Re: [PATCH v3] mmc: sdhci-msm: Add pm_runtime and system PM support

From: Ulf Hansson
Date: Fri Sep 23 2016 - 06:07:46 EST


>>>> Is there anything else needed in msm sdhci driver so that the auto
>>>> tuning is taken care of?
>>> I am not familiar with any other than sdhci-esdhc-imx which supports
>>> the SDHCI_TUNING_MODE_3. I may be wrong though.
>>> In the sdhci-esdhc-imx case, enabling of auto tuning seems to be done
>>> in esdhc_post_tuning(), where a vendor specific register
>>> (ESDHC_MIX_CTRL) is being written to. Perhaps something similar in
>>> your case?
>> Thanks Ulf for the comments. Will check this and see if there is
>> something of this sort we have to do to achieve auto tuning.
>> Adding Ritesh who has been posting some SDHCI MSM patches recently in
>> case he knows about this.
> Internally, we don't use this Auto re-tuning and rely on explicit re-tune by
> host driver.
> Question though -
> 1. why do we need to call sdhci_runtime_resume/suspend from
> sdhci_msm_runtime_suspend/resume?
> From what I see is, sdhci_runtime_susend/resume will do reset and re-program
> of host->pwr and host->clk because of which a retune will be required for
> the next command after runtime resume.
> We can *only* disable and enable the clocks in
> sdhci_msm_runtime_suspend/resume?
> Thoughts? With this, I suppose you would not see any issue.

I see.

I assumes that means saving/restoring register context will
automatically handled by some other outer logic, when doing clock

In other words, if the controller has valid tuning values, those will
be re-used and restored when clock ungating happens?

> Though for this issue, since internally also auto retuning is never used, we
> can have this mode disabled. I can once again check with HW team to get more
> details about this mode for MSM controller.
>> Regards,
>> Pramod

Kind regards