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Wed, 17 Jul 2019 11:51:37 +0000 Received: from NWD2HUBCAS7.ad.analog.com (nwd2hubcas7.ad.analog.com [10.64.69.107]) by nwd2mta2.analog.com (8.13.8/8.13.8) with ESMTP id x6HBpXt0003269 (version=TLSv1/SSLv3 cipher=AES256-SHA bits=256 verify=OK); Wed, 17 Jul 2019 04:51:33 -0700 Received: from saturn.ad.analog.com (10.48.65.145) by NWD2HUBCAS7.ad.analog.com (10.64.69.107) with Microsoft SMTP Server id 14.3.408.0; Wed, 17 Jul 2019 07:51:32 -0400 From: Alexandru Ardelean To: , , , CC: , , , , Alexandru Ardelean , Michael Hennerich Subject: [PATCH 1/4][V2] drivers: spi: core: Add optional delay between cs_change transfers Date: Wed, 17 Jul 2019 14:51:06 +0300 Message-ID: <20190717115109.15168-2-alexandru.ardelean@analog.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190717115109.15168-1-alexandru.ardelean@analog.com> References: <20190717115109.15168-1-alexandru.ardelean@analog.com> MIME-Version: 1.0 X-ADIRoutedOnPrem: True X-EOPAttributedMessage: 0 X-MS-Office365-Filtering-HT: Tenant X-Forefront-Antispam-Report: CIP:137.71.25.57;IPV:NLI;CTRY:US;EFV:NLI;SFV:NSPM;SFS:(10009020)(2980300002)(199004)(189003)(70586007)(2201001)(305945005)(5660300002)(2906002)(11346002)(476003)(2616005)(336012)(446003)(70206006)(246002)(110136005)(126002)(7636002)(54906003)(86362001)(4326008)(486006)(14444005)(106002)(426003)(8676002)(1076003)(48376002)(47776003)(186003)(44832011)(6666004)(356004)(50226002)(50466002)(76176011)(2870700001)(8936002)(7696005)(51416003)(498600001)(26005)(107886003)(36756003);DIR:OUT;SFP:1101;SCL:1;SRVR:MN2PR03MB4720;H:nwd2mta2.analog.com;FPR:;SPF:Pass;LANG:en;PTR:nwd2mail11.analog.com;A:1;MX:1; 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The default value of 10us is not enough. This change makes the delay configurable for when the next CS change goes active. Signed-off-by: Michael Hennerich Signed-off-by: Alexandru Ardelean --- drivers/spi/spi.c | 3 ++- include/linux/spi/spi.h | 3 +++ 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 5e75944ad5d1..02fd00bcaace 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -1163,7 +1163,8 @@ static int spi_transfer_one_message(struct spi_controller *ctlr, keep_cs = true; } else { spi_set_cs(msg->spi, false); - udelay(10); + udelay(xfer->cs_change_delay_usecs ? + xfer->cs_change_delay_usecs : 10); spi_set_cs(msg->spi, true); } } diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 053abd22ad31..c884b3b94841 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -734,6 +734,8 @@ extern void spi_res_release(struct spi_controller *ctlr, * transfer. If 0 the default (from @spi_device) is used. * @bits_per_word: select a bits_per_word other than the device default * for this transfer. If 0 the default (from @spi_device) is used. + * @cs_change_delay_usecs: microseconds to delay between cs_change + * transfers. * @cs_change: affects chipselect after this transfer completes * @delay_usecs: microseconds to delay after this transfer before * (optionally) changing the chipselect status, then starting @@ -823,6 +825,7 @@ struct spi_transfer { #define SPI_NBITS_QUAD 0x04 /* 4bits transfer */ u8 bits_per_word; u8 word_delay_usecs; + u8 cs_change_delay_usecs; u16 delay_usecs; u32 speed_hz; u16 word_delay;