From patchwork Wed Jan 25 08:10:20 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dhruva Gole X-Patchwork-Id: 13115086 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 6C4B8C54E94 for ; Wed, 25 Jan 2023 08:11:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234059AbjAYILN (ORCPT ); Wed, 25 Jan 2023 03:11:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50312 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232745AbjAYILM (ORCPT ); Wed, 25 Jan 2023 03:11:12 -0500 Received: from lelv0143.ext.ti.com (lelv0143.ext.ti.com [198.47.23.248]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 81AA346733; Wed, 25 Jan 2023 00:11:10 -0800 (PST) Received: from lelv0266.itg.ti.com ([10.180.67.225]) by lelv0143.ext.ti.com (8.15.2/8.15.2) with ESMTP id 30P8As6I011847; Wed, 25 Jan 2023 02:10:54 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1674634254; bh=eNbchGJC+m7Z4S8cdQhmzaRMkS8co3zGkOBT6wpgpHk=; h=From:To:CC:Subject:Date:In-Reply-To:References; b=j7gB/YsZlksX1b4LpewIFD5sKJil4cqsuQtgAiuJkS29kXj67YzEKnfLj+gEuVefd tpNf+27cln3H9Mvu+IH8mRrwlIGgBNWT4Ydbap5Fu03gL1UL+QZ2uHAstWTbCyTLZZ qeFjZX3mZXLkD6VNnSexFwvKxtMTiL7W63uV0vJY= Received: from DFLE114.ent.ti.com (dfle114.ent.ti.com [10.64.6.35]) by lelv0266.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 30P8AsLI124978 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 25 Jan 2023 02:10:54 -0600 Received: from DFLE110.ent.ti.com (10.64.6.31) by DFLE114.ent.ti.com (10.64.6.35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.16; Wed, 25 Jan 2023 02:10:53 -0600 Received: from fllv0039.itg.ti.com (10.64.41.19) by DFLE110.ent.ti.com (10.64.6.31) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.16 via Frontend Transport; Wed, 25 Jan 2023 02:10:53 -0600 Received: from localhost (ileaxei01-snat2.itg.ti.com [10.180.69.6]) by fllv0039.itg.ti.com (8.15.2/8.15.2) with ESMTP id 30P8Aqag075469; Wed, 25 Jan 2023 02:10:53 -0600 From: Dhruva Gole To: Mark Brown CC: , , Vignesh Raghavendra , Vaishnav Achath , Dhruva Gole , , , , Pratyush Yadav Subject: [PATCH v2 1/4] spi: cadence-quadspi: Reset CMD_CTRL Reg on cmd r/w completion Date: Wed, 25 Jan 2023 13:40:20 +0530 Message-ID: <20230125081023.1573712-2-d-gole@ti.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230125081023.1573712-1-d-gole@ti.com> References: <20230125081023.1573712-1-d-gole@ti.com> MIME-Version: 1.0 X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org If one leaves the CQSPI_REG_CMDCTRL in an unclean state this may cause issues in future command reads. This issue came to light when some flash reads in STIG mode were coming back dirty. Signed-off-by: Dhruva Gole --- drivers/spi/spi-cadence-quadspi.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) -- 2.25.1 diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c index 676313e1bdad..6030da942c6e 100644 --- a/drivers/spi/spi-cadence-quadspi.c +++ b/drivers/spi/spi-cadence-quadspi.c @@ -549,6 +549,9 @@ static int cqspi_command_read(struct cqspi_flash_pdata *f_pdata, memcpy(rxbuf, ®, read_len); } + /* Reset CMD_CTRL Reg once command read completes */ + writel(0, reg_base + CQSPI_REG_CMDCTRL); + return 0; } @@ -613,7 +616,12 @@ static int cqspi_command_write(struct cqspi_flash_pdata *f_pdata, } } - return cqspi_exec_flash_cmd(cqspi, reg); + ret = cqspi_exec_flash_cmd(cqspi, reg); + + /* Reset CMD_CTRL Reg once command write completes */ + writel(0, reg_base + CQSPI_REG_CMDCTRL); + + return ret; } static int cqspi_read_setup(struct cqspi_flash_pdata *f_pdata, From patchwork Wed Jan 25 08:10:21 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dhruva Gole X-Patchwork-Id: 13115087 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 1C5AAC54EED for ; Wed, 25 Jan 2023 08:11:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234770AbjAYILO (ORCPT ); Wed, 25 Jan 2023 03:11:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50324 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234627AbjAYILN (ORCPT ); Wed, 25 Jan 2023 03:11:13 -0500 Received: from fllv0015.ext.ti.com (fllv0015.ext.ti.com [198.47.19.141]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 22F3B4709B; Wed, 25 Jan 2023 00:11:12 -0800 (PST) Received: from lelv0265.itg.ti.com ([10.180.67.224]) by fllv0015.ext.ti.com (8.15.2/8.15.2) with ESMTP id 30P8Axjh100110; Wed, 25 Jan 2023 02:10:59 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1674634259; bh=jJEIxkjBuCyQ2kRnrK0zrFDRWiVOz4giHjGrLWfCLP8=; h=From:To:CC:Subject:Date:In-Reply-To:References; b=Bxb/TfHtczeBJO1G9NyNjHiXwFWGiFv1R+tMxcfyxWkOtJXoOrA2iJ8GJ2xxgiqWW 3YakzbG0LKPOrRlvWVtSkOWzKED0JlVE8R9uLwuCY6iT+jKp5TnDaWaohOmKuTZ6dD HBluk+cp/NPJVlvX0/7KOT8evurI37h89CDUxh7s= Received: from DFLE114.ent.ti.com (dfle114.ent.ti.com [10.64.6.35]) by lelv0265.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 30P8Ax9L027212 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 25 Jan 2023 02:10:59 -0600 Received: from DFLE109.ent.ti.com (10.64.6.30) by DFLE114.ent.ti.com (10.64.6.35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.16; Wed, 25 Jan 2023 02:10:59 -0600 Received: from lelv0327.itg.ti.com (10.180.67.183) by DFLE109.ent.ti.com (10.64.6.30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.16 via Frontend Transport; Wed, 25 Jan 2023 02:10:59 -0600 Received: from localhost (ileaxei01-snat2.itg.ti.com [10.180.69.6]) by lelv0327.itg.ti.com (8.15.2/8.15.2) with ESMTP id 30P8AvTW033327; Wed, 25 Jan 2023 02:10:58 -0600 From: Dhruva Gole To: Mark Brown CC: , , Vignesh Raghavendra , Vaishnav Achath , Dhruva Gole , , , , Pratyush Yadav Subject: [PATCH v2 2/4] spi: cadence-quadspi: Add flag for direct mode writes Date: Wed, 25 Jan 2023 13:40:21 +0530 Message-ID: <20230125081023.1573712-3-d-gole@ti.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230125081023.1573712-1-d-gole@ti.com> References: <20230125081023.1573712-1-d-gole@ti.com> MIME-Version: 1.0 X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org Create new flag inorder to avoid playing with use_direct_mode flag currently being used throughout the driver. Disable DAC write if auto polling is disabled or CQSPI_DISABLE_DAC_MODE is set. Signed-off-by: Dhruva Gole --- drivers/spi/spi-cadence-quadspi.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) -- 2.25.1 diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c index 6030da942c6e..4bbf6e3ad34a 100644 --- a/drivers/spi/spi-cadence-quadspi.c +++ b/drivers/spi/spi-cadence-quadspi.c @@ -84,6 +84,7 @@ struct cqspi_st { u32 trigger_address; u32 wr_delay; bool use_direct_mode; + bool use_direct_mode_wr; struct cqspi_flash_pdata f_pdata[CQSPI_MAX_CHIPSELECT]; bool use_dma_read; u32 pd_dev_id; @@ -945,6 +946,12 @@ static int cqspi_write_setup(struct cqspi_flash_pdata *f_pdata, reg = readl(reg_base + CQSPI_REG_WR_COMPLETION_CTRL); reg |= CQSPI_REG_WR_DISABLE_AUTO_POLL; writel(reg, reg_base + CQSPI_REG_WR_COMPLETION_CTRL); + /* + * DAC mode require auto polling as flash needs to be polled + * for write completion in case of bubble in SPI transaction + * due to slow CPU/DMA master. + */ + cqspi->use_direct_mode_wr = false; } reg = readl(reg_base + CQSPI_REG_SIZE); @@ -1230,7 +1237,7 @@ static ssize_t cqspi_write(struct cqspi_flash_pdata *f_pdata, * data. */ if (!op->cmd.dtr && cqspi->use_direct_mode && - ((to + len) <= cqspi->ahb_size)) { + cqspi->use_direct_mode_wr && ((to + len) <= cqspi->ahb_size)) { memcpy_toio(cqspi->ahb_base + to, buf, len); return cqspi_wait_idle(cqspi); } @@ -1700,8 +1707,10 @@ static int cqspi_probe(struct platform_device *pdev) cqspi->master_ref_clk_hz); if (ddata->hwcaps_mask & CQSPI_SUPPORTS_OCTAL) master->mode_bits |= SPI_RX_OCTAL | SPI_TX_OCTAL; - if (!(ddata->quirks & CQSPI_DISABLE_DAC_MODE)) + if (!