AM3356: Supporting eMMC sleep mode with CMD5 command

Takayuki Miyazaki

Part Number: AM3356

Hi Experts,

Customer would like to reduce power consumption as possible because their system is mobile equipment. The eMMC which customer is using complies with JEDEC standard and this eMMC is able to enter Sleep-state with CMD5 command. Therefore, customer is asking AM335x Processor SDK(Version: 06_03_00_106) is supporting eMMC's sleep-mode or not.

According to customer's kernel-code-analysis, they believe Linux SDK is supporting this. I mean, SDK is controlling Sleep-state with CMD5 command as follows. Is customer's understanding correct? Can we have Expert's comments on this, please?

drivers/mmc/core/mmc.c

---------------------------------------------------------------------

static int mmc_sleep(struct mmc_host *host) {

       printk(KERN_INFO ">>> enter mmc_sleep\n");

       struct mmc_command cmd = {};

       struct mmc_card *card = host->card;

       unsigned int timeout_ms = DIV_ROUND_UP(card->ext_csd.sa_timeout, 10000);

       int err;

 

       /* Re-tuning can't be done once the card is deselected */

       mmc_retune_hold(host);

 

       err = mmc_deselect_cards(host);

       if (err)

             goto out_release;

 

       cmd.opcode = MMC_SLEEP_AWAKE;

       . . . . .

}

---------------------------------------------------------------------

mmc.h

-----------------------------------------------------------------------

#define MMC_SLEEP_AWAKE          5   /* ac   [31:16] RCA 15:flg R1b */

-----------------------------------------------------------------------

Best regards,

Miyazaki

over 5 years ago

0 Nick Saulnier over 5 years ago

TI__Guru** 109650 points

Hello Takayuki-san,

I assume this is a follow-up to your post Inquiry about eMMC’s Low Power mode.

Is sleep state not working like the customer was expecting it to?

Regards,

Nick

0 Takayuki Miyazaki over 5 years ago in reply to Nick Saulnier

TI__Genius 10120 points

Hello Nick,

Customer believes sleep-state would be working, however, it is difficult to check it is working actually by scope/waveform. Therefore, customer would like to just confirm Processor SDK is supporting eMMC's sleep-mode for eMMC. I believe so, but, Can we have your Expert’s comments on this, please?

Best regards,

Miyazaki

0 Nick Saulnier over 5 years ago in reply to Takayuki Miyazaki

TI__Guru** 109650 points

Hello Miyazaki,

If it is supported by upstream Linux I would expect it to be supported in the eMMC driver. Let me check with the development team and get back to you. Please ping me if I have not replied in several business days.

Thanks,

Nick

0 Takayuki Miyazaki over 5 years ago in reply to Nick Saulnier

TI__Genius 10120 points

Hello Nick,

Regarding this inquiry about eMMC driver, we'd like to ping you. I'm sorry to rushing your team.

Can we have your Expert's advice/comments on this, please?

Best regards,

Miyazaki

0 Nick Saulnier over 5 years ago in reply to Takayuki Miyazaki

TI__Guru** 109650 points

Hello Miyazaki-san,

Thank you for the ping. I have not heard back from the developers yet, I just reached out again. mmc/host/omap_hsmmc.c has functions omap_hsmmc_suspend & omap_hsmmc_resume, but off the top of my head I'm not sure where the condition for #ifdef CONFIG_PM_SLEEP is set or how it interacts with the larger power management system.

Regards,

Nick

0 Nick Saulnier over 5 years ago in reply to Nick Saulnier

TI__Guru** 109650 points

Ok, CONFIG_PM_SLEEP is defined in .config when kernel power management is enabled.

I would expect that customer could place printk statements in those functions if they wanted to verify that the driver was putting the MMC to sleep and waking it back up. Here is the TI training for debugging embedded Linux.

Regards,

Nick

0 Takayuki Miyazaki over 5 years ago in reply to Nick Saulnier

TI__Genius 10120 points

Hello Nick,

Thank you for your clarification. I shared your advice/comments with customer. I'd like to wait for a while.

Best regards,

Miyazaki

0 Takayuki Miyazaki over 5 years ago in reply to Takayuki Miyazaki

TI__Genius 10120 points

Hi Nick,

Since I did not receive further questions, I'll close this ticket.

Best regards,

Miyazaki

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AM3356: Supporting eMMC sleep mode with CMD5 command