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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 47B8AC33CB6 for ; Thu, 16 Jan 2020 17:54:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 236DE2077C for ; Thu, 16 Jan 2020 17:54:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579197294; bh=JjKzewG3WJ8YyYk2XXWWjPF7f9+Ifwp2QYTgE0cFhk4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=IX8hDl+CYvwx2P7oZI+mn6IuDzChM+wCXMX3QguWnWX+lkPRKdfcjsLmPiNBxr9// FGMtRZ128okhFub3LIR4uYHGMn1yH8/coSVkcxH2kbRC6fDHgTLVV2CUPEsSudmibT ZgrS9Cvg/CDO+DAnQz/hpzYT+wsjesmUtMbp+F38= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2394182AbgAPRob (ORCPT ); Thu, 16 Jan 2020 12:44:31 -0500 Received: from mail.kernel.org ([198.145.29.99]:35530 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2394179AbgAPRob (ORCPT ); Thu, 16 Jan 2020 12:44:31 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 86B8324748; Thu, 16 Jan 2020 17:44:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579196670; bh=JjKzewG3WJ8YyYk2XXWWjPF7f9+Ifwp2QYTgE0cFhk4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ELPkryr8XSZsHWx0EkxisEGKvWIspNl2fEr6H5nTGcLgY0hHECqFlLIuPiVhKSxBd c4eTCwRAqsykijife9Srcgr3wLRJ19akgjRV1kWnnPp0ea/nUn5feK3N+LKxWQZjzc KpndDoIs19llyYxKAf15aJRa8xuWBvyj/0h4Ge+g= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Martin Sperl , Stefan Wahren , Mark Brown , Sasha Levin , linux-spi@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH AUTOSEL 4.4 071/174] spi: bcm2835aux: fix driver to not allow 65535 (=-1) cs-gpios Date: Thu, 16 Jan 2020 12:41:08 -0500 Message-Id: <20200116174251.24326-71-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200116174251.24326-1-sashal@kernel.org> References: <20200116174251.24326-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Martin Sperl [ Upstream commit 509c583620e9053e43d611bf1614fc3d3abafa96 ] The original driver by default defines num_chipselects as -1. This actually allicates an array of 65535 entries in of_spi_register_master. There is a side-effect for buggy device trees that (contrary to dt-binding documentation) have no cs-gpio defined. This mode was never supported by the driver due to limitations of native cs and additional code complexity and is explicitly not stated to be implemented. To keep backwards compatibility with such buggy DTs we limit the number of chip_selects to 1, as for all practical purposes it is only ever realistic to use a single chip select in native cs mode without negative side-effects. Fixes: 1ea29b39f4c812ec ("spi: bcm2835aux: add bcm2835 auxiliary spi device...") Signed-off-by: Martin Sperl Acked-by: Stefan Wahren Signed-off-by: Mark Brown Signed-off-by: Sasha Levin --- drivers/spi/spi-bcm2835aux.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c index ca655593c5e0..1cedd640705f 100644 --- a/drivers/spi/spi-bcm2835aux.c +++ b/drivers/spi/spi-bcm2835aux.c @@ -390,7 +390,18 @@ static int bcm2835aux_spi_probe(struct platform_device *pdev) platform_set_drvdata(pdev, master); master->mode_bits = BCM2835_AUX_SPI_MODE_BITS; master->bits_per_word_mask = SPI_BPW_MASK(8); - master->num_chipselect = -1; + /* even though the driver never officially supported native CS + * allow a single native CS for legacy DT support purposes when + * no cs-gpio is configured. + * Known limitations for native cs are: + * * multiple chip-selects: cs0-cs2 are all simultaniously asserted + * whenever there is a transfer - this even includes SPI_NO_CS + * * SPI_CS_HIGH: is ignores - cs are always asserted low + * * cs_change: cs is deasserted after each spi_transfer + * * cs_delay_usec: cs is always deasserted one SCK cycle after + * a spi_transfer + */ + master->num_chipselect = 1; master->transfer_one = bcm2835aux_spi_transfer_one; master->handle_err = bcm2835aux_spi_handle_err; master->dev.of_node = pdev->dev.of_node; -- 2.20.1