From fd2cb71bbc383edbfe73ce3770569c7259cfb939 Mon Sep 17 00:00:00 2001 From: Brian Norris Date: Tue, 9 Jan 2018 12:32:48 -0800 Subject: [PATCH] drm/bridge/synopsys: dsi: handle endianness correctly in dw_mipi_dsi_write() We're filling the "remainder" word with little-endian data, then writing it out to IO registers with endian-correcting writel(). That probably won't work on big-endian systems. Let's mark the "remainder" variable as LE32 (since we fill it with memcpy()) and do the swapping explicitly. Some of this function could be done more easily without memcpy(), but the unaligned "remainder" case is a little hard to do without potentially overrunning 'tx_buf', so I just applied the same solution in all cases (memcpy() + le32_to_cpu()). Tested only on a little-endian system. Signed-off-by: Brian Norris Reviewed-by: Andrzej Hajda Signed-off-by: Archit Taneja Link: https://patchwork.freedesktop.org/patch/msgid/20180109203248.139249-2-briannorris@chromium.org --- drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c index 8d90079707ea..c83049d66baf 100644 --- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c +++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c @@ -360,18 +360,18 @@ static int dw_mipi_dsi_write(struct dw_mipi_dsi *dsi, { const u8 *tx_buf = packet->payload; int len = packet->payload_length, pld_data_bytes = sizeof(u32), ret; - u32 remainder; + __le32 word; u32 val; while (len) { if (len < pld_data_bytes) { - remainder = 0; - memcpy(&remainder, tx_buf, len); - dsi_write(dsi, DSI_GEN_PLD_DATA, remainder); + word = 0; + memcpy(&word, tx_buf, len); + dsi_write(dsi, DSI_GEN_PLD_DATA, le32_to_cpu(word)); len = 0; } else { - memcpy(&remainder, tx_buf, pld_data_bytes); - dsi_write(dsi, DSI_GEN_PLD_DATA, remainder); + memcpy(&word, tx_buf, pld_data_bytes); + dsi_write(dsi, DSI_GEN_PLD_DATA, le32_to_cpu(word)); tx_buf += pld_data_bytes; len -= pld_data_bytes; } @@ -386,9 +386,9 @@ static int dw_mipi_dsi_write(struct dw_mipi_dsi *dsi, } } - remainder = 0; - memcpy(&remainder, packet->header, sizeof(packet->header)); - return dw_mipi_dsi_gen_pkt_hdr_write(dsi, remainder); + word = 0; + memcpy(&word, packet->header, sizeof(packet->header)); + return dw_mipi_dsi_gen_pkt_hdr_write(dsi, le32_to_cpu(word)); } static ssize_t dw_mipi_dsi_host_transfer(struct mipi_dsi_host *host, -- 2.30.2