[PATCH] drm/sun4i: Fix dsi dcs long write function

From: Ondrej Jirman <megous@megous.com>
To: linux-sunxi@googlegroups.com
Cc: Ondrej Jirman <megous@megous.com>,
	David Airlie <airlied@linux.ie>,
	open list <linux-kernel@vger.kernel.org>,
	"open list:DRM DRIVERS FOR ALLWINNER A10"
	<dri-devel@lists.freedesktop.org>, Chen-Yu Tsai <wens@csie.org>,
	Maxime Ripard <mripard@kernel.org>,
	Daniel Vetter <daniel@ffwll.ch>,
	"moderated list:ARM/Allwinner sunXi SoC support"
	<linux-arm-kernel@lists.infradead.org>
Subject: [PATCH] drm/sun4i: Fix dsi dcs long write function
Date: Fri, 28 Aug 2020 13:24:44 +0200	[thread overview]
Message-ID: <20200828112444.916455-1-megous@megous.com> (raw)

It's writing too much data. regmap_bulk_write expects number of
register sized chunks to write, not a byte sized length of the
bounce buffer. Bounce buffer needs to be padded too, so that
regmap_bulk_write will not read past the end of the buffer.

Signed-off-by: Ondrej Jirman <megous@megous.com>
---
 drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
index 7f13f4d715bf..840fad1b68dd 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
@@ -889,7 +889,7 @@ static int sun6i_dsi_dcs_write_long(struct sun6i_dsi *dsi,
 	regmap_write(dsi->regs, SUN6I_DSI_CMD_TX_REG(0),
 		     sun6i_dsi_dcs_build_pkt_hdr(dsi, msg));
 
-	bounce = kzalloc(msg->tx_len + sizeof(crc), GFP_KERNEL);
+	bounce = kzalloc(msg->tx_len + sizeof(crc) + 3, GFP_KERNEL);
 	if (!bounce)
 		return -ENOMEM;
 
@@ -900,7 +900,7 @@ static int sun6i_dsi_dcs_write_long(struct sun6i_dsi *dsi,
 	memcpy((u8 *)bounce + msg->tx_len, &crc, sizeof(crc));
 	len += sizeof(crc);
 
-	regmap_bulk_write(dsi->regs, SUN6I_DSI_CMD_TX_REG(1), bounce, len);
+	regmap_bulk_write(dsi->regs, SUN6I_DSI_CMD_TX_REG(1), bounce, DIV_ROUND_UP(len, 4));
 	regmap_write(dsi->regs, SUN6I_DSI_CMD_CTL_REG, len + 4 - 1);
 	kfree(bounce);
 
-- 
2.28.0


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