Jean, > -----Original Message----- > From: linux-omap-owner@xxxxxxxxxxxxxxx [mailto:linux-omap- > owner@xxxxxxxxxxxxxxx] On Behalf Of jean.pihet@xxxxxxxxxxxxxx > Sent: Thursday, January 13, 2011 9:49 PM > To: linux-omap@xxxxxxxxxxxxxxx > Cc: Jean Pihet > Subject: [RFC/PATCH] OMAP3: run the ASM sleep code from DDR > > From: Jean Pihet <j-pihet@xxxxxx> > > Most of the ASM sleep code (in arch/arm/mach-omap2/sleep34xx.S) > is copied to internal SRAM and run from there. > However only a small part of the code really needs to run from > internal SRAM. > > This fix lets most of the ASM idle code run from the DDR > in order to minimize the SRAM usage. No performance > loss or gain can be measured with a 32KHz clock period. > > The only pieces of code that are mandatory in SRAM > are: > - the i443 erratum WA, > - the i581 erratum WA, > - the security extension code. > > SRAM usage: > - original code: > . 560 bytes for omap3_sram_configure_core_dpll (used by DVFS), > . 1368 bytes for omap_sram_idle (used by suspend/resume in > RETention), > . 124 bytes for es3_sdrc_fix (used by suspend/resume in OFF mode > on ES3.x), > . 108 bytes for save_secure_ram_context (used on HS parts). > > With this fix the usage for suspend/resume in RETention goes down > 312 bytes, so the > gain in SRAM usage for suspend/resume is > 1KB. > > Tested on OMAP3EVM, Beagleboard (ES2.x) and N900 (ES3.1) > in idle with full RET and OFF modes. > > Signed-off-by: Jean Pihet <j-pihet@xxxxxx> > --- > arch/arm/mach-omap2/pm.h | 19 ++- > arch/arm/mach-omap2/pm34xx.c | 19 ++- > arch/arm/mach-omap2/sleep34xx.S | 299 +++++++++++++++++++++++----- > ----------- > 3 files changed, 200 insertions(+), 137 deletions(-) > [...] > diff --git a/arch/arm/mach-omap2/sleep34xx.S b/arch/arm/mach- > omap2/sleep34xx.S > index 98d8232..ced85b5 100644 > --- a/arch/arm/mach-omap2/sleep34xx.S > +++ b/arch/arm/mach-omap2/sleep34xx.S > @@ -163,8 +163,10 @@ ENTRY(save_secure_ram_context_sz) > * > * > * Notes: > - * - this code gets copied to internal SRAM at boot and after wake- > up > - * from OFF mode. The execution pointer in SRAM is > _omap_sram_idle. > + * - only the minimum set of functions gets copied to internal SRAM > at boot > + * and after wake-up from OFF mode, cf. omap_push_sram_idle. The > function > + * pointers in SDRAM or SRAM are called depending on the desired > low power > + * target state. > * - when the OMAP wakes up it continues at different execution > points > * depending on the low power mode (non-OFF vs OFF modes), > * cf. 'Resume path for xxx mode' comments. > @@ -181,9 +183,15 @@ ENTRY(omap34xx_cpu_suspend) > * 3 - Both L1 and L2 lost > */ > > - /* Directly jump to WFI is the context save is not required */ > - cmp r1, #0x0 > - beq omap3_do_wfi > + /* > + * For OFF mode: save context and jump to WFI in SDRAM > (omap3_do_wfi) > + * For non-OFF modes: jump to the WFI code in SRAM > (omap3_do_wfi_sram) Why is this distinction? For non-low power modes it should be even safer to issue WFI from DDR itself. Do I miss any errata here ? > + */ > + ldr r4, omap3_do_wfi_sram_addr > + ldr r5, [r4] > + cmp r1, #0x0 @ If no context save required, > + bxeq r5 @ jump to the WFI code in SRAM -- 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
