| Message ID | Pine.LNX.4.64.1307261214430.22137@axis700.grange (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On 07/26/2013 05:19 AM, Guennadi Liakhovetski wrote: > Currently the cpufreq-cpu0 driver doesn't support Device Tree probing. To > support it we add an OF match table to it. In principle this alone is > enough to get the driver working with DT devices, but then the driver > rewrites the .of_node field of the probed device with a different one, > which isn't clean. To avoid this we use the cpu0 system device for clock > and OPP handling, similar to what the arm_big_little CPUFreq driver does. > This is also less intrusive, since the cpu0 device's .of_node field is > initially NULL, since this isn't a DT device. > > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@gmail.com> > --- > drivers/cpufreq/cpufreq-cpu0.c | 14 +++++++++++--- > 1 files changed, 11 insertions(+), 3 deletions(-) > > diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c > index ad1fde2..d2ad7b8 100644 > --- a/drivers/cpufreq/cpufreq-cpu0.c > +++ b/drivers/cpufreq/cpufreq-cpu0.c > @@ -12,6 +12,7 @@ > #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > > #include <linux/clk.h> > +#include <linux/cpu.h> > #include <linux/cpufreq.h> > #include <linux/err.h> > #include <linux/module.h> > @@ -194,7 +195,7 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev) > goto out_put_parent; > } > > - cpu_dev = &pdev->dev; > + cpu_dev = get_cpu_device(0); > cpu_dev->of_node = np; > > cpu_reg = devm_regulator_get(cpu_dev, "cpu0"); > @@ -289,10 +290,17 @@ static int cpu0_cpufreq_remove(struct platform_device *pdev) > return 0; > } > > +static const struct of_device_id cpu0_cpufreq_of_match[] = { > + {.compatible = "cpufreq-cpu0"}, > + {} > +}; > +MODULE_DEVICE_TABLE(of, cpu0_cpufreq_of_match); > + > static struct platform_driver cpu0_cpufreq_platdrv = { > .driver = { > - .name = "cpufreq-cpu0", > - .owner = THIS_MODULE, > + .name = "cpufreq-cpu0", > + .of_match_table = cpu0_cpufreq_of_match, > + .owner = THIS_MODULE, > }, > .probe = cpu0_cpufreq_probe, > .remove = cpu0_cpufreq_remove, > Did we not go down this approach[1] previously? Could you explain why this path is different now? [1] http://marc.info/?t=136304320700004&r=1&w=2
Hi Nishanth On Fri, 26 Jul 2013, Nishanth Menon wrote: > On 07/26/2013 05:19 AM, Guennadi Liakhovetski wrote: > > Currently the cpufreq-cpu0 driver doesn't support Device Tree probing. To > > support it we add an OF match table to it. In principle this alone is > > enough to get the driver working with DT devices, but then the driver > > rewrites the .of_node field of the probed device with a different one, > > which isn't clean. To avoid this we use the cpu0 system device for clock > > and OPP handling, similar to what the arm_big_little CPUFreq driver does. > > This is also less intrusive, since the cpu0 device's .of_node field is > > initially NULL, since this isn't a DT device. > > > > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@gmail.com> > > --- > > drivers/cpufreq/cpufreq-cpu0.c | 14 +++++++++++--- > > 1 files changed, 11 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c > > index ad1fde2..d2ad7b8 100644 > > --- a/drivers/cpufreq/cpufreq-cpu0.c > > +++ b/drivers/cpufreq/cpufreq-cpu0.c > > @@ -12,6 +12,7 @@ > > #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > > > > #include <linux/clk.h> > > +#include <linux/cpu.h> > > #include <linux/cpufreq.h> > > #include <linux/err.h> > > #include <linux/module.h> > > @@ -194,7 +195,7 @@ static int cpu0_cpufreq_probe(struct platform_device > > *pdev) > > goto out_put_parent; > > } > > > > - cpu_dev = &pdev->dev; > > + cpu_dev = get_cpu_device(0); > > cpu_dev->of_node = np; > > > > cpu_reg = devm_regulator_get(cpu_dev, "cpu0"); > > @@ -289,10 +290,17 @@ static int cpu0_cpufreq_remove(struct platform_device > > *pdev) > > return 0; > > } > > > > +static const struct of_device_id cpu0_cpufreq_of_match[] = { > > + {.compatible = "cpufreq-cpu0"}, > > + {} > > +}; > > +MODULE_DEVICE_TABLE(of, cpu0_cpufreq_of_match); > > + > > static struct platform_driver cpu0_cpufreq_platdrv = { > > .driver = { > > - .name = "cpufreq-cpu0", > > - .owner = THIS_MODULE, > > + .name = "cpufreq-cpu0", > > + .of_match_table = cpu0_cpufreq_of_match, > > + .owner = THIS_MODULE, > > }, > > .probe = cpu0_cpufreq_probe, > > .remove = cpu0_cpufreq_remove, > > > Did we not go down this approach[1] previously? Could you explain why this > path is different now? Yes, you're right, I forgot about that discussion, sorry. But my motivation was the following: yes, I'm aware, that the DT should only describe real hardware _devices_ and hardware _properties_. But this patch - just like your original patch - don't add a pseudo _device_ or _property_, but a compatibility string. So, to me it was like "a class of all systems, where the CPU performance can be scaled using one power supply and one clock. Isn't this a hardware feature? We already have CPU nodes in DT, this would be just (an additional) compatibility string to them? I'll be happy to drop this patch and revive yours, if we manage to agree upon the scope. Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 07/26/2013 07:43 AM, Guennadi Liakhovetski wrote: > Hi Nishanth > > On Fri, 26 Jul 2013, Nishanth Menon wrote: > >> On 07/26/2013 05:19 AM, Guennadi Liakhovetski wrote: >>> Currently the cpufreq-cpu0 driver doesn't support Device Tree probing. To >>> support it we add an OF match table to it. In principle this alone is >>> enough to get the driver working with DT devices, but then the driver >>> rewrites the .of_node field of the probed device with a different one, >>> which isn't clean. To avoid this we use the cpu0 system device for clock >>> and OPP handling, similar to what the arm_big_little CPUFreq driver does. >>> This is also less intrusive, since the cpu0 device's .of_node field is >>> initially NULL, since this isn't a DT device. >>> >>> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@gmail.com> >>> --- >>> drivers/cpufreq/cpufreq-cpu0.c | 14 +++++++++++--- >>> 1 files changed, 11 insertions(+), 3 deletions(-) >>> >>> diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c >>> index ad1fde2..d2ad7b8 100644 >>> --- a/drivers/cpufreq/cpufreq-cpu0.c >>> +++ b/drivers/cpufreq/cpufreq-cpu0.c >>> @@ -12,6 +12,7 @@ >>> #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt >>> >>> #include <linux/clk.h> >>> +#include <linux/cpu.h> >>> #include <linux/cpufreq.h> >>> #include <linux/err.h> >>> #include <linux/module.h> >>> @@ -194,7 +195,7 @@ static int cpu0_cpufreq_probe(struct platform_device >>> *pdev) >>> goto out_put_parent; >>> } >>> >>> - cpu_dev = &pdev->dev; >>> + cpu_dev = get_cpu_device(0); >>> cpu_dev->of_node = np; >>> >>> cpu_reg = devm_regulator_get(cpu_dev, "cpu0"); >>> @@ -289,10 +290,17 @@ static int cpu0_cpufreq_remove(struct platform_device >>> *pdev) >>> return 0; >>> } >>> >>> +static const struct of_device_id cpu0_cpufreq_of_match[] = { >>> + {.compatible = "cpufreq-cpu0"}, >>> + {} >>> +}; >>> +MODULE_DEVICE_TABLE(of, cpu0_cpufreq_of_match); >>> + >>> static struct platform_driver cpu0_cpufreq_platdrv = { >>> .driver = { >>> - .name = "cpufreq-cpu0", >>> - .owner = THIS_MODULE, >>> + .name = "cpufreq-cpu0", >>> + .of_match_table = cpu0_cpufreq_of_match, >>> + .owner = THIS_MODULE, >>> }, >>> .probe = cpu0_cpufreq_probe, >>> .remove = cpu0_cpufreq_remove, >>> >> Did we not go down this approach[1] previously? Could you explain why this >> path is different now? > > Yes, you're right, I forgot about that discussion, sorry. But my > motivation was the following: yes, I'm aware, that the DT should only > describe real hardware _devices_ and hardware _properties_. But this patch > - just like your original patch - don't add a pseudo _device_ or > _property_, but a compatibility string. So, to me it was like "a class of > all systems, where the CPU performance can be scaled using one power > supply and one clock. Isn't this a hardware feature? We already have CPU The definition of the hardware (CPU) behavior - which is performance indicator, would be an operating performance point (OPP), no? we have already modelled that in dts - in fact Mike has a better approach that is maturing. As far as I am concerned, a generic device(including