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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Serge Semin <Sergey.Semin@baikalelectronics.ru>,
        Georgy Vlasov <Georgy.Vlasov@baikalelectronics.ru>,
        Ramil Zaripov <Ramil.Zaripov@baikalelectronics.ru>,
        Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Arnd Bergmann <arnd@arndb.de>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Feng Tang <feng.tang@intel.com>,
        Rob Herring <robh+dt@kernel.org>, linux-mips@vger.kernel.org,
        devicetree@vger.kernel.org, Mark Brown <broonie@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 095/128] spi: dw: Return any value retrieved from the dma_transfer callback
Date:   Fri, 19 Jun 2020 16:33:09 +0200
Message-Id: <20200619141625.159284957@linuxfoundation.org>
In-Reply-To: <20200619141620.148019466@linuxfoundation.org>
References: <20200619141620.148019466@linuxfoundation.org>
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From: Serge Semin <Sergey.Semin@baikalelectronics.ru>

[ Upstream commit f0410bbf7d0fb80149e3b17d11d31f5b5197873e ]

DW APB SSI DMA-part of the driver may need to perform the requested
SPI-transfer synchronously. In that case the dma_transfer() callback
will return 0 as a marker of the SPI transfer being finished so the
SPI core doesn't need to wait and may proceed with the SPI message
trasnfers pumping procedure. This will be needed to fix the problem
when DMA transactions are finished, but there is still data left in
the SPI Tx/Rx FIFOs being sent/received. But for now make dma_transfer
to return 1 as the normal dw_spi_transfer_one() method.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Cc: Georgy Vlasov <Georgy.Vlasov@baikalelectronics.ru>
Cc: Ramil Zaripov <Ramil.Zaripov@baikalelectronics.ru>
Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Feng Tang <feng.tang@intel.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: devicetree@vger.kernel.org
Link: https://lore.kernel.org/r/20200529131205.31838-3-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/spi/spi-dw-mid.c | 2 +-
 drivers/spi/spi-dw.c     | 7 ++-----
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/spi/spi-dw-mid.c b/drivers/spi/spi-dw-mid.c
index fe0ca3848d35..c079ab36275f 100644
--- a/drivers/spi/spi-dw-mid.c
+++ b/drivers/spi/spi-dw-mid.c
@@ -274,7 +274,7 @@ static int mid_spi_dma_transfer(struct dw_spi *dws, struct spi_transfer *xfer)
 		dma_async_issue_pending(dws->txchan);
 	}
 
-	return 0;
+	return 1;
 }
 
 static void mid_spi_dma_stop(struct dw_spi *dws)
diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index c5a2f369941c..91f44e3e1930 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -384,11 +384,8 @@ static int dw_spi_transfer_one(struct spi_master *master,
 
 	spi_enable_chip(dws, 1);
 
-	if (dws->dma_mapped) {
-		ret = dws->dma_ops->dma_transfer(dws, transfer);
-		if (ret < 0)
-			return ret;
-	}
+	if (dws->dma_mapped)
+		return dws->dma_ops->dma_transfer(dws, transfer);
 
 	if (chip->poll_mode)
 		return poll_transfer(dws);
-- 
2.25.1