linux-kernel - 答复: [PATCH] mfd: Fix RTS5227 (and others) powermanagement

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Date:   Thu, 7 Dec 2017 02:38:47 +0000
From:   冯锐 <rui_feng@...lsil.com.cn>
To:     Hans de Goede <hdegoede@...hat.com>,
        Lee Jones <lee.jones@...aro.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: 答复: [PATCH] mfd: Fix RTS5227 (and others) powermanagement

> Hi,
> 
> On 06-12-17 12:21, Hans de Goede wrote:
> > Commit 8275b77a1513 ("mfd: rts5249: Add support for RTS5250S power
> > saving") adds powersaving support for device-ids 5249 524a and 525a.
> >
> > But as a side effect it breaks ASPM support for all the other
> > device-ids, causing e.g. the Haswell CPU on a Lenovo T440s to not go
> > into a higher c-state then PC3, while previously it would go to PC7,
> > causing the machine to idle at 7.4W instead of 6.6W!
> >
> > The problem here is the new option.dev_aspm_mode field, which only
> > gets explicitly initialized in the new code for the device-ids 5249
> > 524a and 525a. Leaving the dev_aspm_mode 0 for the other device-ids.
> >
> > The default dev_aspm_mode 0 is mapped to DEV_ASPM_DISABLE, but the
> old
> > behavior of calling rtsx_pci_enable_aspm() when idle and
> > rtsx_pci_disable_aspm() when busy happens when dev_aspm_mode ==
> > DEV_ASPM_DYNAMIC.
> >
> > This commit changes the enum so that 0 = DEV_ASPM_DYNAMIC matching
> the
> > old default behavior, fixing the pm regression with the other device-ids.
> >
> > Cc: Rui Feng <rui_feng@...lsil.com.cn>
> > Signed-off-by: Hans de Goede <hdegoede@...hat.com>
> 
> p.s.
> 
> 2 remarks:
> 
> 1. As this is a regression in 4.15, please queue this up as a fix for 4.15
>     (I prioritized bisecting this, which took me a whole day to get a fix
>      ready in time for 4.15).
> 
> 2. This bit of the original commit also looks weird, but I don't have the
> hardware in case, Rui Feng should probably take a look at this:
> 
> @@ -1063,6 +1185,16 @@ static int rtsx_pci_init_hw(struct rtsx_pcr *pcr)
>   	if (err < 0)
>   		return err;
> 
> +	switch (PCI_PID(pcr)) {
> +	case PID_5250:
> +	case PID_524A:
> +	case PID_525A:
> +		rtsx_pci_write_register(pcr, PM_CLK_FORCE_CTL, 1, 1);
> +		break;
> +	default:
> +		break;
> +	}
> +
>   	/* Enable clk_request_n to enable clock power management */
>   	rtsx_pci_write_config_byte(pcr, pcr->pcie_cap + PCI_EXP_LNKCTL + 1, 1);
>   	/* Enter L1 when host tx idle */
> 
> The PID5250 looks weird here, the rtsx_pci_ids table does not contain it; and
> neither does the switch (PCI_PID(pcr)) in rtsx_pci_init_chip() at the same time
> the commit does make changes to the codepaths for the 5249... ?
> 
Thank you for pointing out the problem. The old driver isn't written by me, 5249, 524a and 525a are in the same file,
I didn't notice that rtsx_pci_ids table does not contain 5250. But the power saving function for 5250 and 525a is the same,
PID_5250 here will not effect the power saving function.

> Regards,
> 
> Hans
> 
> 
> 
> 
> 
> 
> 
> > ---
> >   include/linux/mfd/rtsx_pci.h | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/include/linux/mfd/rtsx_pci.h
> > b/include/linux/mfd/rtsx_pci.h index a2a1318a3d0c..c3d3f04d8cc6 100644
> > --- a/include/linux/mfd/rtsx_pci.h
> > +++ b/include/linux/mfd/rtsx_pci.h
> > @@ -915,10 +915,10 @@ enum PDEV_STAT  {PDEV_STAT_IDLE,
> PDEV_STAT_RUN};
> >   #define LTR_L1SS_PWR_GATE_CHECK_CARD_EN	BIT(6)
> >
> >   enum dev_aspm_mode {
> > -	DEV_ASPM_DISABLE = 0,
> >   	DEV_ASPM_DYNAMIC,
> >   	DEV_ASPM_BACKDOOR,
> >   	DEV_ASPM_STATIC,
> > +	DEV_ASPM_DISABLE,
> >   };
> >
> >   /*
> >
> 
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