AM620-Q1: Concept Clarification For MMC SW Tuning Algorithm

Gibbs Shih

Expert 6440 points

Part Number: AM620-Q1

Tool/software:

Hi, Dear Expert

Here are some concept clarification for MMC SW Tuning Algorithm.

After reading MMC SW Tuning Algorithm & driver code studying, Few question as below.

Ref.https://www.ti.com/lit/an/spract9a/spract9a.pdf?ts=1758591962293&ref_url=https%253A%252F%252Fwww.google.com%252F

(1) I saw "MMC SW Tuning algorithm code" which is implemented in sdhci_am654 linux driver, Does it mean "MMC SW Tuning" auto execution in period of cycle after linux booting?

(2) Base on item (1), if the answer is yes, what's the trigger event for "auto MMC SW Tuning" ?

(3) What's each measure unit for each ratio in 32 slots?

(4) Base on the field "ITAPDLYSEL" in SS_PHY_CTRL_4_REG, Does this value between 0~31 FOR ITAPDLYSEL

Many Thanks

Gibbs

11 months ago

0 Prashant Shivhare 11 months ago

TI__Guru* 87551 points

Hello,

1,2) The tuning is primarily done at the time of the eMMC initialization. The function is bound to the platform structure here (https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/drivers/mmc/host/sdhci_am654.c#n658_) by which this tuning function is called whenever the Kernel MMC driver attempts to execute the tuning.

3,4) Those 32 slots corresponds to the ITAPDLYSEL values.

Regards,

Prashant

0 Gibbs Shih 11 months ago in reply to Prashant Shivhare

TI__Expert 6440 points

Hi, Prashant

Thanks you replies.

I have some one question base on your replies.

your mention,

>> whenever the Kernel MMC driver attempts to execute the tuning.

May I know when does MMC driver attempts to execute the tuning?

Does it control by user?

Thank You,

Gibbs

0 Prashant Shivhare 11 months ago in reply to Gibbs Shih

TI__Guru* 87551 points

Hello,

Gibbs Shih said:
May I know when does MMC driver attempts to execute the tuning?

It is part of the standard eMMC initialization sequence. The tuning is performed at the end of this initialization sequence.

Regards,

Prashant

0 Gibbs Shih 11 months ago in reply to Prashant Shivhare

TI__Expert 6440 points

Thanks. Prashant

I hope I do not miss your meaning, this is conclusion what I learn from this post

Base on our default SW setting, eMMC tuning algorithm only execute one time after eMMC initialization.

Tuning algorithm do not period execution during (Linux) system operation even environment temperature variant.

Thank You Very Much

Gibbs

+1 Prashant Shivhare 11 months ago in reply to Gibbs Shih

TI__Guru* 87551 points

Hello,

Gibbs Shih said:
Tuning algorithm do not period execution during (Linux) system operation even environment temperature variant.

It's not exactly period execution. The Kernel does retuning on detecting errors like the CQE, CRC at runtime.

https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/drivers/mmc/core/core.c#n496

Regards,

Prashant

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AM620-Q1: Concept Clarification For MMC SW Tuning Algorithm