100644 drivers/gpu/drm/lima/lima_devfreq.c
>  create mode 100644 drivers/gpu/drm/lima/lima_devfreq.h
>
> --
> 2.24.1
>

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Re: [RFC v1 0/1] drm: lima: devfreq and cooling device support

[Alyssa Rosenzweig]

[-- Attachment #1.1: Type: text/plain, Size: 2009 bytes --]

If so much code is being duplicated over, I'm wondering if it makes
sense for us to move some of the common devfreq code to core DRM
helpers?

On Sun, Dec 15, 2019 at 10:12:22PM +0100, Martin Blumenstingl wrote:
> This is my attempt at adding devfreq (and cooling device) support to
> the lima driver.
> I didn't have much time to do in-depth testing. However, I'm sending
> this out early because there are many SoCs with Mali-400/450 GPU so
> I want to avoid duplicating the work with somebody else.
> 
> The code is derived from panfrost_devfreq.c which is why I kept the
> Collabora copyright in lima_devfreq.c. Please let me know if I should
> drop this or how I can make it more clear that I "borrowed" the code
> from panfrost.
> 
> I am seeking comments in two general areas:
> - regarding the integration into the existing lima code
> - for the actual devfreq code (I had to adapt the panfrost code
>   slightly, because lima uses a bus and a GPU/core clock)
> 
> My own TODO list includes "more" testing on various Amlogic SoCs.
> So far I have tested this on Meson8b and Meson8m2 (which both have a
> GPU OPP table defined). However, I still need to test this on a GXL
> board (which is currently missing the GPU OPP table).
> 
> 
> Martin Blumenstingl (1):
>   drm/lima: Add optional devfreq support
> 
>  drivers/gpu/drm/lima/Kconfig        |   1 +
>  drivers/gpu/drm/lima/Makefile       |   3 +-
>  drivers/gpu/drm/lima/lima_devfreq.c | 162 ++++++++++++++++++++++++++++
>  drivers/gpu/drm/lima/lima_devfreq.h |  15 +++
>  drivers/gpu/drm/lima/lima_device.c  |   4 +
>  drivers/gpu/drm/lima/lima_device.h  |  11 ++
>  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, 217 insertions(+), 3 deletions(-)
>  create mode 100644 drivers/gpu/drm/lima/lima_devfreq.c
>  create mode 100644 drivers/gpu/drm/lima/lima_devfreq.h
> 
> -- 
> 2.24.1
> 

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Re: [RFC v1 0/1] drm: lima: devfreq and cooling device support

[Martin Blumenstingl]

On Mon, Dec 16, 2019 at 3:51 AM Qiang Yu <yuq825@gmail.com> wrote:
[...]
> For the code, I think you may need some lock to protect the time records as
> there are two kernel threads gp/pp will try to mark GPU busy and several
> interrupts try to mark GPU idle.
good catch, thank you for this!
I assume the reason is that the panfrost GPUs are using a "unified"
architecture, while the ones supported by lima don't

I'll add locking so I don't run into trouble.


Thank you!
Martin

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Re: [RFC v1 0/1] drm: lima: devfreq and cooling device support

[Martin Blumenstingl]

On Mon, Dec 16, 2019 at 4:03 AM Chen-Yu Tsai <wens@csie.org> wrote:
>
> On Mon, Dec 16, 2019 at 5:12 AM Martin Blumenstingl
> <martin.blumenstingl@googlemail.com> wrote:
> >
> > This is my attempt at adding devfreq (and cooling device) support to
> > the lima driver.
> > I didn't have much time to do in-depth testing. However, I'm sending
> > this out early because there are many SoCs with Mali-400/450 GPU so
> > I want to avoid duplicating the work with somebody else.
> >
> > The code is derived from panfrost_devfreq.c which is why I kept the
> > Collabora copyright in lima_devfreq.c. Please let me know if I should
> > drop this or how I can make it more clear that I "borrowed" the code
> > from panfrost.
>
> I think it's more common to have separate copyright notices. First you
> have yours, then a second paragraph stating the code is derived from
> foo, and then attach the copyright statements for foo.
thank you for the hint!
I found other examples that do it like this, so I'll update it.


Martin

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Re: [RFC v1 0/1] drm: lima: devfreq and cooling device support

[Martin Blumenstingl]

Hi Alyssa,

On Mon, Dec 16, 2019 at 4:48 PM Alyssa Rosenzweig
<alyssa.rosenzweig@collabora.com> wrote:
>
> If so much code is being duplicated over, I'm wondering if it makes
> sense for us to move some of the common devfreq code to core DRM
> helpers?
if you have any recommendation where to put it then please let me know
(I am not familiar with the DRM subsystem at all)

my initial idea was that the devfreq logic needs the same information
that the scheduler needs (whether we're submitting something to be
executed, there was a timeout, ...).
however, looking at drivers/gpu/drm/scheduler/ this seems pretty
stand-alone so I'm not sure it should go there
also the Mali-4x0 GPUs have some "PMU" which *may* be used instead of
polling the statistics internally
so this is where I realize that with my current knowledge I don't know
enough about lima, panfrost, DRM or the devfreq subsystem to get a
good idea where to put the code.


Martin

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Re: [Lima] [RFC v1 0/1] drm: lima: devfreq and cooling device support

[Icenowy Zheng]

于 2019年12月24日 GMT+08:00 下午7:28:41, Martin Blumenstingl <martin.blumenstingl@googlemail.com> 写到:
>Hi Alyssa,
>
>On Mon, Dec 16, 2019 at 4:48 PM Alyssa Rosenzweig
><alyssa.rosenzweig@collabora.com> wrote:
>>
>> If so much code is being duplicated over, I'm wondering if it makes
>> sense for us to move some of the common devfreq code to core DRM
>> helpers?
>if you have any recommendation where to put it then please let me know
>(I am not familiar with the DRM subsystem at all)
>
>my initial idea was that the devfreq logic needs the same information
>that the scheduler needs (whether we're submitting something to be
>executed, there was a timeout, ...).
>however, looking at drivers/gpu/drm/scheduler/ this seems pretty
>stand-alone so I'm not sure it should go there
>also the Mali-4x0 GPUs have some "PMU" which *may* be used instead of

It's optional. We cannot promise its existance on a given
hardware, and I heard that at least on Allwinner H5 Mali PMU
is broken.

>polling the statistics internally
>so this is where I realize that with my current knowledge I don't know
>enough about lima, panfrost, DRM or the devfreq subsystem to get a
>good idea where to put the code.
>
>
>Martin
>_______________________________________________
>lima mailing list
>lima@lists.freedesktop.org
>https://lists.freedesktop.org/mailman/listinfo/lima

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