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 X-Spam-Level: X-Spam-Status: No, score=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 93D73C433E0 for ; Wed, 13 Jan 2021 14:34:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 79852229CA for ; Wed, 13 Jan 2021 14:34:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726471AbhAMOeZ (ORCPT ); Wed, 13 Jan 2021 09:34:25 -0500 Received: from gofer.mess.org ([88.97.38.141]:50591 "EHLO gofer.mess.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725843AbhAMOeZ (ORCPT ); Wed, 13 Jan 2021 09:34:25 -0500 Received: by gofer.mess.org (Postfix, from userid 1000) id 62E44C6378; Wed, 13 Jan 2021 14:33:43 +0000 (GMT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=mess.org; s=2020; t=1610548423; bh=mEnNij7JtIsgICbFjxm+XkheIaJlysr8bzezKdXpPkw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=T7WMkVijJRJ16g0Fr2qpEN8GGavduKlAN2AQWhQqh1KOk9KGJ1mIiwLDYEXE8st95 17TgOxns/z69eqWtVXQvo7o9FUDpORK5YHvBs/KloWUCmrlPwKTVMZDBoA8v8vPNro Cd+3K9wPRwQmDQ2v2xOq1Z9zGAp1svJutxlPulMkg+muLzM7AVr9oaiQRBrPGQYMCO c1/nivxi7uKZVd/UUj5lk5ycR4f3N8NkknHm+Y7q63vwEafeUNZoYbYbsnBRXpU+ci Vl/CAJr99jf3x7aEZVtNkugYnOi62ZwgmhAZCztI80fLvIQbMK2WsNHBlSawfM3M2c cJ2uq3zMxEBzw== Date: Wed, 13 Jan 2021 14:33:43 +0000 From: Sean Young To: Samuel Holland Cc: Mauro Carvalho Chehab , Maxime Ripard , Chen-Yu Tsai , Jernej Skrabec , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, linux-sunxi@googlegroups.com Subject: Re: [PATCH 1/4] media: sunxi-cir: Clean up dead register writes Message-ID: <20210113143343.GA8430@gofer.mess.org> References: <20210113045132.31430-1-samuel@sholland.org> <20210113045132.31430-2-samuel@sholland.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210113045132.31430-2-samuel@sholland.org> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 12, 2021 at 10:51:29PM -0600, Samuel Holland wrote: > The register writes during driver removal occur after the device is > already put back in reset, so they never had any effect. > > Signed-off-by: Samuel Holland > --- > drivers/media/rc/sunxi-cir.c | 10 ---------- > 1 file changed, 10 deletions(-) > > diff --git a/drivers/media/rc/sunxi-cir.c b/drivers/media/rc/sunxi-cir.c > index 8555c7798706..0a7f7eab3cc3 100644 > --- a/drivers/media/rc/sunxi-cir.c > +++ b/drivers/media/rc/sunxi-cir.c > @@ -342,22 +342,12 @@ static int sunxi_ir_probe(struct platform_device *pdev) > > static int sunxi_ir_remove(struct platform_device *pdev) > { > - unsigned long flags; > struct sunxi_ir *ir = platform_get_drvdata(pdev); > > clk_disable_unprepare(ir->clk); > clk_disable_unprepare(ir->apb_clk); > reset_control_assert(ir->rst); > > - spin_lock_irqsave(&ir->ir_lock, flags); > - /* disable IR IRQ */ > - writel(0, ir->base + SUNXI_IR_RXINT_REG); > - /* clear All Rx Interrupt Status */ > - writel(REG_RXSTA_CLEARALL, ir->base + SUNXI_IR_RXSTA_REG); > - /* disable IR */ > - writel(0, ir->base + SUNXI_IR_CTL_REG); > - spin_unlock_irqrestore(&ir->ir_lock, flags); > - > rc_unregister_device(ir->rc); > return 0; > } I don't think there is anything wrong with the patch, however here the driver does rc_unregister_device() *after* disabling it. Userspace can still hold a file descriptor open, and call e.g. LIRC_SET_REC_TIMEOUT ioctl, which causes various writes the sunxi-cir registers. The order should be reversed. Sean