Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [RFC PATCH 2/4] mmc: core: implement enhanced strobe support | From | Shawn Lin <> | Date | Fri, 4 Mar 2016 10:00:52 +0800 |
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Hi Adrian,
On 2016/3/3 21:37, Adrian Hunter wrote: > On 03/03/16 04:36, Shawn Lin wrote: >> Controllers use data strobe line to latch data from devices >> under hs400 mode, but not for cmd line. So from emmc 5.1, JEDEC >> introduces enhanced strobe mode for latching cmd response from >> emmc devices to host controllers. This new feature is optional. > > As I currently understand it, HS400ES does not require tuning. > Consequently you can go straight to HS400ES and do not need to do > HS200 first. If that is the case then more changes are needed. >
That's the case, and it's already in my plan before I going to remove "RFC" prefix. From my experience of developing emmc-device firmware, the only reason we need tuning for HS200 before we switch it into HS400 is that although data-line can be latched by DS but the cmd-line is still in SDR mode when runing in HS400. With hs400-es setuped, tuning and retune stuff is meaningless. ALl the SI should be guranteed by HW design to regulate the PCB payload.
> Also it would be nice if the transfer mode displayed reflected enhanced > strobe e.g.
Great idea! And maybe more thing should be done for core/debugfs.c It seems to big change for init_card, so I need more time to split my step for changing it to make the change will not do any side effect from non-hs400es procedure. :)
Thanks.
> > Currently > > mmc1: new HS400 MMC card at address 0001 > > Change for enhance strobe supported > > mmc1: new HS400ES MMC card at address 0001 > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
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