Nouveau - Dec 2015 - [RFC PATCH 4/5] subdev/clk: print the base clocks

Hi,

On 05:42 PM - Dec 01 2015, Karol Herbst wrote:
> this is just a nice thing to know and there is no harm in printing them
> ---
>  drm/nouveau/nvkm/subdev/clk/base.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drm/nouveau/nvkm/subdev/clk/base.c
b/drm/nouveau/nvkm/subdev/clk/base.c
> index d731bc3..df9173e 100644
> --- a/drm/nouveau/nvkm/subdev/clk/base.c
> +++ b/drm/nouveau/nvkm/subdev/clk/base.c
> @@ -24,6 +24,7 @@
>  #include "priv.h"
>  
>  #include <subdev/bios.h>
> +#include <subdev/bios/baseclock.h>
>  #include <subdev/bios/boost.h>
>  #include <subdev/bios/cstep.h>
>  #include <subdev/bios/perf.h>
> @@ -562,10 +563,25 @@ int
>  nvkm_clk_ctor(const struct nvkm_clk_func *func, struct nvkm_device
*device,
>  	      int index, bool allow_reclock, struct nvkm_clk *clk)
>  {
> +	struct nvkm_bios *bios;
>  	int ret, idx, arglen;
>  	const char *mode;
> +	struct nvbios_baseclock_header header;
>  
>  	nvkm_subdev_ctor(&nvkm_clk, device, index, 0, &clk->subdev);
> +	bios = device->bios;
> +
> +	if (bios && !nvbios_baseclock_parse(bios, &header)) {
> +		struct nvbios_baseclock_entry base_entry, boost_entry;
> +		if (nvbios_baseclock_get_entry(bios, &header, header.base_entry,
&base_entry))
> +			nvkm_error(&clk->subdev, "couldn't parse base
clock\n");
> +		else if (nvbios_baseclock_get_entry(bios, &header,
header.boost_entry, &boost_entry))
> +			nvkm_error(&clk->subdev, "couldn't parse boost
clock\n");
> +		else
> +			nvkm_info(&clk->subdev, "base: %i MHz, boost: %i
MHz\n",
> +				base_entry.clock_mhz / 2, boost_entry.clock_mhz / 2);
This is probably just me missing some elementary electronic knowledge about
clocks, but why do you divide the clock frequency by two?

Regards,
Pierre
> +	}
> +
>  	clk->func = func;
>  	INIT_LIST_HEAD(&clk->states);
>  	clk->domains = func->domains;
> -- 
> 2.6.3
> 
> _______________________________________________
> Nouveau mailing list
> Nouveau at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/nouveau

> Pierre Moreau <pierre.morrow at free.fr> hat am 2. Dezember 2015 um
02:34
> geschrieben:
> 
> Hi,
> 
> On 05:42 PM - Dec 01 2015, Karol Herbst wrote:
> > this is just a nice thing to know and there is no harm in printing
them
> > ---
> > drm/nouveau/nvkm/subdev/clk/base.c | 16 ++++++++++++++++
> > 1 file changed, 16 insertions(+)
> > 
> > diff --git a/drm/nouveau/nvkm/subdev/clk/base.c
> > b/drm/nouveau/nvkm/subdev/clk/base.c
> > index d731bc3..df9173e 100644
> > --- a/drm/nouveau/nvkm/subdev/clk/base.c
> > +++ b/drm/nouveau/nvkm/subdev/clk/base.c
> > @@ -24,6 +24,7 @@
> > #include "priv.h"
> > 
> > #include <subdev/bios.h>
> > +#include <subdev/bios/baseclock.h>
> > #include <subdev/bios/boost.h>
> > #include <subdev/bios/cstep.h>
> > #include <subdev/bios/perf.h>
> > @@ -562,10 +563,25 @@ int
> > nvkm_clk_ctor(const struct nvkm_clk_func *func, struct nvkm_device
*device,
> > int index, bool allow_reclock, struct nvkm_clk *clk)
> > {
> > + struct nvkm_bios *bios;
> > int ret, idx, arglen;
> > const char *mode;
> > + struct nvbios_baseclock_header header;
> > 
> > nvkm_subdev_ctor(&amp;nvkm_clk, device, index, 0,
&amp;clk->subdev);
> > + bios = device->bios;
> > +
> > + if (bios &amp;&amp; !nvbios_baseclock_parse(bios,
&amp;header)) {
> > + struct nvbios_baseclock_entry base_entry, boost_entry;
> > + if (nvbios_baseclock_get_entry(bios, &amp;header,
header.base_entry,
> > &amp;base_entry))
> > + nvkm_error(&amp;clk->subdev, "couldn't parse base
clock\n");
> > + else if (nvbios_baseclock_get_entry(bios, &amp;header,
header.boost_entry,
> > &amp;boost_entry))
> > + nvkm_error(&amp;clk->subdev, "couldn't parse boost
clock\n");
> > + else
> > + nvkm_info(&amp;clk->subdev, "base: %i MHz, boost: %i
MHz\n",
> > + base_entry.clock_mhz / 2, boost_entry.clock_mhz / 2);
> 
> This is probably just me missing some elementary electronic knowledge about
> clocks, but why do you divide the clock frequency by two?
> 
This is because if the card was sold with 800/850 MHz the table contains
1600/1700. And because I don't want that confusion I stick with the
"halfed"
clocks.
I don't know why they are doubled though or the marketing ones halfed.
> Regards,
> Pierre
> 
> > + }
> > +
> > clk->func = func;
> > INIT_LIST_HEAD(&amp;clk->states);
> > clk->domains = func->domains;
> > -- 
> > 2.6.3
> > 
> > _______________________________________________
> > Nouveau mailing list
> > Nouveau at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/nouveau

On 2 December 2015 at 12:21, Karol Herbst <nouveau at karolherbst.de>
wrote:
>> Pierre Moreau <pierre.morrow at free.fr> hat am 2. Dezember 2015
um 02:34
>> geschrieben:
>>
>> Hi,
>>
>> On 05:42 PM - Dec 01 2015, Karol Herbst wrote:
>> > this is just a nice thing to know and there is no harm in printing
them
>> > ---
>> > drm/nouveau/nvkm/subdev/clk/base.c | 16 ++++++++++++++++
>> > 1 file changed, 16 insertions(+)
>> >
>> > diff --git a/drm/nouveau/nvkm/subdev/clk/base.c
>> > b/drm/nouveau/nvkm/subdev/clk/base.c
>> > index d731bc3..df9173e 100644
>> > --- a/drm/nouveau/nvkm/subdev/clk/base.c
>> > +++ b/drm/nouveau/nvkm/subdev/clk/base.c
>> > @@ -24,6 +24,7 @@
>> > #include "priv.h"
>> >
>> > #include <subdev/bios.h>
>> > +#include <subdev/bios/baseclock.h>
>> > #include <subdev/bios/boost.h>
>> > #include <subdev/bios/cstep.h>
>> > #include <subdev/bios/perf.h>
>> > @@ -562,10 +563,25 @@ int
>> > nvkm_clk_ctor(const struct nvkm_clk_func *func, struct nvkm_device
*device,
>> > int index, bool allow_reclock, struct nvkm_clk *clk)
>> > {
>> > + struct nvkm_bios *bios;
>> > int ret, idx, arglen;
>> > const char *mode;
>> > + struct nvbios_baseclock_header header;
>> >
>> > nvkm_subdev_ctor(&amp;nvkm_clk, device, index, 0,
&amp;clk->subdev);
>> > + bios = device->bios;
>> > +
>> > + if (bios &amp;&amp; !nvbios_baseclock_parse(bios,
&amp;header)) {
>> > + struct nvbios_baseclock_entry base_entry, boost_entry;
>> > + if (nvbios_baseclock_get_entry(bios, &amp;header,
header.base_entry,
>> > &amp;base_entry))
>> > + nvkm_error(&amp;clk->subdev, "couldn't parse
base clock\n");
>> > + else if (nvbios_baseclock_get_entry(bios, &amp;header,
header.boost_entry,
>> > &amp;boost_entry))
>> > + nvkm_error(&amp;clk->subdev, "couldn't parse
boost clock\n");
>> > + else
>> > + nvkm_info(&amp;clk->subdev, "base: %i MHz, boost: %i
MHz\n",
>> > + base_entry.clock_mhz / 2, boost_entry.clock_mhz / 2);
>>
>> This is probably just me missing some elementary electronic knowledge
about
>> clocks, but why do you divide the clock frequency by two?
>>
> This is because if the card was sold with 800/850 MHz the table contains
> 1600/1700. And because I don't want that confusion I stick with the
"halfed"
> clocks.
> I don't know why they are doubled though or the marketing ones halfed.
>
A short (and not 100% accurate) description comes from DDR - double
data rate. I.e. effective = 2x actual clock rate.

In some cases the vbios use(d) to store the actual, while in other
cases the effective rate.

-Emil