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 BBBF4C433F5 for ; Fri, 14 Jan 2022 16:04:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239094AbiANQEz (ORCPT ); Fri, 14 Jan 2022 11:04:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45142 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238931AbiANQEz (ORCPT ); Fri, 14 Jan 2022 11:04:55 -0500 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF725C061574 for ; Fri, 14 Jan 2022 08:04:54 -0800 (PST) Received: from gallifrey.ext.pengutronix.de ([2001:67c:670:201:5054:ff:fe8d:eefb] helo=bjornoya.blackshift.org) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1n8P4P-0006M1-9h for linux-can@vger.kernel.org; Fri, 14 Jan 2022 17:04:53 +0100 Received: from dspam.blackshift.org (localhost [127.0.0.1]) by bjornoya.blackshift.org (Postfix) with SMTP id CF1EF18C10 for ; Fri, 14 Jan 2022 16:04:52 +0000 (UTC) Received: from hardanger.blackshift.org (unknown [172.20.34.65]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by bjornoya.blackshift.org (Postfix) with ESMTPS id A78ED18C07; Fri, 14 Jan 2022 16:04:52 +0000 (UTC) Received: from blackshift.org (localhost [::1]) by hardanger.blackshift.org (OpenSMTPD) with ESMTP id 2344bd82; Fri, 14 Jan 2022 15:31:31 +0000 (UTC) From: Marc Kleine-Budde To: linux-can@vger.kernel.org Cc: Marc Kleine-Budde , stable@vger.kernel.org, Matt Kline , Chandrasekar Ramakrishnan , Michael Anochin Subject: [PATCH] can: m_can: m_can_fifo_{read,write}: don't read or write from/to FIFO if length is 0 Date: Fri, 14 Jan 2022 16:31:30 +0100 Message-Id: <20220114153130.2647738-1-mkl@pengutronix.de> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 2001:67c:670:201:5054:ff:fe8d:eefb X-SA-Exim-Mail-From: mkl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-can@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-can@vger.kernel.org In order to optimize FIFO access, especially on m_can cores attached to slow busses like SPI, in patch | e39381770ec9 ("can: m_can: Disable IRQs on FIFO bus errors") bulk read/write support has been added to the m_can_fifo_{read,write} functions. That change leads to the tcan driver to call regmap_bulk_{read,write}() with a length of 0 (for CAN frames with 0 data length). regmap treats this as an error: | tcan4x5x spi1.0 tcan4x5x0: FIFO write returned -22 This patch fixes the problem by not calling the cdev->ops->{read,write)_fifo() in case of a 0 length read/write. Fixes: e39381770ec9 ("can: m_can: Disable IRQs on FIFO bus errors") Cc: stable@vger.kernel.org Cc: Matt Kline Cc: Chandrasekar Ramakrishnan Reported-by: Michael Anochin Signed-off-by: Marc Kleine-Budde --- drivers/net/can/m_can/m_can.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c index 5b47cd867783..1a4b56f6fa8c 100644 --- a/drivers/net/can/m_can/m_can.c +++ b/drivers/net/can/m_can/m_can.c @@ -336,6 +336,9 @@ m_can_fifo_read(struct m_can_classdev *cdev, u32 addr_offset = cdev->mcfg[MRAM_RXF0].off + fgi * RXF0_ELEMENT_SIZE + offset; + if (val_count == 0) + return 0; + return cdev->ops->read_fifo(cdev, addr_offset, val, val_count); } @@ -346,6 +349,9 @@ m_can_fifo_write(struct m_can_classdev *cdev, u32 addr_offset = cdev->mcfg[MRAM_TXB].off + fpi * TXB_ELEMENT_SIZE + offset; + if (val_count == 0) + return 0; + return cdev->ops->write_fifo(cdev, addr_offset, val, val_count); } -- 2.34.1