From mboxrd@z Thu Jan 1 00:00:00 1970 From: santosh.shilimkar@oracle.com (santosh shilimkar) Date: Tue, 3 Nov 2015 08:37:23 -0800 Subject: [PATCH v8 2/2] arm-soc: Add support for arm-based tango4 platforms In-Reply-To: References: <56377E76.2080209@sigmadesigns.com> <56377F09.6050805@sigmadesigns.com> <20151102182615.GI2684@leverpostej> <5637AD74.4080206@oracle.com> <563871A9.7050009@sigmadesigns.com> Message-ID: <5638E2C3.4030402@oracle.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 11/3/2015 2:12 AM, M?ns Rullg?rd wrote: > Marc Gonzalez writes: > >> Santosh Shilimkar wrote: >> >>> Mark Rutland wrote: >>> >>>> We didn't. Having a look just now, the earliest example appears to be >>>> in OMAP4 L2 support patches back in 2009 [1]. I was not able to find a >>>> rationale. >>>> >>>> Given that the MMU is on (and speculative accesses are permitted) I >>>> can't see what the DSB achieves -- it can't quiesce the memory system. >>>> >>>> Santosh, any idea? >>> >>> IIRC, it was requirement from the OMAP ROM code to have a dsb before >>> we call the SMC routine. I can't recollect more than that now. >> >> In that case, shouldn't dsb have been added to the ROM code, >> on the "other side" of the smc, so as to not depend on Linux >> code "getting it right"? > > You're new to this, aren't you? :) > :-) Indeed. ROM code is burned into the chip and can't be changed. Regards, Santosh