(ddata->quirks & CQSPI_DISABLE_DAC_MODE)) { cqspi->use_direct_mode = true; + cqspi->use_direct_mode_wr = true; + } if (ddata->quirks & CQSPI_SUPPORT_EXTERNAL_DMA) cqspi->use_dma_read = true; if (ddata->quirks & CQSPI_NO_SUPPORT_WR_COMPLETION) From patchwork Wed Jan 25 08:10:22 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dhruva Gole X-Patchwork-Id: 13115089 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 E3041C54E94 for ; Wed, 25 Jan 2023 08:11:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234961AbjAYILX (ORCPT ); Wed, 25 Jan 2023 03:11:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50382 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233330AbjAYILQ (ORCPT ); Wed, 25 Jan 2023 03:11:16 -0500 Received: from fllv0016.ext.ti.com (fllv0016.ext.ti.com [198.47.19.142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A0A6F4709D; Wed, 25 Jan 2023 00:11:13 -0800 (PST) Received: from lelv0265.itg.ti.com ([10.180.67.224]) by fllv0016.ext.ti.com (8.15.2/8.15.2) with ESMTP id 30P8B4vn059195; Wed, 25 Jan 2023 02:11:04 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1674634264; bh=H6KisuMO1+dkW1oxul0NcexVOnMzVPplM1t3KZiQg1k=; h=From:To:CC:Subject:Date:In-Reply-To:References; b=kOFvGhQcoiLPwPe7UJSzl0nr8TqRqydgJB/MPGsi9jteq/L4Wc0GpUnGoBI+XQ/l9 vhI3wub9h+aksqOoUbO+uT+BCGQFXvlHAcXGs5hq8mrRZrIoxynmt5u6c9mu9bcX7I 7vkG7DIUOyp7eSrVFA4fz1E8TjExPh6vR0tNI6T0= Received: from DLEE111.ent.ti.com (dlee111.ent.ti.com [157.170.170.22]) by lelv0265.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 30P8B4Op027318 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 25 Jan 2023 02:11:04 -0600 Received: from DLEE101.ent.ti.com (157.170.170.31) by DLEE111.ent.ti.com (157.170.170.22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.16; Wed, 25 Jan 2023 02:11:04 -0600 Received: from fllv0039.itg.ti.com (10.64.41.19) by DLEE101.ent.ti.com (157.170.170.31) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.16 via Frontend Transport; Wed, 25 Jan 2023 02:11:04 -0600 Received: from localhost (ileaxei01-snat2.itg.ti.com [10.180.69.6]) by fllv0039.itg.ti.com (8.15.2/8.15.2) with ESMTP id 30P8B2mg075654; Wed, 25 Jan 2023 02:11:03 -0600 From: Dhruva Gole To: Mark Brown CC: , , Vignesh Raghavendra , Vaishnav Achath , Dhruva Gole , , , , Pratyush Yadav Subject: [PATCH v2 3/4] spi: cadence-quadspi: setup ADDR Bits in cmd reads Date: Wed, 25 Jan 2023 13:40:22 +0530 Message-ID: <20230125081023.1573712-4-d-gole@ti.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230125081023.1573712-1-d-gole@ti.com> References: <20230125081023.1573712-1-d-gole@ti.com> MIME-Version: 1.0 X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org Setup the Addr bit field while issuing register reads in STIG mode. This is needed for example flashes like cypress define in their transaction table that to read any register there is 1 cmd byte and a few more address bytes trailing the cmd byte. Absence of addr bytes will obviously fail to read correct data from flash register that maybe requested by flash driver because the controller doesn't even specify which address of the flash register the read is being requested from. Signed-off-by: Dhruva Gole --- drivers/spi/spi-cadence-quadspi.c | 11 +++++++++++ 1 file changed, 11 insertions(+) -- 2.25.1 diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c index 4bbf6e3ad34a..a6d0f1b0bb49 100644 --- a/drivers/spi/spi-cadence-quadspi.c +++ b/drivers/spi/spi-cadence-quadspi.c @@ -532,6 +532,17 @@ static int cqspi_command_read(struct cqspi_flash_pdata *f_pdata, /* 0 means 1 byte. */ reg |= (((n_rx - 1) & CQSPI_REG_CMDCTRL_RD_BYTES_MASK) << CQSPI_REG_CMDCTRL_RD_BYTES_LSB); + + /* setup ADDR BIT field */ + if (op->addr.nbytes) { + reg |= (0x1 << CQSPI_REG_CMDCTRL_ADDR_EN_LSB); + reg |= ((op->addr.nbytes - 1) & + CQSPI_REG_CMDCTRL_ADD_BYTES_MASK) + << CQSPI_REG_CMDCTRL_ADD_BYTES_LSB; + + writel(op->addr.val, reg_base + CQSPI_REG_CMDADDRESS); + } + status = cqspi_exec_flash_cmd(cqspi, reg); if (status) return status; From patchwork Wed Jan 25 08:10:23 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dhruva Gole X-Patchwork-Id: 13115090 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 9BE5DC27C76 for ; Wed, 25 Jan 2023 08:11:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235001AbjAYILY (ORCPT ); Wed, 25 Jan 2023 03:11:24 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50720 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234754AbjAYILW (ORCPT ); Wed, 25 Jan 2023 03:11:22 -0500 Received: from lelv0143.ext.ti.com (lelv0143.ext.ti.com [198.47.23.248]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0B1384DE15; Wed, 25 Jan 2023 00:11:17 -0800 (PST) Received: from fllv0035.itg.ti.com ([10.64.41.0]) by lelv0143.ext.ti.com (8.15.2/8.15.2) with ESMTP id 30P8BA9l011886; Wed, 25 Jan 2023 02:11:10 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1674634270; bh=Hn4D1RStKcp308sq3cbg4/Y6SSqzZ28U4qiM8PCYDgk=; h=From:To:CC:Subject:Date:In-Reply-To:References; b=AoHM/UWRS/effmMZCsJiCPgtXBNrhgKYttnXZS4eNB6SIvMs/uMdcR1v62isnjPdc Hd+YwrNpLDwZHGQhCYsfemD0HHuq7n+A+/IRlcjAsxjbSlTlv00iMJ4pvddukd+q0j VxOX8hxIkUORtMxQTL21rD8Cuse1CTOiGPi6ma+w= Received: from DFLE109.ent.ti.com (dfle109.ent.ti.com [10.64.6.30]) by fllv0035.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 30P8BAFU121583 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 25 Jan 2023 02:11:10 -0600 Received: from DFLE103.ent.ti.com (10.64.6.24) by DFLE109.ent.ti.com (10.64.6.30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.16; Wed, 25 Jan 2023 02:11:09 -0600 Received: from lelv0326.itg.ti.com (10.180.67.84) by DFLE103.ent.ti.com (10.64.6.24) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.16 via Frontend Transport; Wed, 25 Jan 2023 02:11:09 -0600 Received: from localhost (ileaxei01-snat2.itg.ti.com [10.180.69.6]) by lelv0326.itg.ti.com (8.15.2/8.15.2) with ESMTP id 30P8B8gG009447; Wed, 25 Jan 2023 02:11:09 -0600 From: Dhruva Gole To: Mark Brown CC: , , Vignesh Raghavendra , Vaishnav Achath , Dhruva Gole , , , , Pratyush Yadav Subject: [PATCH v2 4/4] spi: cadence-quadspi: use STIG mode for small reads Date: Wed, 25 Jan 2023 13:40:23 +0530 Message-ID: <20230125081023.1573712-5-d-gole@ti.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230125081023.1573712-1-d-gole@ti.com> References: <20230125081023.1573712-1-d-gole@ti.com> MIME-Version: 1.0 X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org Fix the issue where some flash chips like cypress S25HS256T return the value of the same register over and over in DAC mode. For example in the TI K3-AM62x Processors refer [0] Technical Reference Manual there is a layer of digital logic in front of the QSPI/OSPI Drive when used in DAC mode. This is part of the Flash Subsystem (FSS) which provides access to external Flash devices. The FSS0_0_SYSCONFIG Register (Offset = 4h) has a BIT Field for OSPI_32B_DISABLE_MODE which has a Reset value = 0. This means, OSPI 32bit mode enabled by default. Thus, by default controller operates in 32 bit mode causing it to always align all data to 4 bytes from a 4byte aligned address. In some flash chips like cypress for example if we try to read some regs in DAC mode then it keeps sending the value of the first register that was requested and inorder to read the next reg, we have to stop and re-initiate a new transaction. This causes wrong register values to be read than what is desired when registers are read in DAC mode. Hence if the data.nbytes is very less then prefer STIG mode for such small reads. [0] https://www.ti.com/lit/ug/spruiv7a/spruiv7a.pdf Signed-off-by: Dhruva Gole Signed-off-by: Dhruva Gole --- drivers/spi/spi-cadence-quadspi.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) -- 2.25.1 diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c index a6d0f1b0bb49..2954c06a7f57 100644 --- a/drivers/spi/spi-cadence-quadspi.c +++ b/drivers/spi/spi-cadence-quadspi.c @@ -1359,7 +1359,13 @@ static int cqspi_mem_process(struct spi_mem *mem, const struct spi_mem_op *op) cqspi_configure(f_pdata, mem->spi->max_speed_hz); if (op->data.dir == SPI_MEM_DATA_IN && op->data.buf.in) { - if (!op->addr.nbytes) + /* + * Performing reads in DAC mode forces to read minimum 4 bytes + * which is unsupported on some flash devices during register + * reads, prefer STIG mode for such small reads. + */ + if (!op->addr.nbytes || + op->data.nbytes <= CQSPI_STIG_DATA_LEN_MAX) return cqspi_command_read(f_pdata, op); return cqspi_read(f_pdata, op);