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 6E99AC7EE25 for ; Mon, 12 Jun 2023 11:03:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237385AbjFLLDj (ORCPT ); Mon, 12 Jun 2023 07:03:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38108 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237344AbjFLLDW (ORCPT ); Mon, 12 Jun 2023 07:03:22 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CE90E7EC5 for ; Mon, 12 Jun 2023 03:51:07 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 69B0C6251A for ; Mon, 12 Jun 2023 10:51:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4AC00C433AC; Mon, 12 Jun 2023 10:51:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1686567066; bh=ZG5XaFw0OdrhywYJYu1KG5HIMTP9aOTXR3y5qEcgeXQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KoD217TYfwZOeQOveKmkUM/ZVXXDE90cgbZkZvFLMUVX8WOKW4wgxm07UMqgfXTD8 0bdMDINNCufVcwIIGfN4SaMmVQR47b8mLpilFKFrBtIHqqEmnd3V892tQ9e+KQg2EF JYoYFtXCnd9VOkyixnP39aBaft+ZmvwXHuToJS2c= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Marek=20Beh=C3=BAn?= , Wolfram Sang , Sasha Levin Subject: [PATCH 6.3 137/160] i2c: mv64xxx: Fix reading invalid status value in atomic mode Date: Mon, 12 Jun 2023 12:27:49 +0200 Message-ID: <20230612101721.336588957@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230612101715.129581706@linuxfoundation.org> References: <20230612101715.129581706@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Marek Behún [ Upstream commit 5578d0a79b6430fa1543640dd6f2d397d0886ce7 ] There seems to be a bug within the mv64xxx I2C controller, wherein the status register may not necessarily contain valid value immediately after the IFLG flag is set in the control register. My theory is that the controller: - first sets the IFLG in control register - then updates the status register - then raises an interrupt This may sometime cause weird bugs when in atomic mode, since in this mode we do not wait for an interrupt, but instead we poll the control register for IFLG and read status register immediately after. I encountered -ENXIO from mv64xxx_i2c_fsm() due to this issue when using this driver in atomic mode. Note that I've only seen this issue on Armada 385, I don't know whether other SOCs with this controller are also affected. Also note that this fix has been in U-Boot for over 4 years [1] without anybody complaining, so it should not cause regressions. [1] https://source.denx.de/u-boot/u-boot/-/commit/d50e29662f78 Fixes: 544a8d75f3d6 ("i2c: mv64xxx: Add atomic_xfer method to driver") Signed-off-by: Marek Behún Signed-off-by: Wolfram Sang Signed-off-by: Sasha Levin --- drivers/i2c/busses/i2c-mv64xxx.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c index 047dfef7a6577..878c076ebdc6b 100644 --- a/drivers/i2c/busses/i2c-mv64xxx.c +++ b/drivers/i2c/busses/i2c-mv64xxx.c @@ -520,6 +520,17 @@ mv64xxx_i2c_intr(int irq, void *dev_id) while (readl(drv_data->reg_base + drv_data->reg_offsets.control) & MV64XXX_I2C_REG_CONTROL_IFLG) { + /* + * It seems that sometime the controller updates the status + * register only after it asserts IFLG in control register. + * This may result in weird bugs when in atomic mode. A delay + * of 100 ns before reading the status register solves this + * issue. This bug does not seem to appear when using + * interrupts. + */ + if (drv_data->atomic) + ndelay(100); + status = readl(drv_data->reg_base + drv_data->reg_offsets.status); mv64xxx_i2c_fsm(drv_data, status); mv64xxx_i2c_do_action(drv_data); -- 2.39.2