Review Index:

Qualcomm Snapdragon 835 Preview - Semi-custom Kryo 280, Adreno 540, 10nm FinFET

Author: Ryan Shrout
Subject: Processors, Mobile
Manufacturer: Qualcomm

Adreno, Connectivity, Security

The immersion pillar is where Qualcomm talks about performance improvements. The biggest component in this space is the new Adreno 540 GPU. It is based on the same basic design as the Adreno 4x series of GPUs with no drastic changes to the architecture itself. Still, Qualcomm claims SD 835 has a 25% GPU performance advantage over the SD 820. Where does that come from? Again, with some vague comments throughout our meetings, I learned that engineers looked for the primary bottlenecks and addressed them with small tweaks. Z-culling was improved to minimize work on occluded pixels. Draw order independent depth projection was added. Tweaks to the ALUs. Higher order mipmaps and mipmap level swapping.

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Regardless of how it’s done, a 25% increase in rendering capability should directly translate to improved gaming and VR experiences on Snapdragon 835.

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Other changes in the GPU block are on the display and video processing side. The DPU (display processing unit) now supports 10-bit 4K 60 Hz panels and output, wide color gamut (HDR) and a new feature called Q-Sync (think G-Sync for mobile devices). The VPU (video processing unit) can now handle 10-bit 4K HEVC playback and foveated video. HDR10 may not be a big deal for the current generation of phones, and you could debate the usefulness of HDR screens that are 5 inches and smaller, but the ability to output to larger screens, or for Snapdragon SoCs to be used in set-top boxes, makes this a necessary check box in 2017.

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Q-Sync is interesting to me as I have a lot of experience with both NVIDIA G-Sync and AMD FreeSync on the desktop side of gaming. With Q-Sync the displays is refreshed at the same FPS that the GPU is rendering at, helping to remove stutter and jank from the gaming experience. This could be great if properly implemented, but I have questions that are unanswered about how many screens will support it, what the frame rate ranges are, how Qualcomm will handle low frame rate compensation and who is ultimately going to be responsible for the Q-Sync experience.

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The other pillars require a bit more time for me to dive into the technologies that make them up, but are worth mentioning here on launch day. The capture pillar focuses on the new Spectra 180 ISP and its dual 14-bit nature capable of 32MP or dual 16MP camera modules. This ISP allows the Snapdragon 835 to offer hardware accelerated HDR and drastically improved autofocus speed (with an emphasis on low light scenarios).

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Under the connectivity pillar falls the Snapdragon X16 LTE modem, capable of up to Gigabit speeds. It also integrates 802.11ad multi-Gigabit Wi-Fi support (offering up to 4.6 Gbps peak speed) into the platform. Gigabit LTE networks are still in the build-out phase, though both T-Mobile in the US and Telstra in Australia have rollout plans for 2017. The new WCN 3990 Wi-Fi controller as part of Snapdragon 835 enables 802.11ac support with 2x2 MU-MIMO with 50-60% smaller footprint and power consumption than the previous generation.

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Finally, one of the most important pillars: security. The inclusion of the new Haven Security Platform provides hardware-based protection for user authentication and device attestation. By integrating this at the SoC level, Qualcomm can create a secure execution environment for things like a secure camera, secure fingerprint reader, and app/OS integrity checks.

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There is still a lot to learn about Qualcomm’s latest flagship Snapdragon 835 SoC. With access to hardware in the coming weeks and months we should be able to layout the argument for or against it by measuring performance, effective power efficiency, and its ability to excel in workloads like VR and 4K video playback and capture. The Snapdragon 820 created a new landscape in the smartphone market, one where Qualcomm’s claims and partner devices are under more scrutiny. After a course correction with the SD 821, the company needs a homerun with the new Snapdragon 835. The early information looks promising and I am looking forward to evaluating its execution.

