> -----Original Message----- > From: York Sun [mailto:[email protected]] > Sent: Thursday, November 05, 2015 9:38 AM > To: Kushwaha Prabhakar-B32579 <[email protected]>; u- > [email protected] > Subject: Re: [PATCH][v2] armv8: ls2085a: Add workaround of errata A009635 > > > > On 11/04/2015 07:58 PM, Kushwaha Prabhakar-B32579 wrote: > > > >> -----Original Message----- > >> From: York Sun [mailto:[email protected]] > >> Sent: Thursday, November 05, 2015 12:27 AM > >> To: Kushwaha Prabhakar-B32579 <[email protected]>; u- > >> [email protected] > >> Subject: Re: [PATCH][v2] armv8: ls2085a: Add workaround of errata > >> A009635 > >> > >> > >> > >> On 11/03/2015 11:24 PM, Prabhakar Kushwaha wrote: > >>> If the core runs at higher than x3 speed of the platform, there is > >>> possiblity about sev instruction to getting missed by other cores. > >>> This is because of SoC Run Control block may not able to sample the > >>> EVENTI(Sev) signals. > >>> > >>> Configure Run Control and EPU to periodically send out EVENTI > >>> signals to wake up A57 cores. > >>> > >>> Signed-off-by: Prabhakar Kushwaha <[email protected]> > >>> --- > >>> Chages for v2: Updated description > >>> > >>> arch/arm/cpu/armv8/fsl-layerscape/cpu.c | 6 ++++ > >>> arch/arm/cpu/armv8/fsl-layerscape/soc.c | 39 > >> +++++++++++++++++++++++ > >>> arch/arm/include/asm/arch-fsl-layerscape/config.h | 9 ++++++ > >>> arch/arm/include/asm/arch-fsl-layerscape/soc.h | 3 ++ > >>> 4 files changed, 57 insertions(+) > >>> > >>> diff --git a/arch/arm/cpu/armv8/fsl-layerscape/cpu.c > >>> b/arch/arm/cpu/armv8/fsl-layerscape/cpu.c > >>> index 0cb0afa..dbb12c2 100644 > >>> --- a/arch/arm/cpu/armv8/fsl-layerscape/cpu.c > >>> +++ b/arch/arm/cpu/armv8/fsl-layerscape/cpu.c > >>> @@ -484,7 +484,13 @@ int arch_early_init_r(void) { #ifdef CONFIG_MP > >>> int rv = 1; > >>> +#endif > >>> + > >>> +#ifdef CONFIG_SYS_FSL_ERRATUM_A009635 > >>> + erratum_a009635(); > >>> +#endif > >>> > >>> +#ifdef CONFIG_MP > >>> rv = fsl_layerscape_wake_seconday_cores(); > >>> if (rv) > >>> printf("Did not wake secondary cores\n"); diff --git > >>> a/arch/arm/cpu/armv8/fsl-layerscape/soc.c > >> b/arch/arm/cpu/armv8/fsl-layerscape/soc.c > >>> index 637853d..e8cdb10 100644 > >>> --- a/arch/arm/cpu/armv8/fsl-layerscape/soc.c > >>> +++ b/arch/arm/cpu/armv8/fsl-layerscape/soc.c > >>> @@ -9,10 +9,49 @@ > >>> #include <asm/arch/soc.h> > >>> #include <asm/io.h> > >>> #include <asm/global_data.h> > >>> +#include <asm/arch-fsl-layerscape/config.h> > >>> > >>> DECLARE_GLOBAL_DATA_PTR; > >>> > >>> #ifdef CONFIG_LS2085A > >>> +#ifdef CONFIG_SYS_FSL_ERRATUM_A009635 > >>> +#define PLATFORM_CYCLE_ENV_VAR "a009635_interval_val" > >>> + > >>> +static unsigned long get_internval_val_mhz(void) { > >>> + char *interval = getenv(PLATFORM_CYCLE_ENV_VAR); > >> > >> Why do you need a variable to override the calculation? > >> > > > > Following needs to be supported as part of errata workaround 1. > > Ability to modify platform clock value to increase time interval 2. > > Disable workaround in platform clock 0 > > > > As per Errata workaround, > > "For <interval> value above, it is the number of platform cycles between > wake up events generated by EPU. For example: > > A typical value is 1 microsecond. If the platform frequency is 500MHz, each > cycle is 2ns. interval = 1us/2ns=500=0x1F4." > > This is taken care of by the formula. Is there any need to adjust the time > interval? If you do, you are risking of running too fast or too slow.
Yes, customer may like to increase or decrease the time interval to fine tune the system behavior. > If setting > the variable as 0, does it have the same effect as not running this > workaround? Yes, setting 0 == Not running WA. I verified it. > If this is a debug technique, please remove if not required by the > workaround. This problem occur when core clock is > 2.5.x of platform clock. If anyone using core clock < 2.5x of platform clock, this workaround is not required. > If you really want to support override, please add a comment inline and in > commit message. OK > > > > >> > >>> + ulong interval_mhz = get_bus_freq(0) / (1000 * 1000); > >> > >> Please add a comment here to explain what the interval does and why > >> it is calculated this way. > >> > > > > Sure, > > York _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
