Re: intel_gpu_top missing clocks

["Bragg, Robert" <robert.bragg@xxxxxxxxx>]

On Thu, Jun 19, 2014 at 3:10 PM, Chris Healy <cphealy@xxxxxxxxx> 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.
 

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.

--

Regards,

Robert

Regards,

Chris

On Tue, Jun 17, 2014 at 7:43 PM, Bragg, Robert <robert.bragg@xxxxxxxxx> 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 <shuang.he@xxxxxxxxx> wrote:

Hi, Chris

         Let’s put you to the correct Mailing list for this topic first

 

Thanks

         --Shuang

From: Chris Healy [mailto:cphealy@xxxxxxxxx]
Sent: Wednesday, June 18, 2014 1:15 AM
To: Eric Anholt; He, Shuang
Subject: intel_gpu_top missing clocks

 

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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