Skylake Iris 540 renderer string in i965 (the same as HD 520)

[Ben Widawsky]

On Tue, Mar 29, 2016 at 09:00:14PM +0200, Michal Powalko wrote:
> Dear Ben and Michal,
> dear Ubuntu-bugsquad,
> 
> I have recently bought a new Skylake based NUC with Intel® Core(TM) i5-6260U
> processor and Intel® Iris(TM) graphics 540. I am working on Ubunut 14.04.3
> LTS (kernel 4.2) and waiting for 16.04 (kernel 4.4) to take advantage of
> both CPU (from Linux kernels > 4.3) and GPU full support. The 16.04 beta 2
> is quite "unstable" in terms of Skylake GPU (see e.g. the archlinux source),
> so I tried to find out the walk-around to make it work more stable...
> 
> I have found out Mesa  commit "i965/skl: Update Skylake renderer strings"
> describing the device ID's of different GPU's. In case of my NUC, according
> the ARK' info Iris 540 has the ID of 0x1916, which in Mesa 11.x file has
> associated with HD 520 :( I did some research and found out, that the ID of
> 0x1916 can be used for HD 520 and Iris 540 (see attached screen-shots and
> links below) depending on the CPU :/
> 
> 1. Would it be possible for You to find out the solution to assign the
>    proper GPU name base on ID (Iris 540 in case of i5-6260U) -  maybe
>    using CPU info ?
> 2. Can the wrong name / feature assessment between HD 520 and Iris 540
>    be the source of unstable operation / freeze / crash of the system
>    (system working well but slow with Gallium3Ddriver)?
> 
> I would be really happy to help You providing more information if necessary.
> 
> Sources:
> 
>  * Mesa commit
>    https://cgit.freedesktop.org/mesa/mesa/commit/?h=11.2&id=20e8ee36627f87414440650dcff89990eb70c688
> 
>  * Wiki is saying:  Iris Graphics 540, *GT3e* - 48 execution units with
>    64 MB of eDRAM, up to 806.4 GFLOPS at 1.05 GHz
>    https://en.wikipedia.org/wiki/Intel_HD_and_Iris_Graphics
>    https://en.wikipedia.org/wiki/List_of_Intel_graphics_processing_units
> 
>  * Intel graphics on linux
>    https://wiki.archlinux.org/index.php/intel_graphics
> 
>  * NUC specification
>    http://www.intel.com/content/www/us/en/nuc/nuc-kit-nuc6i5syh.html
> 
>  * Intel Gen9 HD Graphics
>    http://www.anandtech.com/show/9582/intel-skylake-mobile-desktop-launch-architecture-analysis/6
> 
> 
> Best regards from Denmark
> Michal Powalko
> 
> 


Thank you for bringing this to my attention. Summing up there are two products
with the same devid, but different branding.
520: http://ark.intel.com/products/88192/Intel-Core-i7-6600U-Processor-4M-Cache-up-to-3_40-GHz
540: http://ark.intel.com/products/91160/Intel-Core-i5-6260U-Processor-4M-Cache-up-to-2_90-GHz

Let me look into this further, and I will see what we can do. Meanwhile, I would
advise filing a bug upstream on freedesktop.org.


-- 
Ben Widawsky, Intel Open Source Technology Center