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

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Date:   Thu, 7 Dec 2017 09:28:18 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     冯锐 <rui_feng@...lsil.com.cn>
Cc:     Hans de Goede <hdegoede@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: 答复: [PATCH] mfd: Fix RTS5227
 (and others) powermanagement

On Thu, 07 Dec 2017, 冯锐 wrote:

> > 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.

Is that an Ack or a NAck?

-- 
Lee Jones
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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