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January 3, 2017 | 05:44 PM - Posted by Anonymous (not verified)

"Qualcomm, along with Apple and Samsung, had been the best examples of custom core designs for ARM SoCs"!

No Apple has a true custom core that is a twice as wide order superscalar design than Qualcomm's semi-custom designs or ARM Holdings’ own reference core designs. The Apple Cyclone cores where an in-house design and no one has enough information on the Qualcomm 820 to verify its design as fully in house custom. Apple even beat ARM Holdings itself, the creator of the ARMv8A ISA, in getting a 64 bit custom ARMv8A ISA running micro-architecture to market.

Let’s stop with the just benchmarks and start making these “Custom” ARM based companies to offer the same necessary CPU core data sheets and technical information that the x86 makers do for their respective CPU cores. This lack of properly published custom ARM core specification listings is getting a bit too old now. Look at the core information provided by AMD for Ryzen/older, or Intel for SandyBridge/newer and older and even IBM for Power8/Power9 and ask yourselves what are the custom ARM core makers hiding, are these “custom cores” really custom or are they using mostly ARM holdings’ reference designs and misleading the markets.

Apple’s Cyclone is the last fully custom ARMv8A running Apple CPU core to be detailed and Anand Lal Shimpi was the last reporter outside of a pay wall with the skill set to write a proper custom ARM CPU core review. The Apple Cyclone was in no part by Apple properly explained to the market, it took Anand Lal Shimpi to do that.

Nvidia’s Really Custom Denver cores where properly presented at the Hot Chips Symposium so Nvidia is more like AMD, Intel, and IBM in that regard to not insulting the technically inclined with so much marketing driven drivel in the place of proper white papers that describe in great detail a REAL custom CPU core’s inner workings.

Benchmarks can be gamed, Show me the hardware!!!

There are no Reviews of many, to this day, of the custom ARM cores there are only Previews that remain only that the preview level for lack of proper reporting on the custom ARM CPU core designs!

You can go read Anand Lal Shimpi’s Apple Cyclone reviews and those where real reviews, not this eternal Preview stuff available on tech sites since Anand departed AnandTech!

January 3, 2017 | 10:11 PM - Posted by johnc (not verified)

Well, Anand ended up with a nice, mysterious and cushy job at Apple too.

January 4, 2017 | 09:07 AM - Posted by Anonymous (not verified)

Yes and Apple hired him to shut him up! So Anand had his price! I’m very surprised that Anand did not go on to found his own pay-walled publication but we do have the Linley Group's Microprocessor Report that has been doing what Anand was doing since Anand himself was in diapers.

I do mean more so the Microprocessor Report when it was an independent publication, but it’s still fairly good under the Linley Group’s control, that is when Linley keeps their hands off of the reporting end of what the Microprocessor Report does best!

And Now “AnandTech” is owned by the same media outfit that owns Tom’s hardware! But AnandTech can still do a good article from time to time before the really good reporters are hired up away to the pay-walled professional Trade Journals like the Microprocessor Report and others. There was some particularly good reporting on the ARM Holdings A73 reference design cores and also on the Arm Holdings new Mali/Bifrost GPU micro-architecture and even Tom’s hardware can produce some good articles from time to time also but that is becoming rarer and rarer as time passes.

Currently under a very special Apple NDA, Anand Lal Shimpi is sealed away in carbonite inside a deep underground secret chamber below the under construction new Apple Space Ship Headquarters.

January 4, 2017 | 10:01 AM - Posted by Anonymous (not verified)

Well it looks like I'll eat some crow on the 820/custom bit but Charlie over at S/A is doing a rare for S/A deeper dive into the 835 in a rather long article that he occasionally does. So it's a good read for more information not hidden behind S/A's usual pay-wall!

"Qualcomm opens up a bit more on the 10nm Snapdragon 835 SoC"

January 14, 2017 | 02:19 AM - Posted by anonymous (not verified)

Shilling works better when you're not so obvious about it.

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