From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH v2 2/5] ARM: shmobile: r8a7740: Migrate to generic l2c OF initialization Date: Wed, 04 Feb 2015 19:33:31 +0100 Message-ID: <2328848.sGW6KXzxun@wuerfel> References: <1423059315-28519-1-git-send-email-geert+renesas@glider.be> <3598552.qKIyokxIlF@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org Cc: Geert Uytterhoeven , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Geert Uytterhoeven , Linux-sh list , Magnus Damm , Russell King , Simon Horman List-Id: devicetree@vger.kernel.org On Wednesday 04 February 2015 18:04:57 Geert Uytterhoeven wrote: > On Wed, Feb 4, 2015 at 5:36 PM, Arnd Bergmann wrote: > > On Wednesday 04 February 2015 15:43:43 Geert Uytterhoeven wrote: > >> > >> Indeed. Note that I only try to preserve the register value before and after > >> migrating to generic l2c OF initialization. I did read (part of) the pl310 > >> documentation, but it's still not clear to me if we really need > >> L2C_AUX_CTRL_SHARED_OVERRIDE. Perhaps this was just copied from > >> somewhere else without much afterthought? > > > > Have you checked what the hardware/bootloader actually sets in that bit? > > Yes, it boots with 0x02040000, i.e. L2C_AUX_CTRL_SHARED_OVERRIDE > (bit 22) is not set. > > After the l2c driver is finished with it, it contains 0x46440001. I see. I guess someone understand the effect of this flag. Does it make a difference on the machine you are looking at? I've read the spec at http://infocenter.arm.com/help/topic/com.arm.doc.ddi0246a/DDI0246A_l2cc_pl310_r0p0_trm.pdf on the topic but couldn't make sense of it to understand whether a particular setting might be required for specific hardware or might be a performance optimization. Arnd -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html