diff options
| author | Anson Huang <b20788@freescale.com> | 2013-12-24 17:19:21 -0500 |
|---|---|---|
| committer | Shawn Guo <shawn.guo@linaro.org> | 2013-12-31 09:36:48 +0800 |
| commit | 48c95841110036a95840c6782f27d841ead9a583 (patch) | |
| tree | 2549fedb49658f07058a075a0c4c6a2a937090b6 /arch/arm/mach-imx | |
| parent | b4e844f019aa6b46601ef3d04af645b36dffaa0d (diff) | |
ARM: imx: improve the comment of CCM lpm SW workaround
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 <b20788@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Diffstat (limited to 'arch/arm/mach-imx')
| -rw-r--r-- | arch/arm/mach-imx/pm-imx6q.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/arch/arm/mach-imx/pm-imx6q.c b/arch/arm/mach-imx/pm-imx6q.c index aecd9f8037e0..9d47adc078aa 100644 --- a/arch/arm/mach-imx/pm-imx6q.c +++ b/arch/arm/mach-imx/pm-imx6q.c @@ -156,10 +156,16 @@ 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). */ iomuxc_irq_desc = irq_to_desc(32); imx_gpc_irq_unmask(&iomuxc_irq_desc->irq_data); @@ -219,6 +225,8 @@ 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. |