From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Mon, 19 Aug 2024 08:17:04 +0200 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by lore.white.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1sfvhQ-00B9FP-0J for lore@lore.pengutronix.de; Mon, 19 Aug 2024 08:17:04 +0200 Received: from bombadil.infradead.org ([2607:7c80:54:3::133]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1sfvhP-0007h9-Ab for lore@pengutronix.de; Mon, 19 Aug 2024 08:17:03 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; 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Mon, 19 Aug 2024 08:16:14 +0200 Received: from [2a0a:edc0:2:b01:1d::c5] (helo=pty.whiteo.stw.pengutronix.de) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1sfvgb-001T0g-Ik; Mon, 19 Aug 2024 08:16:13 +0200 Received: from sha by pty.whiteo.stw.pengutronix.de with local (Exim 4.96) (envelope-from ) id 1sfvgb-00Bfz0-1Y; Mon, 19 Aug 2024 08:16:13 +0200 Date: Mon, 19 Aug 2024 08:16:13 +0200 From: Sascha Hauer To: Ahmad Fatoum Cc: Tomas Marek , barebox@lists.infradead.org Message-ID: References: <20240814092424.39878-1-a.fatoum@pengutronix.de> <20240814092424.39878-5-a.fatoum@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240818_231617_962380_17F39DD1 X-CRM114-Status: GOOD ( 27.06 ) X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:3::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.whiteo.stw.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-5.2 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE, T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: Re: [PATCH 5/6] i2c: efi: avoid 64-bit division X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.whiteo.stw.pengutronix.de) On Thu, Aug 15, 2024 at 08:57:18AM +0200, Ahmad Fatoum wrote: > Hello Tomas, > > On 15.08.24 07:53, Tomas Marek wrote: > > Hello Ahmad, > > > > Thanks for maintenance of the Barebox EFI. > > > > On Wed, Aug 14, 2024 at 11:24:23AM +0200, Ahmad Fatoum wrote: > >> I2C message length is 16 bit, so doing a 64-bit division is overkill. > >> Let's remove the cast and just rely on the usual integer promotion > >> to 32-bit. > >> > >> Cc: Tomas Marek > >> Signed-off-by: Ahmad Fatoum > >> --- > >> drivers/i2c/busses/i2c-efi.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/drivers/i2c/busses/i2c-efi.c b/drivers/i2c/busses/i2c-efi.c > >> index 5f6cc0eed28e..a666a28fab51 100644 > >> --- a/drivers/i2c/busses/i2c-efi.c > >> +++ b/drivers/i2c/busses/i2c-efi.c > >> @@ -114,7 +114,7 @@ static unsigned int efi_i2c_msg_op_cnt(const struct efi_i2c_priv *i2c_priv, > >> > >> max_len = efi_i2c_max_len(i2c_priv, msg); > >> > >> - return ((u64)msg->len + max_len - 1) / max_len; > >> + return (msg->len + max_len - 1) / max_len; > > > > The issue here is that max_len, which represents the MaximumReceiveBytes > > or MaximumTransmitBytes in EFI I2C capabilities, is 32-bit. In some EFI > > implementations (including the one I use), the EFI I2C MaximumReceiveBytes > > and MaximumTransmitBytes are set to the maximum value (0xFFFFFFFF). This > > causes msg->len + max_len - 1 to overflow, leading to an incorrect number > > of returned operations. To address this, the msg->len is extended to 64 bits. > > Thanks for the info. See the patch I just Cc'd you on. > > @Sascha, can you drop this one patch again? Ok, reverted it. Sascha -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |