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From:   Philippe Cornu <philippe.cornu@st.com>
To:     Archit Taneja <architt@codeaurora.org>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        David Airlie <airlied@linux.ie>,
        Philippe Cornu <philippe.cornu@st.com>,
        Brian Norris <briannorris@chromium.org>,
        Benjamin Gaignard <benjamin.gaignard@linaro.org>,
        Bhumika Goyal <bhumirks@gmail.com>,
        <dri-devel@lists.freedesktop.org>, <linux-kernel@vger.kernel.org>,
        "Sandy Huang" <hjc@rock-chips.com>,
        Heiko Stubner <heiko@sntech.de>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-rockchip@lists.infradead.org>
CC:     Yannick Fertre <yannick.fertre@st.com>,
        Vincent Abriou <vincent.abriou@st.com>,
        Alexandre Torgue <alexandre.torgue@st.com>,
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        Ludovic Barre <ludovic.barre@st.com>,
        Mickael Reulier <mickael.reulier@st.com>
Subject: [PATCH v2 1/2] drm/bridge/synopsys: dsi: Add a warning msg on dsi read requests
Date:   Thu, 25 Jan 2018 11:37:59 +0100
Message-ID: <20180125103800.1999-2-philippe.cornu@st.com>
In-Reply-To: <20180125103800.1999-1-philippe.cornu@st.com>
References: <20180125103800.1999-1-philippe.cornu@st.com>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The dcs/generic dsi read feature is not yet implemented so it
is important to warn the host_transfer() caller in case of
read operation requests.

Signed-off-by: Philippe Cornu <philippe.cornu@st.com>
---
 drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
index daec7881be6d..72ecaeb40822 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
@@ -405,6 +405,12 @@ static ssize_t dw_mipi_dsi_host_transfer(struct mipi_dsi_host *host,
 	struct mipi_dsi_packet packet;
 	int ret;
 
+	if (msg->rx_buf || msg->rx_len) {
+		/* TODO dw drv improvements: implement read feature */
+		dev_warn(dsi->dev, "read operations not yet implemented\n");
+		return -EINVAL;
+	}
+
 	ret = mipi_dsi_create_packet(&packet, msg);
 	if (ret) {
 		dev_err(dsi->dev, "failed to create packet: %d\n", ret);
-- 
2.15.1