On Mon, Dec 20, 2010 at 11:23:27AM +0100, ext Jean Pihet wrote: > On Sat, Dec 18, 2010 at 11:53 PM, Nishanth Menon <nm@xxxxxx> wrote: > > From: Peter 'p2' De Schrijver <peter.de-schrijver@xxxxxxxxx> > > > > Erratum i581 impacts OMAP3 platforms. > > PRCM DPLL control FSM removes SDRC_IDLEREQ before DPLL3 locks causing > > the DPLL not to be locked at times. > > > > IMPORTANT: > > *) This is not a complete workaround implementation as recommended > > by the silicon erratum. this is a support logic for detecting lockups and > > attempting to recover where possible and is known to provide stability > > in multiple platforms. > > *) This code is mostly important for inactive and retention. The ROM code > > waits for the maximum dll lock time when resuming from off mode. So for > > off mode this code isn't really needed. > > > > This should eventually get refactored as part of cleanups to sleep34xx.S > > > > Cc: Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx> > > Cc: Tony Lindgren <tony@xxxxxxxxxxx> > > > > Signed-off-by: Peter 'p2' De Schrijver <peter.de-schrijver@xxxxxxxxx> > > --- > > (no change done, posting for completeness of the series) > > v2: https://patchwork.kernel.org/patch/365252/ > > typo correction- erratum, support, added comment from Peter from the > > thread to commit message > > v1: http://marc.info/?l=linux-omap&m=129013172525234&w=2 > > arch/arm/mach-omap2/sleep34xx.S | 52 +++++++++++++++++++++++++++++++++++--- > > 1 files changed, 47 insertions(+), 5 deletions(-) > > > > diff --git a/arch/arm/mach-omap2/sleep34xx.S b/arch/arm/mach-omap2/sleep34xx.S > > index 2c20fcf..3fbd1e5 100644 > > --- a/arch/arm/mach-omap2/sleep34xx.S > > +++ b/arch/arm/mach-omap2/sleep34xx.S > > @@ -42,6 +42,7 @@ > > OMAP3430_PM_PREPWSTST) > > #define PM_PWSTCTRL_MPU_P OMAP3430_PRM_BASE + MPU_MOD + OMAP2_PM_PWSTCTRL > > #define CM_IDLEST1_CORE_V OMAP34XX_CM_REGADDR(CORE_MOD, CM_IDLEST1) > > +#define CM_IDLEST_CKGEN_V OMAP34XX_CM_REGADDR(PLL_MOD, CM_IDLEST) > > #define SRAM_BASE_P 0x40200000 > > #define CONTROL_STAT 0x480022F0 > > #define SCRATCHPAD_MEM_OFFS 0x310 /* Move this as correct place is > > @@ -554,31 +555,67 @@ skip_l2_inval: > > > > /* Make sure SDRC accesses are ok */ > > wait_sdrc_ok: > > + > > +/* DPLL3 must be locked before accessing the SDRC. Maybe the HW ensures this. */ > > + ldr r4, cm_idlest_ckgen > > +wait_dpll3_lock: > > + ldr r5, [r4] > > + tst r5, #1 > > + beq wait_dpll3_lock > > + > > ldr r4, cm_idlest1_core > > +wait_sdrc_ready: > > ldr r5, [r4] > > - and r5, r5, #0x2 > > - cmp r5, #0 > > - bne wait_sdrc_ok > > + tst r5, #0x2 > > + bne wait_sdrc_ready > > + /* allow DLL powerdown upon hw idle req */ > > ldr r4, sdrc_power > > ldr r5, [r4] > > bic r5, r5, #0x40 > > str r5, [r4] > > -wait_dll_lock: > > +is_dll_in_lock_mode: > > + > > /* Is dll in lock mode? */ > > ldr r4, sdrc_dlla_ctrl > > ldr r5, [r4] > > tst r5, #0x4 > > bxne lr > > /* wait till dll locks */ > > - ldr r4, sdrc_dlla_status > > +wait_dll_lock_timed: > > + ldr r4, wait_dll_lock_counter > > + add r4, r4, #1 > > + str r4, wait_dll_lock_counter > > + ldr r4, sdrc_dlla_status > > + mov r6, #8 /* Wait 20uS for lock */ > > +wait_dll_lock: > > + subs r6, r6, #0x1 > > + beq kick_dll > > It would be good to have more comments on the code flow here: > - what are wait_dll_lock_counter and kick_counter used for? For debugging and statistics. So you can find out how many times a 'kick' was needed. > - what is the timing based on? Why 20uS for the wait time? This is the maximum lock time of the dll according to TI for OMAP3430. > - jumping back and forth to kick_dll and wait_dll_lock_timed is confusing. > > > ldr r5, [r4] > > and r5, r5, #0x4 > > cmp r5, #0x4 > > bne wait_dll_lock > > bx lr > > > > + /* disable/reenable DLL if not locked */ > > +kick_dll: > > + ldr r4, sdrc_dlla_ctrl > > + ldr r5, [r4] > > + mov r6, r5 > > + bic r6, #(1<<3) /* disable dll */ > > + str r6, [r4] > > + dsb > > + orr r6, r6, #(1<<3) /* enable dll */ > > + str r6, [r4] > > + dsb > > + ldr r4, kick_counter > > + add r4, r4, #1 > > + str r4, kick_counter > > + b wait_dll_lock_timed > > + > > cm_idlest1_core: > > .word CM_IDLEST1_CORE_V > > +cm_idlest_ckgen: > > + .word CM_IDLEST_CKGEN_V > > sdrc_dlla_status: > > .word SDRC_DLLA_STATUS_V > > sdrc_dlla_ctrl: > > @@ -615,5 +652,10 @@ control_stat: > > .word CONTROL_STAT > > kernel_flush: > > .word v7_flush_dcache_all > > + /* these 2 words need to be at the end !!! */ > > +kick_counter: > > + .word 0 > > +wait_dll_lock_counter: > > + .word 0 > Why do they need to be at the end? Also, at the end of what do they need to be? > At the end of omap34xx_cpu_suspend. As we don't know where in SRAM the counters will be, the code accessing those counters addresses them relative from (_omap_sram_idle + omap34xx_cpu_suspend_sz). Not sure if this part of the code made it to linux-omap though. Cheers, Peter. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
