Re: [PATCH v7 1/1] spi/omap2_mcspi.c: Force CS to be in inactive state after off-mode transition

[Grant Likely <grant.likely@secretlab.ca>]

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 <gregory.clement@free-electrons.com>
> Acked-by: David Brownell <dbrownell@users.sourceforge.net>
> Reviewed-by: Kevin Hilman <khilman@deeprootsystems.com>
> 
> ---
>  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
>