On Tue, Dec 24, 2013 at 05:19:21PM -0500, Anson Huang wrote: > Improve the comment of SW workaround for CCM lpm issue using > hardware errata description to avoid confusion. > > ERR007265: > CCM: When improper low-power sequence is used, the SoC enters > low power mode before the ARM core executes WFI. > > Software workaround: > 1) Software should trigger IRQ #32 (IOMUX) to be always pending > by setting IOMUX_GPR1_GINT. > 2) Software should then unmask IRQ #32 in GPC before setting CCM > Low-Power mode. > 3) Software should mask IRQ #32 right after CCM Low-Power mode is > set (set bits 0-1 of CCM_CLPCR). > > Signed-off-by: Anson Huang <[email protected]> > --- > arch/arm/mach-imx/pm-imx6q.c | 13 +++++++++---- > 1 file changed, 9 insertions(+), 4 deletions(-) > > diff --git a/arch/arm/mach-imx/pm-imx6q.c b/arch/arm/mach-imx/pm-imx6q.c > index aecd9f8..31cb9d6 100644 > --- a/arch/arm/mach-imx/pm-imx6q.c > +++ b/arch/arm/mach-imx/pm-imx6q.c > @@ -156,10 +156,13 @@ int imx6q_set_lpm(enum mxc_cpu_pwr_mode mode) > } > > /* > - * Unmask the always pending IOMUXC interrupt #32 as wakeup source to > - * deassert dsm_request signal, so that we can ensure dsm_request > - * is not asserted when we're going to write CLPCR register to set LPM. > - * After setting up LPM bits, we need to mask this wakeup source. > + * ERR007265: > + * CCM: When improper low-power sequence is used, the SoC enters low > power mode before the ARM core executes WFI. > + * > + * Software workaround: > + * 1) Software should trigger IRQ #32 (IOMUX) to be always pending by > setting IOMUX_GPR1_GINT. > + * 2) Software should then unmask IRQ #32 in GPC before setting CCM > Low-Power mode. > + * 3) Software should mask IRQ #32 right after CCM Low-Power mode is > set (set bits 0-1 of CCM_CLPCR).
The lines are too long. I wrapped them a little bit, and applied the patch. Shawn > */ > iomuxc_irq_desc = irq_to_desc(32); > imx_gpc_irq_unmask(&iomuxc_irq_desc->irq_data); > @@ -219,6 +222,8 @@ void __init imx6q_pm_init(void) > WARN_ON(!ccm_base); > > /* > + * This is for SW workaround step #1 of ERR007265, see comments > + * in imx6q_set_lpm for details of this errata. > * Force IOMUXC irq pending, so that the interrupt to GPC can be > * used to deassert dsm_request signal when the signal gets > * asserted unexpectedly. > -- > 1.7.9.5 > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
