On Mon, 14 Sep 2015 13:43:32 +0530
Vaibhav Hiremath [off-list ref] wrote:

On Monday 14 September 2015 11:58 AM, Jisheng Zhang wrote:

quoted

On Mon, 14 Sep 2015 11:55:56 +0530
Vaibhav Hiremath [off-list ref] wrote:

quoted

On Thursday 10 September 2015 01:34 PM, Jisheng Zhang wrote:

quoted

Hi Russell,

On Thu, 10 Sep 2015 09:02:33 +0100
Russell King - ARM Linux [off-list ref] wrote:

quoted

On Thu, Sep 10, 2015 at 03:31:29PM +0800, Jisheng Zhang wrote:

quoted

Hi Vaibhav,

On Thu, 10 Sep 2015 12:40:48 +0530
Vaibhav Hiremath [off-list ref] wrote:

quoted

Hi,

During my testing of SDHCI-PXAV3 driver on Marvell's pxa1928
based platform, I observed that runtime PM suspend/resume is having
issues with card insertion and removal.

Let me try to explain it using execution sequence -

During boot:

MMC SD card gets detected as expected.

[    2.431012] mmc1: new high speed SDHC card at address 1234
[    2.437235] mmcblk1: mmc1:1234 SA04G 3.63 GiB
[    2.444841]  mmcblk1: p1


Now after coming to the linux prompt, if card removal event occurs
then the call sequence is -

    sdhci_irq() -->
     -> sdhci_thread_irq(): host->thread_isr - 0x80
        -> sdhci_card_event()
        -> mmc_detect_change()
           --> _mmc_detect_change()
               --->  mmc_sd_detect()
                     mmc_sd_remove()
                     mmc_remove_card()
                     mmc_bus_remove()
                     mmc_power_off()
                     mmc_set_initial_state()
                     sdhci_set_ios()
                     ...
          sdhci_pxav3_runtime_suspend()
          sdhci_runtime_suspend_host()


Till here everything looks perfect :) (if I got it right)

Now on card insertion again, the expectation is, runtime resume should
get called as part of interrupt trigger from the SDHCI controller on
card insertion.

AFAIK, card insertion => wakeup irq, this irq doesn't come from SDHCI

Wakeup IRQs are what happens when the _system_ is in suspend, not
when the device is runtime suspended.

Oh, yes. Sorry for misleading, I didn't express myself clearly. What
I really means is that the card insertion/remove irq which could finally
cause sdhci host resumed.

So Jisheng,

You are ok with above change, right?

Nope. the above is just to clarify my mixing "wakeup IRQs" and the card
insertion/remove irq that brings sdhci host resumed.

IMHO, your patch is still not necessary and perhaps wrong.

Don't be in hurry to conclude,
Let's understand the technical aspect fist.


Let me clarify once again here,


The card detect interrupt is coming from SDHCI controller itself,

But how the SDHCI controller generate CD interrupt when it's in runtime suspended
state, i.e clock gated or power gated?

I have confirmed that the runtime PM is working perfectly fine,
clock is gated/disabled on card removal.

But seems we still didn't know the sdhci host is clock gated or power gated.

Clock Gating:
=============
#
# devmem 0xd4282854
0x0000181B
# [ 1318.948460] mmc1: card 1234 removed

#
# devmem 0xd4282854
0x00001800
#

Can you plz read the SDHCI host registers after this step? If the host is
clock gated, we should get "asynchronous external abort" in theory.

Thanks