Return-Path: <0100016307676ed2-fd5830a5-1933-4fc2-b356-a5112a65579f-000000@amazonses.com>
Subject: Re: [PATCH] Bluetooth: btusb: Only check needs_reset_resume DMI table
 for QCA rome chipsets
To: Hans de Goede <hdegoede@redhat.com>, Marcel Holtmann
 <marcel@holtmann.org>, Gustavo Padovan <gustavo@padovan.org>,
 Johan Hedberg <johan.hedberg@gmail.com>
Cc: linux-bluetooth@vger.kernel.org, stable@vger.kernel.org,
 Jeremy Cline <jcline@redhat.com>
References: <20180427092643.27140-1-hdegoede@redhat.com>
From: Jeremy Cline <jeremy@jcline.org>
Message-ID: <0100016307676ed2-fd5830a5-1933-4fc2-b356-a5112a65579f-000000@email.amazonses.com>
Date: Fri, 27 Apr 2018 14:00:09 +0000
MIME-Version: 1.0
In-Reply-To: <20180427092643.27140-1-hdegoede@redhat.com>
Content-Type: text/plain; charset=utf-8
List-ID: <linux-bluetooth.vger.kernel.org>

On 04/27/2018 05:26 AM, Hans de Goede wrote:
> Jeremy Cline correctly points out in rhbz#1514836 that a device where the
> QCA rome chipset needs the USB_QUIRK_RESET_RESUME quirk, may also ship
> with a different wifi/bt chipset in some configurations.
> 
> If that is the case then we are needlessly penalizing those other chipsets
> with a reset-resume quirk, typically causing 0.4W extra power use because
> this disables runtime-pm.
> 
> This commit moves the DMI table check to a btusb_check_needs_reset_resume()
> helper (so that we can easily also call it for other chipsets) and calls
> this new helper only for QCA_ROME chipsets for now.
> 
> BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1514836
> Cc: stable@vger.kernel.org
> Cc: Jeremy Cline <jcline@redhat.com>
> Suggested-by: Jeremy Cline <jcline@redhat.com>
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>  drivers/bluetooth/btusb.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index f064984c9ec0..15e7cdca6eb5 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -2863,6 +2863,12 @@ static int btusb_config_oob_wake(struct hci_dev *hdev)
>  }
>  #endif
>  
> +static void btusb_check_needs_reset_resume(struct usb_interface *intf)
> +{
> +	if (dmi_check_system(btusb_needs_reset_resume_table))
> +		interface_to_usbdev(intf)->quirks |= USB_QUIRK_RESET_RESUME;
> +}
> +
>  static int btusb_probe(struct usb_interface *intf,
>  		       const struct usb_device_id *id)
>  {
> @@ -2985,9 +2991,6 @@ static int btusb_probe(struct usb_interface *intf,
>  	hdev->send   = btusb_send_frame;
>  	hdev->notify = btusb_notify;
>  
> -	if (dmi_check_system(btusb_needs_reset_resume_table))
> -		interface_to_usbdev(intf)->quirks |= USB_QUIRK_RESET_RESUME;
> -
>  #ifdef CONFIG_PM
>  	err = btusb_config_oob_wake(hdev);
>  	if (err)
> @@ -3076,6 +3079,7 @@ static int btusb_probe(struct usb_interface *intf,
>  		data->setup_on_usb = btusb_setup_qca;
>  		hdev->set_bdaddr = btusb_set_bdaddr_ath3012;
>  		set_bit(HCI_QUIRK_SIMULTANEOUS_DISCOVERY, &hdev->quirks);
> +		btusb_check_needs_reset_resume(intf);

If we later need the quirk applied to an Intel chipset for a particular
DMI, this call would get added to the Intel block and then the quirk
would start getting applied to the Intel variety of the XPS 13 9360
again, right?

I have a feeling that's a rather large "if" and I don't have any idea
how likely it is. Is it even something worth worrying about?

Regards,
Jeremy