linux-kernel - Re: [PATCH V1] mmc: sdhci-msm: Set IO pins in low power state during suspend

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Date:   Fri, 10 Jul 2020 17:19:48 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Veerabhadrarao Badiganti <vbadigan@...eaurora.org>
Cc:     adrian.hunter@...el.com, ulf.hansson@...aro.org,
        bjorn.andersson@...aro.org, linux-mmc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        Andy Gross <agross@...nel.org>
Subject: Re: [PATCH V1] mmc: sdhci-msm: Set IO pins in low power state during
 suspend

Hi,

On Fri, Jul 10, 2020 at 04:28:36PM +0530, Veerabhadrarao Badiganti wrote:
> Hi Mathias,
> 
> On 7/10/2020 6:22 AM, Matthias Kaehlcke wrote:
> > Hi,
> > 
> > On Wed, Jul 08, 2020 at 06:41:20PM +0530, Veerabhadrarao Badiganti wrote:
> > > Configure SDHC IO pins with low power configuration when the driver
> > > is in suspend state.
> > > 
> > > Signed-off-by: Veerabhadrarao Badiganti <vbadigan@...eaurora.org>
> > > ---
> > >   drivers/mmc/host/sdhci-msm.c | 17 +++++++++++++++++
> > >   1 file changed, 17 insertions(+)
> > > 
> > > diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
> > > index 392d41d57a6e..efd2bae1430c 100644
> > > --- a/drivers/mmc/host/sdhci-msm.c
> > > +++ b/drivers/mmc/host/sdhci-msm.c
> > > @@ -15,6 +15,7 @@
> > >   #include <linux/iopoll.h>
> > >   #include <linux/regulator/consumer.h>
> > >   #include <linux/interconnect.h>
> > > +#include <linux/pinctrl/consumer.h>
> > >   #include "sdhci-pltfm.h"
> > >   #include "cqhci.h"
> > > @@ -1352,6 +1353,19 @@ static void sdhci_msm_set_uhs_signaling(struct sdhci_host *host,
> > >   		sdhci_msm_hs400(host, &mmc->ios);
> > >   }
> > > +static int sdhci_msm_set_pincfg(struct sdhci_msm_host *msm_host, bool level)
> > > +{
> > > +	struct platform_device *pdev = msm_host->pdev;
> > > +	int ret;
> > > +
> > > +	if (level)
> > > +		ret = pinctrl_pm_select_default_state(&pdev->dev);
> > > +	else
> > > +		ret = pinctrl_pm_select_sleep_state(&pdev->dev);
> > > +
> > > +	return ret;
> > > +}
> > > +
> > >   static int sdhci_msm_set_vmmc(struct mmc_host *mmc)
> > >   {
> > >   	if (IS_ERR(mmc->supply.vmmc))
> > > @@ -1596,6 +1610,9 @@ static void sdhci_msm_handle_pwr_irq(struct sdhci_host *host, int irq)
> > >   			ret = sdhci_msm_set_vqmmc(msm_host, mmc,
> > >   					pwr_state & REQ_BUS_ON);
> > >   		if (!ret)
> > > +			ret = sdhci_msm_set_pincfg(msm_host,
> > > +					pwr_state & REQ_BUS_ON);
> > > +		if (!ret)
> > >   			irq_ack |= CORE_PWRCTL_BUS_SUCCESS;
> > >   		else
> > >   			irq_ack |= CORE_PWRCTL_BUS_FAIL;
> > I happened to have a debug patch in my tree which logs when regulators
> > are enabled/disabled, with this patch I see the SD card regulator
> > toggling constantly after returning from the first system suspend.
> > 
> > I added more logs:
> > 
> > [ 1156.085819] DBG: sdhci_msm_set_pincfg: level = 0 (ret: 0)
> > [ 1156.248936] DBG: sdhci_msm_set_pincfg: level = 1 (ret: 0)
> > [ 1156.301989] DBG: sdhci_msm_set_pincfg: level = 0 (ret: 0)
> > [ 1156.462383] DBG: sdhci_msm_set_pincfg: level = 1 (ret: 0)
> > [ 1156.525988] DBG: sdhci_msm_set_pincfg: level = 0 (ret: 0)
> > [ 1156.670372] DBG: sdhci_msm_set_pincfg: level = 1 (ret: 0)
> > [ 1156.717935] DBG: sdhci_msm_set_pincfg: level = 0 (ret: 0)
> > [ 1156.878122] DBG: sdhci_msm_set_pincfg: level = 1 (ret: 0)
> > [ 1156.928134] DBG: sdhci_msm_set_pincfg: level = 0 (ret: 0)
> > 
> > This is on an SC7180 platform. It doesn't run an upstream kernel though,
> > but v5.4 with plenty of upstream patches.
> I have verified this on couple of sc7180 targets (on Chrome platform with
> Chrome kernel).
> But didn't see any issue. Its working as expected.

Did you test system suspend too? At least in the Chrome OS kernel tree system
suspend is not supported yet in the main branch, you'd need a pile of 30+
extra patches to get it to work. This is expected to change soon though :)

> Let me know if you are observing this issue constantly on multiple boards, I
> will share you
> a debug patch to check it further.

I currently have only one board with the SD card slot populated, I might
get another one next week.

The toggling occurs only when no SD card is inserted.