From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH] ARM: OMAP: Use ARM SMC Calling Convention when OP-TEE is available Date: Tue, 19 Nov 2019 11:07:21 -0800 Message-ID: <20191119190721.GO35479@atomide.com> References: <20191118223128.GE35479@atomide.com> <29db708e-119e-8a89-7d43-e38e2a10dc07@ti.com> <20191119162157.GJ35479@atomide.com> <6e009ae3-6aa2-409b-749f-4947303940d8@ti.com> <20191119164227.GL35479@atomide.com> <20191119180546.GM35479@atomide.com> <9e15c170-c9fa-778c-d998-bd1111a6390d@ti.com> <20191119183247.GN35479@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: "Andrew F. Davis" Cc: Mark Rutland , linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-omap@vger.kernel.org * Andrew F. Davis [191119 18:51]: > On 11/19/19 1:32 PM, Tony Lindgren wrote: > > It would allow us to completely change over to using > > arm_smccc_smc() and forget the custom calls. > > We would need more than just the r12 quirk to replace all our custom SMC > handlers, we would need quirks for omap_smc2 which puts process ID in r1 > and puts #0xff in r6, and omap_smc3 that uses smc #1. All of our legacy > SMC calls also trash r4-r11, that is very non SMCCC complaint as only > r4-r7 need be caller saved. I don't see arm_smccc_smc() working with > legacy ROM no matter how much we hack at it :( We would just have omap_smc2() call arm_smccc_smc() and in that case. And omap_smc2() would still deal with saving and restoring the registers. Certainly the wrapper functions calling arm_smccc_smc() can deal with r12 too if the r12-quirk version and the plain version are never needed the same time on a booted SoC. Are they ever needed the same time on a booted SoC or not? > I can make OP-TEE also compatible with the r12 quirk, which is what I > used to do. That way we didn't need to do any detection. The issue was > that non-standard SMC calls should not go through the common SMCCC > handler (unless you are QCOM for some reason..). Sounds like for optee nothing must be done for r12 :) Regards, Tony