linux-kernel - [PATCH-v2 0/4] mmc: switch to 1-bit mode which stopping clocks.

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Date:	Sat, 31 Jan 2015 06:05:37 +1100
From:	NeilBrown <neilb@...e.de>
To:	Tony Lindgren <tony@...mide.com>,
	Ulf Hansson <ulf.hansson@...aro.org>
Cc:	GTA04 owners <gta04-owner@...delico.com>,
	linux-omap@...r.kernel.org, linux-mmc@...r.kernel.org,
	linux-kernel@...r.kernel.org, Andreas Fenkart <afenkart@...il.com>
Subject: [PATCH-v2 0/4] mmc: switch to 1-bit mode which stopping clocks.

This is a new version which moves most of the code into
mmc/core so it is available to all drivers.

I was wrong about not being able to sleep in pm_runtime callbacks.
There are spinlocks, but not the ones I thought they were...

Anyway, I tried switching to 1-bit mode from within the
runtime_suspend callback and hit a different problem.
The sequence to switch to 1-bit involves calling set_ios
which, for omap_hsmmc at least, calls pm_runtime_get_sync().

Calling pm_runtime_get_sync from the runtime_suspend callback
deadlocks.

It would be possible to remove the pm_runtime_get_sync call
from set_ios() functions, and instead call host->enable(),
host->disable() around those mmc_set_ios() calls which don't
have the host claimed.  However that seems a bit fragile to me.

So for now I'm persisting with doing the width change from
a work-queue.  This set of patches does that.

If you think calling host->enable/disable around mmc_set_ios() calls
does make sense, I can post my other patch for review.

Thanks,
NeilBrown

---

NeilBrown (4):
      mmc: core: fold mmc_set_bus_width calls into sdio_enable_4bit_bus.
      mmc: core: allow non-blocking form of mmc_claim_host
      mmc: sdio: support switching to 1-bit before turning off clocks
      mmc: omap_hsmmc: switch to 1-bit before stopping clocks.

 drivers/mmc/core/core.c       |   21 +++++++++---
 drivers/mmc/core/sdio.c       |   74 +++++++++++++++++++++++++++++------------
 drivers/mmc/host/omap_hsmmc.c |   13 ++++++-
 include/linux/mmc/core.h      |    2 +
 include/linux/mmc/host.h      |    2 +
 5 files changed, 83 insertions(+), 29 deletions(-)

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