linux-kernel - [PATCH v4 14/21] spi: dw: Explicitly de-assert CS on SPI transfer completion

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Message-ID: <20201007235511.4935-15-Sergey.Semin@baikalelectronics.ru>
Date:   Thu, 8 Oct 2020 02:55:03 +0300
From:   Serge Semin <Sergey.Semin@...kalelectronics.ru>
To:     Mark Brown <broonie@...nel.org>,
        Serge Semin <fancer.lancer@...il.com>
CC:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Ramil Zaripov <Ramil.Zaripov@...kalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Lars Povlsen <lars.povlsen@...rochip.com>,
        "wuxu . wu" <wuxu.wu@...wei.com>, Feng Tang <feng.tang@...el.com>,
        Rob Herring <robh+dt@...nel.org>, <linux-spi@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v4 14/21] spi: dw: Explicitly de-assert CS on SPI transfer completion

By design of the currently available native set_cs callback, the CS
de-assertion will be done only if it's required by the corresponding
controller capability. But in order to pre-fill the Tx FIFO buffer with
data during the SPI memory ops execution the SER register needs to be left
cleared before that. We'll also need a way to explicitly set and clear the
corresponding CS bit at a certain moment of the operation. Let's alter
the set_cs function then to also de-activate the CS, when it's required.

Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
---
 drivers/spi/spi-dw-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
index ac87ff6d8be4..76e323db170f 100644
--- a/drivers/spi/spi-dw-core.c
+++ b/drivers/spi/spi-dw-core.c
@@ -100,7 +100,7 @@ void dw_spi_set_cs(struct spi_device *spi, bool enable)
 	 */
 	if (cs_high == enable)
 		dw_writel(dws, DW_SPI_SER, BIT(spi->chip_select));
-	else if (dws->caps & DW_SPI_CAP_CS_OVERRIDE)
+	else
 		dw_writel(dws, DW_SPI_SER, 0);
 }
 EXPORT_SYMBOL_GPL(dw_spi_set_cs);
-- 
2.27.0