linux-kernel - Re: [PATCH 0/6] mmc/memstick: rtsx

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Message-ID: <CAPDyKFpzq2wRfh_5x119ouP-e8EAaibsSvM36msxm7oepxRoDQ@mail.gmail.com>
Date:   Mon, 17 Oct 2016 15:49:55 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     linux-mmc <linux-mmc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Ritesh Raj Sarraf <rrs@...earchut.com>,
        Alan Stern <stern@...land.harvard.edu>,
        Oliver Neukum <oneukum@...e.com>,
        USB list <linux-usb@...r.kernel.org>,
        Roger Tseng <rogerable@...ltek.com>,
        Wei WANG <wei_wang@...lsil.com.cn>
Subject: Re: [PATCH 0/6] mmc/memstick: rtsx_usb: Fix runtime PM issues

On 13 October 2016 at 13:37, Ulf Hansson <ulf.hansson@...aro.org> wrote:
> The rtsx_usb_sdmmc (mmc/sd) and rtsx_usb_ms (memstick) devices are interfacing
> an rtsx_usb device (managed by an mfd driver) while communicating with the
> cards. The mmc/sd and memstick devices are children of the usb device.
>
> Issues has been reported [1] for rtsx, which have been investigated, discussed,
> fixed, tested, etc, particularly when using mmc/sd cards. During the
> investigation, some changes was proposed and tested successfully. In this
> series I have picked up these changes and created some proper patches with
> change-logs.
>
> It turned out that most of the problems was related to the runtime PM
> deployment in the memstick and the mmc/sd driver, which are fixed in this
> series.
>
> A couple of more issues were also discussed [2], which needs to be fixed as
> well. Although they are out of scope for this series, so we will have to look
> into those at a later point. Here's a brief summary of these leftovers:
>
> *)
> It seems reasonable to turn off autosuspend for usb devices and instead rely on
> the usb device's children to deal with autosuspend. The reason is simply that
> the children has better knowledge of when using autosuspend makes sense.
>
> **)
> Polling card detect mode is used both for mmc/sd and memstick. Because of the
> lack of synchronization between the polling attempts for these subsystems, the
> usb device may be powered on for unnecessary long intervals, thus we are
> wasting power.
>
> Besides the above changes, I folded in a change in the mmc core which improves
> the behaviour for mmc hosts using MMC_CAP2_NO_PRESCAN_POWERUP, which is the
> case for the rtsx_usb_sdmmc driver.  This change should improve the boot time
> with ~100ms per rtsx_usb_sdmmc device.
>
> Finally, as I couldn't find an active maintainer for the memstick
> subsystem/driver and because the author of the drivers can be reached, I
> volunteer to take this all through my mmc tree. Please tell me if that is
> problem to any of you.
>
> [1]
> https://www.spinics.net/lists/linux-usb/msg146998.html
> [2]
> https://www.spinics.net/lists/linux-mmc/msg39235.html
>
>
> Alan Stern (1):
>   memstick: rtsx_usb_ms: Runtime resume the device when polling for
>     cards
>
> Ulf Hansson (5):
>   mmc: rtsx_usb_sdmmc: Avoid keeping the device runtime resumed when
>     unused
>   mmc: rtsx_usb_sdmmc: Handle runtime PM while changing the led
>   memstick: rtsx_usb_ms: Manage runtime PM when accessing the device
>   mmc: rtsx_usb_sdmmc: Enable runtime PM autosuspend
>   mmc: core: Don't power off the card when starting the host
>
>  drivers/memstick/host/rtsx_usb_ms.c |  6 ++++++
>  drivers/mmc/core/core.c             |  9 ++++-----
>  drivers/mmc/host/rtsx_usb_sdmmc.c   | 10 +++++-----
>  3 files changed, 15 insertions(+), 10 deletions(-)
>
> --
> 1.9.1
>

Patch 1->4 applied for fixes. Holding patch 5->6 for a while, as they
are intended for next!

Kind regards
Uffe