Vishwanath BS <vishwanath.bs@xxxxxx> writes: > This patch adds comments on precatution to be taken if Global SW reset is > used as the means to trigger sysem reset. > > Signed-off-by: Vishwanath BS <vishwanath.bs@xxxxxx> > Cc: Paul Walmsley <paul@xxxxxxxxx> Please fix multi-line comment style. Search for 'multi-line' in Documentation/CodingStyle Kevin > --- > arch/arm/mach-omap2/prcm.c | 26 ++++++++++++++++++++++++++ > 1 files changed, 26 insertions(+), 0 deletions(-) > > diff --git a/arch/arm/mach-omap2/prcm.c b/arch/arm/mach-omap2/prcm.c > index c201374..fdc860e > --- a/arch/arm/mach-omap2/prcm.c > +++ b/arch/arm/mach-omap2/prcm.c > @@ -157,6 +157,32 @@ void omap_prcm_arch_reset(char mode, const char *cmd) > else > WARN_ON(1); > > + /* As per Errata i520, In some cases, user > + * will not be able to access DDR memory after warm-reset. > + * This situation occurs while the warm-reset happens during a read > + * access to DDR memory. In that particular condition, DDR memory > + * does not respond to a corrupted read command due to the warm > + * reset occurence but SDRC is waiting for read completion. > + * SDRC is not sensitive to the warm reset, but the interconect is > + * reset on the fly, thus causing a misalignment between SDRC logic, > + * interconect logic and DDR memory state. > + * WORKAROUND: > + * Steps to perform before a Warm reset is trigged: > + * 1. enable self-refresh on idle request > + * 2. put SDRC in idle > + * 3. wait until SDRC goes to idle > + * 4. generate SW reset (Global SW reset) > + > + * Steps to be performed after warm reset occurs (in bootloader): > + * if HW warm reset is the source, apply below steps before any > + * accesses to SDRAM: > + * 1. Reset SMS and SDRC and wait till reset is complete > + * 2. Re-initialize SMS, SDRC and memory > + > + * NOTE: Above work around is required only if arch reset is implemented > + * using Global SW reset(GLOBAL_SW_RST). DPLL3 reset does not need > + * the WA since it resets SDRC as well as part of cold reset. */ > + > if (cpu_is_omap24xx() || cpu_is_omap34xx()) > prm_set_mod_reg_bits(OMAP_RST_DPLL3_MASK, prcm_offs, > OMAP2_RM_RSTCTRL); -- 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
