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Tue, 19 Feb 2019 09:01:05 -0800 Received: from linux.ad.analog.com (10.50.1.179) by NWD2HUBCAS7.ad.analog.com (10.64.69.107) with Microsoft SMTP Server id 14.3.408.0; Tue, 19 Feb 2019 12:01:05 -0500 From: Stefan Popa To: CC: , , , , Michael Hennerich Subject: [PATCH] drivers: spi: core: Add optional stall delay between cs_change transfers Date: Tue, 19 Feb 2019 19:00:36 +0200 Message-ID: <1550595636-23598-1-git-send-email-stefan.popa@analog.com> X-Mailer: git-send-email 2.7.4 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)(396003)(39860400002)(376002)(136003)(346002)(2980300002)(189003)(199004)(476003)(486006)(126002)(72206003)(44832011)(426003)(50226002)(336012)(186003)(305945005)(7696005)(7636002)(51416003)(316002)(2616005)(356004)(6666004)(478600001)(8676002)(8936002)(5660300002)(4326008)(36756003)(107886003)(14444005)(50466002)(77096007)(26005)(2906002)(6916009)(47776003)(48376002)(246002)(16586007)(106466001)(54906003)(2351001)(106002);DIR:OUT;SFP:1101;SCL:1;SRVR:CY4PR03MB3062;H:nwd2mta2.analog.com;FPR:;SPF:Pass;LANG:en;PTR:nwd2mail11.analog.com;MX:1;A:1; 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The default value of 10us are not enough. Introduce a per transfer configurable delay. Signed-off-by: Michael Hennerich Signed-off-by: Stefan Popa --- 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 9a7def7..717b92a 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -1144,7 +1144,8 @@ 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_stall_delay_us ? + xfer->cs_change_stall_delay_us : 10); spi_set_cs(msg->spi, true); } } diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 314d922..273774c 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -702,6 +702,8 @@ 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_stall_delay_us: 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 @@ -788,6 +790,7 @@ struct spi_transfer { #define SPI_NBITS_DUAL 0x02 /* 2bits transfer */ #define SPI_NBITS_QUAD 0x04 /* 4bits transfer */ u8 bits_per_word; + u8 cs_change_stall_delay_us; u16 delay_usecs; u32 speed_hz; u16 word_delay;