Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
CC:     Akinobu Mita <akinobu.mita@gmail.com>,
        Mark Brown <broonie@kernel.org>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.4 032/115] spi: omap2-mcspi: poll
 OMAP2_MCSPI_CHSTAT_RXS for PIO transfer
Thread-Topic: [PATCH AUTOSEL for 4.4 032/115] spi: omap2-mcspi: poll
 OMAP2_MCSPI_CHSTAT_RXS for PIO transfer
Thread-Index: AQHTsz9S6raZnGZhsEeNuo2TkYJq4g==
Date:   Sat, 3 Mar 2018 22:31:07 +0000
Message-ID: <20180303223010.27106-32-alexander.levin@microsoft.com>
References: <20180303223010.27106-1-alexander.levin@microsoft.com>
In-Reply-To: <20180303223010.27106-1-alexander.levin@microsoft.com>
Accept-Language: en-US
Content-Language: en-US
received-spf: None (protection.outlook.com: microsoft.com does not designate
 permitted sender hosts)
spamdiagnosticoutput: 1:99
spamdiagnosticmetadata: NSPM
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-Network-Message-Id: 0afe043e-a81a-4cab-7941-08d581578411
X-MS-Exchange-CrossTenant-originalarrivaltime: 03 Mar 2018 22:31:07.4790
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW2PR2101MB1067
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

From: Akinobu Mita <akinobu.mita@gmail.com>

[ Upstream commit 812613591cb652344186c4cd912304ed02138566 ]

When running the spi-loopback-test with slower clock rate like 10 KHz,
the test for 251 bytes transfer was failed.  This failure triggered an
spi-omap2-mcspi's error message "DMA RX last word empty".

This message means that PIO for reading the remaining bytes due to the
DMA transfer length reduction is failed.  This problem can be fixed by
polling OMAP2_MCSPI_CHSTAT_RXS bit in channel status register to wait
until the receive buffer register is filled.

Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 drivers/spi/spi-omap2-mcspi.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index ed8283e7397a..83b53cd956aa 100644
--- a/drivers/spi/spi-omap2-mcspi.c
+++ b/drivers/spi/spi-omap2-mcspi.c
@@ -457,6 +457,8 @@ omap2_mcspi_rx_dma(struct spi_device *spi, struct spi_t=
ransfer *xfer,
 	int			elements =3D 0;
 	int			word_len, element_count;
 	struct omap2_mcspi_cs	*cs =3D spi->controller_state;
+	void __iomem		*chstat_reg =3D cs->base + OMAP2_MCSPI_CHSTAT0;
+
 	mcspi =3D spi_master_get_devdata(spi->master);
 	mcspi_dma =3D &mcspi->dma_channels[spi->chip_select];
 	count =3D xfer->len;
@@ -517,8 +519,8 @@ omap2_mcspi_rx_dma(struct spi_device *spi, struct spi_t=
ransfer *xfer,
 	if (l & OMAP2_MCSPI_CHCONF_TURBO) {
 		elements--;
=20
-		if (likely(mcspi_read_cs_reg(spi, OMAP2_MCSPI_CHSTAT0)
-				   & OMAP2_MCSPI_CHSTAT_RXS)) {
+		if (!mcspi_wait_for_reg_bit(chstat_reg,
+					    OMAP2_MCSPI_CHSTAT_RXS)) {
 			u32 w;
=20
 			w =3D mcspi_read_cs_reg(spi, OMAP2_MCSPI_RX0);
@@ -536,8 +538,7 @@ omap2_mcspi_rx_dma(struct spi_device *spi, struct spi_t=
ransfer *xfer,
 			return count;
 		}
 	}
-	if (likely(mcspi_read_cs_reg(spi, OMAP2_MCSPI_CHSTAT0)
-				& OMAP2_MCSPI_CHSTAT_RXS)) {
+	if (!mcspi_wait_for_reg_bit(chstat_reg, OMAP2_MCSPI_CHSTAT_RXS)) {
 		u32 w;
=20
 		w =3D mcspi_read_cs_reg(spi, OMAP2_MCSPI_RX0);
--=20
2.14.1