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

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Date:   Wed, 6 Dec 2017 12:31:31 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     linux-kernel@...r.kernel.org, Rui Feng <rui_feng@...lsil.com.cn>
Subject: Re: [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... ?

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,
>   };
>   
>   /*
>