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: 13115083 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 45A8EC54E94 for ; Wed, 25 Jan 2023 08:13:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:CC:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=9nxznp5KxE8jXQH126boYdg8+TB6Ik98pNm30FNW5Yw=; b=b41t9DwVieqy3z UrxUhMwJsEzqkyHeNyd584iJExs0BjIlmrjGOiEezzoFTMichsC6B3HjlRKT892FCtw1jKRrM8Sjj u4Q7nDvj3qTcSvP4YPjOnKZpoptsbvCrs3agLrF2c1MwhrYsFOENPVK6EYECl1X2Tjs7r2g8d8Vvd vvUXTdhha8XGWB6MVUjaj0d4tFyIz89ddMPB1fTCl3cm2slrYg5DyIBcz/+kv1m5kktyOwBRHBTJo 8eFUtPD6M7GI6jf+aLIP5CJt2vI3zG6P6uu7+poCe6H14QYNdb97dryp7ZtNql8Fz16/mZFee1MaM Vc32kGgOE0ZnD04H89Sw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pKasz-006L10-Nz; Wed, 25 Jan 2023 08:12:02 +0000 Received: from lelv0143.ext.ti.com ([198.47.23.248]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1pKasF-006KjT-Li; Wed, 25 Jan 2023 08:11:17 +0000 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230125_001115_816529_E46B058E X-CRM114-Status: GOOD ( 18.14 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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);