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 2C64CC433EF for ; Mon, 31 Jan 2022 11:41:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378014AbiAaLlm (ORCPT ); Mon, 31 Jan 2022 06:41:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48964 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1377592AbiAaL1B (ORCPT ); Mon, 31 Jan 2022 06:27:01 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2296EC03327E; Mon, 31 Jan 2022 03:16:33 -0800 (PST) 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 B5E54611DB; Mon, 31 Jan 2022 11:16:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF441C340EE; Mon, 31 Jan 2022 11:16:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643627792; bh=Ii7bXh798F+1fkbQs8ohe5qE2OvgUqgwk72WPGEicF8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=evc/tphnmuIlq5A5xA/XnsP8Rcq7dUpTEfw5CUVwe3w2MKXLTBwGdJalZiE6olhRa nkdTU3dU1WWUaOpgwReTJ+L7ljyyWgfPh9Q8pMl6hcwAZ4rE688ac3Oq4AHqMKvRhP +WqBph+wQE8LJZ4uXfRKqWwSkHGqW/6pV2lEVBVw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Matt Kline , Chandrasekar Ramakrishnan , Michael Anochin , Marc Kleine-Budde Subject: [PATCH 5.16 009/200] can: m_can: m_can_fifo_{read,write}: dont read or write from/to FIFO if length is 0 Date: Mon, 31 Jan 2022 11:54:32 +0100 Message-Id: <20220131105233.868161646@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220131105233.561926043@linuxfoundation.org> References: <20220131105233.561926043@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Marc Kleine-Budde commit db72589c49fd260bfc99c7160c079675bc7417af upstream. 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") Link: https://lore.kernel.org/all/20220114155751.2651888-1-mkl@pengutronix.de Cc: stable@vger.kernel.org Cc: Matt Kline Cc: Chandrasekar Ramakrishnan Reported-by: Michael Anochin Signed-off-by: Marc Kleine-Budde Signed-off-by: Greg Kroah-Hartman --- drivers/net/can/m_can/m_can.c | 6 ++++++ 1 file changed, 6 insertions(+) --- 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 *c 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 * 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); }