drm/sun4i: Fix dsi dcs long write function

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.

Fixes: 133add5b5ad4 ("drm/sun4i: Add Allwinner A31 MIPI-DSI controller support")
Signed-off-by: Ondrej Jirman <megous@megous.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Reviewed-by: Jernej Skrabec <jernej.skrabec@siol.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20200828125032.937148-1-megous@megous.com

diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
index aa67cb0..32d4c3f 100644 (file)
--- 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(ALIGN(msg->tx_len + sizeof(crc), 4), 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);