Thanks for this Andrei, I have a couple questions:
SDIO - not being DMA does that mean WiFi transfers use a lot of CPU?
And also, do most current SoC share SDIO channels with eMMC or is this limited to mediatek? I know the mt6589 shared this and so under heavy WiFi loads flash performance suffered. Is this the same for the, say, snapdragon 800?
It means that some processor must manually perform memory copies between different device address spaces, although not necessarily (and probably not) the main host CPU. With DMA you can basically just setup buffers that are shared and let the other device stream data in/out.
Actually most sdmmc/sdio controller come with DMA engine. The most inefficient part of sdmmc/sdio is its protocol design(half duplex, frequent controller register access and interrupt design).
Yes, SDIO in past phones are connected through one of the channels on the SoC's eMMC controller. I'm not sure about MediaTek but this shouldn't have caused a bottleneck though.
Hi, Andrei "The BCM4358 was the first such chip to take advantage of this switch", BCM4335 and BCM4339 supported PCIe as well. why do you mention those products (together with BCM4358) as the first time that PCIe became the main interface outside?
Andrei, thanks for an interesting post. The Broadcom press release claims: "Fast mode switch between RSDB and 2x2 MIMO modes". I suppose that this means that RSDB only supports 1x1 mode simultaneous. Was that your understanding from the demo?
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Pissedoffyouth - Monday, March 2, 2015 - link
Thanks for this Andrei, I have a couple questions:SDIO - not being DMA does that mean WiFi transfers use a lot of CPU?
And also, do most current SoC share SDIO channels with eMMC or is this limited to mediatek? I know the mt6589 shared this and so under heavy WiFi loads flash performance suffered. Is this the same for the, say, snapdragon 800?
saratoga4 - Monday, March 2, 2015 - link
It means that some processor must manually perform memory copies between different device address spaces, although not necessarily (and probably not) the main host CPU. With DMA you can basically just setup buffers that are shared and let the other device stream data in/out.g1011999 - Tuesday, March 3, 2015 - link
Actually most sdmmc/sdio controller come with DMA engine. The most inefficient part of sdmmc/sdio is its protocol design(half duplex, frequent controller register access and interrupt design).Andrei Frumusanu - Tuesday, March 3, 2015 - link
Yes, SDIO in past phones are connected through one of the channels on the SoC's eMMC controller. I'm not sure about MediaTek but this shouldn't have caused a bottleneck though.David1972 - Monday, March 9, 2015 - link
Hi, Andrei "The BCM4358 was the first such chip to take advantage of this switch", BCM4335 and BCM4339 supported PCIe as well. why do you mention those products (together with BCM4358) as the first time that PCIe became the main interface outside?Dave
Udo_d - Wednesday, April 15, 2015 - link
Andrei, thanks for an interesting post.The Broadcom press release claims:
"Fast mode switch between RSDB and 2x2 MIMO modes".
I suppose that this means that RSDB only supports 1x1 mode simultaneous.
Was that your understanding from the demo?