Hi
On 2016年09月01日 12:20, Doug Anderson wrote:
Hi,
On Wed, Aug 31, 2016 at 7:29 PM, Ziyuan Xu <xzy.xu@xxxxxxxxxxxxxx> wrote:
This is fine to pick up _only_ if you don't care about suspend/resume.
If you care about suspend/resume then someone needs to first write a
patch that will re-init all "corecfg" values after power is turned on.
Do you mean corecfg_clockmultiplier and corecfg_baseclkfreq, if yes, we
don't need to strore/re-init it after resume.
corecfg_clockmultiplier is only used to fetch host->clk_mul, and
host->clk_mul has been a fixed value at run-time, unless driver unbind.
The same as corecfg_clockmultiplier, corecfg_baseclkfreq is used to check
the xin_clk at probe time, we don't reference it at run-time.
BTW, I have tested suspend/resume on rk3399 prior to this sumbit, eMMC works
fine.
I guess I don't actually know how the corecfg_clockmultiplier and
corecfg_baseclkfreq fields are actually used, but I presume that they
actually do something useful and aren't used to just communicate back
to software?
Take corecfg_clockmultiplier as example.
1. sdhci driver fetch host->clk_mul from corecfg_clockmultiplier
2. mmc->f_min and mmc->f_max are calculated via host->clk_mul, they're
used for further initialization.
3. if the corecfg_clockmultiplier is incorrect, sdhci will use improper
frequency to play.
I think we don't need to store it due to it's a fixed value at run-time,
even if it is reset after a power cycle, the above will not be changed
via software, except for dirver unbind .
I know that:
1. If I don't pick this patch and I suspend/resume,
corecfg_clockmultiplier and corecfg_baseclkfreq are still fine after
suspend / resume.
2. If I do pick this patch and I suspend/resume,
corecfg_clockmultiplier and corecfg_baseclkfreq are wrong after
suspend/resume (tested by reading /dev/mem directly from userspace
after suspend/resume).
Are you saying that it is unimportant that corecfg_clockmultiplier and
corecfg_baseclkfreq are wrong?
Yup, corecfg_* stuff will be reset after a power cycle.
I mean that we need only to guarantee they're correct at probe time.
Technically I think this should probably use "pm runtime" and not
normal suspend/resume hooks. Any time we end up pm runtime suspended
then I think our power will go off (because of genpd?) and we need to
restore values.
I understand your consideration. BUT genpd is in charge of on/off pd if the
corresponding device node has "power-domains" property. RPM is unnecessary
for this situation, we will not use autosuspend, right?
@shawn, what's your opinion?
I haven't dug. If Runtime PM isn't enabled for sdhci-of-arasan then I
guess we can just worry about suspend/resume, though.
-Doug
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