From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6039AC4167B for ; Fri, 1 Dec 2023 16:18:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235323AbjLAQSj (ORCPT ); Fri, 1 Dec 2023 11:18:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40062 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1378508AbjLAQR5 (ORCPT ); Fri, 1 Dec 2023 11:17:57 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 3CCF11BC5; Fri, 1 Dec 2023 08:18:00 -0800 (PST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6408A1007; Fri, 1 Dec 2023 08:18:46 -0800 (PST) Received: from pluto (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C4F043F6C4; Fri, 1 Dec 2023 08:17:58 -0800 (PST) Date: Fri, 1 Dec 2023 16:17:56 +0000 From: Cristian Marussi To: Sudeep Holla Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, quic_mdtipton@quicinc.com, quic_asartor@quicinc.com, quic_lingutla@quicinc.com, Sibi Sankar , linux-arm-msm@vger.kernel.org Subject: Re: [PATCH 1/2] firmware: arm_scmi: Fix frequency truncation by promoting multiplier to u64 Message-ID: References: <20231130204343.503076-1-sudeep.holla@arm.com> <20231201143935.be6wzjzxmyl5vpz6@bogus> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231201143935.be6wzjzxmyl5vpz6@bogus> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 01, 2023 at 02:39:35PM +0000, Sudeep Holla wrote: > On Thu, Nov 30, 2023 at 08:43:42PM +0000, Sudeep Holla wrote: > > Fix the frequency truncation for all values equal to or greater 4GHz by > > updating the multiplier 'mult_factor' to u64 type. It is also possible > > that the multiplier itself can be greater than or equal to 2^32. So we need > > to also fix the equation computing the value of the multiplier. > > > > Fixes: a9e3fbfaa0ff ("firmware: arm_scmi: add initial support for performance protocol") > > Reported-by: Sibi Sankar > > Closes: https://lore.kernel.org/all/20231129065748.19871-3-quic_sibis@quicinc.com/ > > Cc: Cristian Marussi > > Signed-off-by: Sudeep Holla > > --- > > drivers/firmware/arm_scmi/perf.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c > > index 81dd5c5e5533..8ce449922e55 100644 > > --- a/drivers/firmware/arm_scmi/perf.c > > +++ b/drivers/firmware/arm_scmi/perf.c > > @@ -152,7 +152,7 @@ struct perf_dom_info { > > u32 opp_count; > > u32 sustained_freq_khz; > > u32 sustained_perf_level; > > - u32 mult_factor; > > + u64 mult_factor; > > I have now changed this to unsigned long instead of u64 to fix the 32-bit > build failure[1]. Right, I was caught a few times too by this kind of failures on v7 :D ... but this 32bit issue makes me wonder what to do in such a case... ...I mean, on 32bit if the calculated freq oveflows, there is just nothing we can do on v7 without overcomplicating the code...but I suppose it is unplausible to have such high freq on a v7... as a palliative I can only think of some sort of overflow check (only on v7) that could trigger a warning ... but it is hardly worth the effort probably.. Thanks, Cristian