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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 41573C433DF for ; Fri, 12 Jun 2020 07:58:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B824207D8 for ; Fri, 12 Jun 2020 07:58:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726397AbgFLH6g (ORCPT ); Fri, 12 Jun 2020 03:58:36 -0400 Received: from alexa-out-sd-02.qualcomm.com ([199.106.114.39]:10922 "EHLO alexa-out-sd-02.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726262AbgFLH6g (ORCPT ); Fri, 12 Jun 2020 03:58:36 -0400 Received: from unknown (HELO ironmsg-SD-alpha.qualcomm.com) ([10.53.140.30]) by alexa-out-sd-02.qualcomm.com with ESMTP; 12 Jun 2020 00:58:25 -0700 Received: from sivaprak-linux.qualcomm.com ([10.201.3.202]) by ironmsg-SD-alpha.qualcomm.com with ESMTP; 12 Jun 2020 00:58:23 -0700 Received: by sivaprak-linux.qualcomm.com (Postfix, from userid 459349) id CE32321880; Fri, 12 Jun 2020 13:28:21 +0530 (IST) From: Sivaprakash Murugesan To: miquel.raynal@bootlin.com, richard@nod.at, vigneshr@ti.com, peter.ujfalusi@ti.com, sivaprak@codeaurora.org, boris.brezillon@collabora.com, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH V4 2/2] mtd: rawnand: qcom: set BAM mode only if not set already Date: Fri, 12 Jun 2020 13:28:16 +0530 Message-Id: <1591948696-16015-3-git-send-email-sivaprak@codeaurora.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1591948696-16015-1-git-send-email-sivaprak@codeaurora.org> References: <1591948696-16015-1-git-send-email-sivaprak@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org BAM is DMA controller on QCOM ipq platforms, BAM mode on NAND driver is set by writing BAM_MODE_EN bit on NAND_CTRL register. NAND_CTRL is an operational register and in BAM mode operational registers are read only. So, before enabling BAM mode by writing the NAND_CTRL register, check if BAM mode was already enabled by the bootloader, and enable BAM mode only if it is not enabled already. Signed-off-by: Sivaprakash Murugesan --- drivers/mtd/nand/raw/qcom_nandc.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/mtd/nand/raw/qcom_nandc.c b/drivers/mtd/nand/raw/qcom_nandc.c index 78b5f21..a3ef428 100644 --- a/drivers/mtd/nand/raw/qcom_nandc.c +++ b/drivers/mtd/nand/raw/qcom_nandc.c @@ -2784,7 +2784,14 @@ static int qcom_nandc_setup(struct qcom_nand_controller *nandc) /* enable ADM or BAM DMA */ if (nandc->props->is_bam) { nand_ctrl = nandc_read(nandc, NAND_CTRL); - nandc_write(nandc, NAND_CTRL, nand_ctrl | BAM_MODE_EN); + /* NAND_CTRL is an operational registers, and CPU + * access to operational registers are read only + * in BAM mode. So update the NAND_CTRL register + * only if it is not in BAM mode. In most cases BAM + * mode will be enabled in bootloader + */ + if (!(nand_ctrl | BAM_MODE_EN)) + nandc_write(nandc, NAND_CTRL, nand_ctrl | BAM_MODE_EN); } else { nandc_write(nandc, NAND_FLASH_CHIP_SELECT, DM_EN); } -- 2.7.4