eMMC tuning issue on Odroid C2 and a possible solution

[Heiner Kallweit]

Am 12.10.2017 um 22:05 schrieb Jerome Brunet:
> On Thu, 2017-10-12 at 21:49 +0200, Heiner Kallweit wrote:
>>> The result of the tuning does not depends on starting point, so I don't
>>> really
>>> understand how it would significantly change things.
>>>
>>
>> I think it depends on the tx phase starting point.
>>
> 
> If the result of the tuning is not independent of the starting, instead of just
> telling me, it is fairly easy for you to give actual result, like I asked you:
> 

With hs200 at 200 and tx phase starting point 0 I get the following with no further CRC errors.

[    0.726572] meson-gx-mmc d0074000.mmc: d0074000.mmc#rx phase/delay tunning...
[    0.728664] hctosys: unable to open rtc device (rtc0)
[    0.728827] USB_OTG_PWR: disabling
[    0.728831] TFLASH_VDD: disabling
[    0.728833] TF_IO: disabling
[    0.753183] Waiting for root device /dev/mmcblk0p1...
[    0.754352] meson-gx-mmc d0074000.mmc: success with phase: 270
[    0.758386] meson-gx-mmc d0074000.mmc: d0074000.mmc#tx phase/delay tunning...
[    0.768050] meson-gx-mmc d0074000.mmc: success with phase: 120
[    0.771235] meson-gx-mmc d0074000.mmc: d0074000.mmc#rx phase/delay tunning...
[    0.780902] meson-gx-mmc d0074000.mmc: success with phase: 0
[    0.784036] mmc0: new HS200 MMC card at address 0001
[    0.789090] mmcblk0: mmc0:0001 DJNB4R 116 GiB
[    0.793328] mmcblk0boot0: mmc0:0001 DJNB4R partition 1 4.00 MiB
[    0.799198] mmcblk0boot1: mmc0:0001 DJNB4R partition 2 4.00 MiB
[    0.805048] mmcblk0rpmb: mmc0:0001 DJNB4R partition 3 4.00 MiB, chardev (249:0)
[    0.812799] mmcblk0: response CRC error sending r/w cmd command, card status 0x900
[    0.819727] meson-gx-mmc d0074000.mmc: d0074000.mmc#tx phase/delay tunning...
[    0.827007] meson-gx-mmc d0074000.mmc: success with phase: 210
[    0.832559] meson-gx-mmc d0074000.mmc: d0074000.mmc#rx phase/delay tunning...
[    0.839848] meson-gx-mmc d0074000.mmc: success with phase: 0


>>> Ok, starting from Rx:0 Tx:270 then tuning gives you Tx:300 Rx:90
>>> And what different did it gives you starting Rx:0/Tx:0 ?
> 
> And if the result are indeed vastly different, let's debug and get a real
> explanation.
> 
>> Tuning does:
>> rx phase tuning
>> tx phase tuning
>> rx phase tuning
>>
>> Result of each step depends on result of previous step.
> 
> Again, we don't agree. 
> 
>> So also the initial
>> rx phase tuning result depends on the starting point of tx phase.
> 
> The first Rx tuning is there only to get a sane starting point for the tx tuning
> ,as explained in the code. This is the reason why is not done when re-tuning.
> 
> 
>