From: Grant Likely Subject: Re: [PATCH v7 1/1] spi/omap2_mcspi.c: Force CS to be in inactive state after off-mode transition Date: Wed, 29 Dec 2010 15:16:36 -0700 Message-ID: <20101229221636.GA15648@angua.secretlab.ca> References: <4D1B1305.4090709@free-electrons.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: spi-devel-general , linux-omap , Kevin Hilman , David Brownell To: Gregory CLEMENT Return-path: Content-Disposition: inline In-Reply-To: <4D1B1305.4090709@free-electrons.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-spi.vger.kernel.org On Wed, Dec 29, 2010 at 11:52:53AM +0100, Gregory CLEMENT wrote: > When SPI wake up from OFF mode, CS is in the wrong state: force it to the > inactive state. > > During the system life, I monitored the CS behavior using a oscilloscope. > I also activated debug in omap2_mcspi, so I saw when driver disable the clocks > and restore context when device is not used.Each time the CS was in the correct > state. It was only when system was put suspend to ram with off-mode activated > that on resume the CS was in wrong state( ie activated). > merged, thanks. g. > Changelog: > * Change from v1 to v2: > - Rebase on linus/master (after 2.6.37-rc1) > - Do some clean-up and fix indentation on both patches > - Add more explanations for patch 2 > > * Change from v2 to v3: > - Use directly resume function of spi_master instead of using function > - from spi_device as Grant Likely pointed it out. > - Force this transition explicitly for each CS used by a device. > > * Change from v3 to v4: > - Patch clean-up according to Kevin Hilman and checkpatch. > - Now force CS to be in inactive state only if it was inactive when it was > suspended. > > * Change from v4 to v5: > - Rebase on linus/master (after 2.6.37-rc3) > - Collapse some lines as pointed by Grant Likely > - Fix a spelling > > * Change from v5 to v6: > - Rebase on linus/master (after 2.6.37-rc7) > - Use CONFIG_SUSPEND instead of CONFIG_PM > - Didn't use legacy PM methods anymore. Instead, add a struct dev_pm_ops and > add the resume method there. > - Fix multi-line comment style > > * Change from v6 to v7: > - Rebase on linus/master (after 2.6.37-rc8) > - Drop an extra line > > Signed-off-by: Gregory CLEMENT > Acked-by: David Brownell > Reviewed-by: Kevin Hilman > > --- > drivers/spi/omap2_mcspi.c | 39 +++++++++++++++++++++++++++++++++++++++ > 1 files changed, 39 insertions(+), 0 deletions(-) > > diff --git a/drivers/spi/omap2_mcspi.c b/drivers/spi/omap2_mcspi.c > index 2a651e6..951a160 100644 > --- a/drivers/spi/omap2_mcspi.c > +++ b/drivers/spi/omap2_mcspi.c > @@ -1305,10 +1305,49 @@ static int __exit omap2_mcspi_remove(struct platform_device *pdev) > /* work with hotplug and coldplug */ > MODULE_ALIAS("platform:omap2_mcspi"); > > +#ifdef CONFIG_SUSPEND > +/* > + * When SPI wake up from off-mode, CS is in activate state. If it was in > + * unactive state when driver was suspend, then force it to unactive state at > + * wake up. > + */ > +static int omap2_mcspi_resume(struct device *dev) > +{ > + struct spi_master *master = dev_get_drvdata(dev); > + struct omap2_mcspi *mcspi = spi_master_get_devdata(master); > + struct omap2_mcspi_cs *cs; > + > + omap2_mcspi_enable_clocks(mcspi); > + list_for_each_entry(cs, &omap2_mcspi_ctx[master->bus_num - 1].cs, > + node) { > + if ((cs->chconf0 & OMAP2_MCSPI_CHCONF_FORCE) == 0) { > + > + /* > + * We need to toggle CS state for OMAP take this > + * change in account. > + */ > + MOD_REG_BIT(cs->chconf0, OMAP2_MCSPI_CHCONF_FORCE, 1); > + __raw_writel(cs->chconf0, cs->base + OMAP2_MCSPI_CHCONF0); > + MOD_REG_BIT(cs->chconf0, OMAP2_MCSPI_CHCONF_FORCE, 0); > + __raw_writel(cs->chconf0, cs->base + OMAP2_MCSPI_CHCONF0); > + } > + } > + omap2_mcspi_disable_clocks(mcspi); > + return 0; > +} > +#else > +#define omap2_mcspi_resume NULL > +#endif > + > +static const struct dev_pm_ops omap2_mcspi_pm_ops = { > + .resume = omap2_mcspi_resume, > +}; > + > static struct platform_driver omap2_mcspi_driver = { > .driver = { > .name = "omap2_mcspi", > .owner = THIS_MODULE, > + .pm = &omap2_mcspi_pm_ops > }, > .remove = __exit_p(omap2_mcspi_remove), > }; > -- > 1.7.0.4 >