Am Montag, den 30.11.2015, 20:27 +0200 schrieb Grygorii Strashko: > On 11/30/2015 07:27 PM, Lucas Stach wrote: > > Am Montag, den 16.11.2015, 14:24 +0200 schrieb Grygorii Strashko: > >> On 11/16/2015 01:25 PM, Lucas Stach wrote: > >>> omap_interconnect_sync() is the only user of the SRAM scratch area > >>> allocated in the omap4_sram_init initcall. The interconnect sync is > >>> used exclusively in the OMAP4 specific WFI implementation, so there > >>> is no point in allocating the SRAM scratch on other SoC types. > >>> > >>> Bail out of the initcall if the kernel is not running on OMAP4 to > >>> avoid a confusing warning about being unable to allocate the SRAM > >>> needed for I688 handling. > >>> > >>> Signed-off-by: Lucas Stach <l.st...@pengutronix.de> > >>> Tested-by: Bastian Stender <b...@pengutronix.de> > >>> --- > >>> arch/arm/mach-omap2/omap4-common.c | 3 +++ > >>> 1 file changed, 3 insertions(+) > >>> > >>> diff --git a/arch/arm/mach-omap2/omap4-common.c > >>> b/arch/arm/mach-omap2/omap4-common.c > >>> index 949696b6f17b..6db393a30a28 100644 > >>> --- a/arch/arm/mach-omap2/omap4-common.c > >>> +++ b/arch/arm/mach-omap2/omap4-common.c > >>> @@ -131,6 +131,9 @@ static int __init omap4_sram_init(void) > >>> struct device_node *np; > >>> struct gen_pool *sram_pool; > >>> > >>> + if (!cpu_is_omap44xx()) > >>> + return 0; > >> > >> This one affects on am43xx also > >> > > So you are saying this erratum is also present on AM43xx? I wasn't able > > to deduce this from the information provided by Richard Woodruff. > > > > "..SOCs using similar chassis components of OMAP4430 time are impacted..." > "..But AM335x should be immune from this particular issue..." > > Advisory 11 Asynchronous Bridge Corruption > http://www.ti.com/lit/er/sprz408b/sprz408b.pdf > > Thanks for the link, it makes things a lot more clear. > > >> > >>> + > >>> np = of_find_compatible_node(NULL, NULL, "ti,omap4-mpu"); > >>> if (!np) > >>> pr_warn("%s:Unable to allocate sram needed to handle > >>> errata I688\n", > >> > >> Since all OMAP4+ platforms are now DT based why can't we just return from > >> here silently? > >> > > If we are unable to allocate the SRAM needed to work around I688 this is > > a real error on platforms that expose this erratum, so silently bailing > > out at this point may obscure a real issue. > > > > SRAM is not allocated here - It's just check to understand do we need it or > not > in case of multiplatform build where CONFIG_OMAP_INTERCONNECT_BARRIER will be > selected most > probably. > > And if "ti,omap4-mpu" was not found - it just means that this, particular, > platform > is not affected by i688 errata. > If someone misses corresponding node in DT - we can't do nothing :) > Okay, so the above document says that AM43xx is affected by the erratum, but the am4372.dtsi doesn't contain a "ti,omap4-mpu" node, so the workaround will not be applied. If we silence the warning, we now have a system that will be prone to data corruption without ever warning the user about it. This is surely not what anyone wants.
Regards, Lucas -- Pengutronix e.K. | Lucas Stach | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
