From patchwork Fri Dec 6 19:50:55 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Loehle X-Patchwork-Id: 13897669 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E1163E77173 for ; Fri, 6 Dec 2024 19:52:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Subject:From:Cc:To:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=XTCMIYGyOvF6RzUhJ2UadkjOafGsVcD3vQTuCKXf/t0=; b=YtiYZIwI1H1Z7p QsL4vfajbFycz9vcyYLxB7TzqnlGT+HM9DNmQIckibK09ijVQ9LEK/TPgZSn64InXKCVuxiwKgPIA U1VRhes97Q/7iHduawnf/NL2ek4aSPlOpawsW1zLdPvSaOaX6OTvd3XdQlVSBjryfrEYre8esi1bZ JdM5hI10vAG04+J/UbmVTAD9f8Ox91yk47CPmCoT2fiUh3fB4gXeGyiRIWuiu4iTwWhoFX/K7ql4u TF7+A/K7iBcqXkWDd6yeH5f/u4Ry4i7hrGPASuB4gQ/7hX8zuABmTK1Hl5UyiTxjpFWelYYPWxxrW QoXQo3JwtAYeR0R97teg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tJeNL-00000002bUu-35Iz; Fri, 06 Dec 2024 19:52:31 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tJeLu-00000002bIQ-07RU; Fri, 06 Dec 2024 19:51:03 +0000 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 DE32B12FC; Fri, 6 Dec 2024 11:51:26 -0800 (PST) Received: from [192.168.0.16] (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4CF733F58B; Fri, 6 Dec 2024 11:50:57 -0800 (PST) Message-ID: <1f2b3af4-2b7a-4ac8-ab95-c80120ebf44c@arm.com> Date: Fri, 6 Dec 2024 19:50:55 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Content-Language: en-US To: Mark Brown , heiko@sntech.de, luis.dearquer@inertim.com Cc: linux-spi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, "linux-kernel@vger.kernel.org" From: Christian Loehle Subject: [PATCH] spi: rockchip: Fix PM runtime count on no-op cs X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241206_115102_115405_9B0E1E83 X-CRM114-Status: GOOD ( 12.28 ) X-BeenThere: linux-rockchip@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Upstream kernel work for Rockchip platforms List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-rockchip" Errors-To: linux-rockchip-bounces+linux-rockchip=archiver.kernel.org@lists.infradead.org The early bail out that caused an out-of-bounds write was removed with commit 5c018e378f91 ("spi: spi-rockchip: Fix out of bounds array access") Unfortunately that caused the PM runtime count to be unbalanced and underflowed on the first call. To fix that reintroduce a no-op check by reading the register directly. Cc: stable@vger.kernel.org Fixes: 5c018e378f91 ("spi: spi-rockchip: Fix out of bounds array access") Signed-off-by: Christian Loehle --- Not particularly happy with it, it's just the most straightforward fix for the issue at hand. I couldn't quite convince myself that no-op rockchip_spi_set_cs() are 100% ruled out just from spi.c after the first call either, but maybe someone more familiar with the code can. I have only seen the issue for the first call / during boot FWIW. Any more elegant fix suggestions welcome! The other host controller drivers don't need the read before CS change, so this shouldn't really either. drivers/spi/spi-rockchip.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c index 864e58167417..1bc012fce7cb 100644 --- a/drivers/spi/spi-rockchip.c +++ b/drivers/spi/spi-rockchip.c @@ -241,6 +241,20 @@ static void rockchip_spi_set_cs(struct spi_device *spi, bool enable) struct spi_controller *ctlr = spi->controller; struct rockchip_spi *rs = spi_controller_get_devdata(ctlr); bool cs_asserted = spi->mode & SPI_CS_HIGH ? enable : !enable; + bool cs_actual; + + /* + * SPI subsystem tries to avoid no-op calls that would break the PM + * refcount below. It can't however for the first time it is used. + * To detect this case we read it here and bail out early for no-ops. + */ + if (spi_get_csgpiod(spi, 0)) + cs_actual = !!(readl_relaxed(rs->regs + ROCKCHIP_SPI_SER) & 1); + else + cs_actual = !!(readl_relaxed(rs->regs + ROCKCHIP_SPI_SER) & + BIT(spi_get_chipselect(spi, 0))); + if (unlikely(cs_actual == cs_asserted)) + return; if (cs_asserted) { /* Keep things powered as long as CS is asserted */