[Intel-gfx] intel_gpu_top missing clocks
Ben Widawsky
ben at bwidawsk.net
Thu Jun 19 23:33:07 CEST 2014
On Thu, Jun 19, 2014 at 09:33:44PM +0100, Bragg, Robert wrote:
> On Thu, Jun 19, 2014 at 3:10 PM, Chris Healy <[1]cphealy at gmail.com>
> wrote:
>
> Hi Robert,
> This information is helpful. I am able to query the frequencies as
> you mentioned. My primary interest though is in getting support added
> to intel_gpu_top. It seems to me that intel_gpu_top has been coded to
> support providing clock frequency data for a subset of Intel GPUs and
> that the mobile Ivy Bridge GT2 chipset is not supported. Would you
> agree with this?
>
> That looks right, yep.
intel_gpu_top was designed and developed before we had variable GPU
frequencies and before we had either the sysfs or debugfs interace.
> Â
>
> If so, I'd like to fix this but don't know where to look for the bit
> descriptions for the necessary registers. Can you point me to the
> appropriate document?
>
> I'm afraid it looks like that the i915_debugfs.c code may be the best
> reference a.t.m; though maybe someone who's worked on that code (not
> me) can give you a better answer.
> That said though; it could make sense to update intel_gpu_top to query
> debugfs for this information anyway; considering that it's more up to
> date and that way the logic doesn't need to be duplicated. For example
> if you take a look at overlay/gpu-freq.c in the intel_gpu_tools repo it
> looks like there's already some precedent for doing just that. It also
> looks like the utility code in overlay/debugfs.c can be used to make
> sure debugfs is mounted.
> Sorry I couldn't point you at good documentation for this; but
> hopefully that's still of some help to you.
Please do not use debugfs. Generally this is not the interface to write
a tool against. The sysfs interface is a stable interface, and that
should always be used. tests/pm_rps.c already loads and reads/writes
this interface. Copy that code to print_clock_info () with the
appropriate if (have_sysfs(...)) or whatever you want.
BTW pm_rps has gotten very complex in the last few months. I would
recommend using the git history to find the initial commit for this
task.
> --
> Regards,
> Robert
>
> Regards,
> Chris
>
> On Tue, Jun 17, 2014 at 7:43 PM, Bragg, Robert
> <[2]robert.bragg at intel.com> wrote:
>
> Hi Chris,
> You can query the nominal and maximum frequency of your GPU via
> debugfs, in case that is good enough for your needs. Depending on what
> kernel version you have you can try to cat
> /sys/kernel/debug/dri/0/i915_cur_delayinfo or with more recent
> versions, /sys/kernel/debug/dri/0/i915_frequency_info
> If you are curious about more details then it may be best to look at
> the drm driver code in
> drivers/gpu/drm/i915/i915_debugfs.c:i915_frequency_info().
> --
> Regards,
> Robert
> On Wed, Jun 18, 2014 at 1:55 AM, He, Shuang <[3]shuang.he at intel.com>
> wrote:
>
> Hi, Chris
>
> Â Â Â Â Â Â Â Â Letâs put you to the correct Mailing list for this
> topic first
>
> Â
>
> Thanks
>
> Â Â Â Â Â Â Â Â --Shuang
>
> From: Chris Healy [mailto:[4]cphealy at gmail.com]
> Sent: Wednesday, June 18, 2014 1:15 AM
> To: Eric Anholt; He, Shuang
> Subject: intel_gpu_top missing clocks
>
> Â
>
> Eric, Shuang,
>
> I couldn't find an appropriate mailing list to report this on, so I'm
> mailing the two of you as you've both touched the clock code in
> intel_gpu_top.
>
> I'm running an Ivy Bridge Mobile chipset and trying to use
> intel_gpu_top and intel_stepping to see the GPU clock frequencies. In
> both cases, the clocks are "unknown".
> When I look at the code, it seems that there's just no code path to
> handle this devid, though I'm not sure as I'm not very good at
> understanding code. I see in intel_chipset.h that device id 0x0166 =
> PCI_CHIP_IVYBRIDGE_M_GT2 and that none of the "if's" in
> print_clock_info ultimately point to this device type.
>
> Do either of you know why this would be? Is it just a case of coding
> for the majority of chipset configurations?
>
> If it's just the case of it not yet being handled, I'd be open to
> trying to add support for it if you could point me to the necessary
> chip documentation.
>
> Regards,
> Chris
>
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>
> References
>
> 1. mailto:cphealy at gmail.com
> 2. mailto:robert.bragg at intel.com
> 3. mailto:shuang.he at intel.com
> 4. mailto:cphealy at gmail.com
> 5. mailto:Intel-gfx at lists.freedesktop.org
> 6. http://lists.freedesktop.org/mailman/listinfo/intel-gfx
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--
Ben Widawsky, Intel Open Source Technology Center
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