processing) which does not have the deep linkage to kernel behavior should be managed by devfreq, cpufreq has linkage to core scheduler and PM behavior, and could be arguably stand alone on its own - though it could be argued that devfreq could be made as a superset of which cpufreq functionality is just one part of it. > nodes in DT, this would be just (an additional) compatibility string to > them? I'll be happy to drop this patch and revive yours, if we manage to > agree upon the scope. As far as I am concerned, the original argument Shawn made[1] is convincing enough for me. Will probably look at Viresh and others to see if there is a change in opinion. [1] http://marc.info/?l=devicetree&m=137435418742097&w=2
On 26 July 2013 18:44, Nishanth Menon <nm@ti.com> wrote: > As far as I am concerned, the original argument Shawn made[1] is convincing > enough for me. > > Will probably look at Viresh and others to see if there is a change in > opinion. I would say that the earlier comments "a real hardware device is required for a node to be present in DT" still stands and so this patch doesn't introduce anything new. @Rob: What do you think about getting a DT node for probing cpufreq driver? We surely need some way without declaring a platform device to get driver probed.. Or if we can put this information in the cpu node, which we don't have to replicate in all cpus.. -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 29 Jul 2013, Viresh Kumar wrote: > On 26 July 2013 18:44, Nishanth Menon <nm@ti.com> wrote: > > As far as I am concerned, the original argument Shawn made[1] is convincing > > enough for me. > > > > Will probably look at Viresh and others to see if there is a change in > > opinion. > > I would say that the earlier comments "a real hardware device is required > for a node to be present in DT" still stands Of course. > and so this patch doesn't introduce anything new. I wasn't proposing to add a new DT node, I was only proposing to add a compatibility line to an existing node, that doesn't create a device normally so far. > @Rob: What do you think about getting a DT node for probing cpufreq > driver? We surely need some way without declaring a platform device > to get driver probed.. > > Or if we can put this information in the cpu node, which we don't have > to replicate in all cpus.. Yes, that was the idea. Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c index ad1fde2..d2ad7b8 100644 --- a/drivers/cpufreq/cpufreq-cpu0.c +++ b/drivers/cpufreq/cpufreq-cpu0.c @@ -12,6 +12,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/clk.h> +#include <linux/cpu.h> #include <linux/cpufreq.h> #include <linux/err.h> #include <linux/module.h> @@ -194,7 +195,7 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev) goto out_put_parent; } - cpu_dev = &pdev->dev; + cpu_dev = get_cpu_device(0); cpu_dev->of_node = np; cpu_reg = devm_regulator_get(cpu_dev, "cpu0"); @@ -289,10 +290,17 @@ static int cpu0_cpufreq_remove(struct platform_device *pdev) return 0; } +static const struct of_device_id cpu0_cpufreq_of_match[] = { + {.compatible = "cpufreq-cpu0"}, + {} +}; +MODULE_DEVICE_TABLE(of, cpu0_cpufreq_of_match); + static struct platform_driver cpu0_cpufreq_platdrv = { .driver = { - .name = "cpufreq-cpu0", - .owner = THIS_MODULE, + .name = "cpufreq-cpu0", + .of_match_table = cpu0_cpufreq_of_match, + .owner = THIS_MODULE, }, .probe = cpu0_cpufreq_probe, .remove = cpu0_cpufreq_remove,
Currently the cpufreq-cpu0 driver doesn't support Device Tree probing. To support it we add an OF match table to it. In principle this alone is enough to get the driver working with DT devices, but then the driver rewrites the .of_node field of the probed device with a different one, which isn't clean. To avoid this we use the cpu0 system device for clock and OPP handling, similar to what the arm_big_little CPUFreq driver does. This is also less intrusive, since the cpu0 device's .of_node field is initially NULL, since this isn't a DT device. Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@gmail.com> --- drivers/cpufreq/cpufreq-cpu0.c | 14 +++++++++++--- 1 files changed, 11 insertions(+), 3 deletions(-)