Some DSI RX devices (for example, anx7625) require last alignment of packets on all lanes after each row of data is sent. Otherwise, there will be some issues of shift or scroll for screen.
Take horizontal_sync_active_byte for a example, we roundup the HSA packet data to lane number, and the subtraction of 2 is the packet data value added by the roundup operation, making the long packets are integer multiples of lane number. This value (2) varies with the lane number, and that is the reason we do this operation when the lane number is 4.
In the previous operation of function "mtk_dsi_config_vdo_timing", the length of HSA and HFP data packets has been adjusted to an integration multiple of lane number. Since the number of RGB data packets cannot be guaranteed to be an integer multiple of lane number, we modify the data packet length of HBP so that the number of HBP + RGB is equal to the lane number. So after sending a line of data (HSA + HBP + RGB + HFP), the data lanes are aligned.
Signed-off-by: Jitao Shi jitao.shi@mediatek.com Signed-off-by: Rex-BC Chen rex-bc.chen@mediatek.com Signed-off-by: Xinlei Lee xinlei.lee@mediatek.com Reviewed-by: Andrzej Hajda andrzej.hajda@intel.com Reviewed-by: AngeloGioacchino Del Regno angelogioacchino.delregno@collabora.com Acked-by: Chun-Kuang Hu chunkuang.hu@kernel.org --- drivers/gpu/drm/mediatek/mtk_dsi.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c index bced4c7d668e..208463dbf326 100644 --- a/drivers/gpu/drm/mediatek/mtk_dsi.c +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c @@ -500,6 +500,18 @@ static void mtk_dsi_config_vdo_timing(struct mtk_dsi *dsi) DRM_WARN("HFP + HBP less than d-phy, FPS will under 60Hz\n"); }
+ if ((dsi->mode_flags & MIPI_DSI_HS_PKT_END_ALIGNED) && + (dsi->lanes == 4)) { + horizontal_sync_active_byte = + roundup(horizontal_sync_active_byte, dsi->lanes) - 2; + horizontal_frontporch_byte = + roundup(horizontal_frontporch_byte, dsi->lanes) - 2; + horizontal_backporch_byte = + roundup(horizontal_backporch_byte, dsi->lanes) - 2; + horizontal_backporch_byte -= + (vm->hactive * dsi_tmp_buf_bpp + 2) % dsi->lanes; + } + writel(horizontal_sync_active_byte, dsi->regs + DSI_HSA_WC); writel(horizontal_backporch_byte, dsi->regs + DSI_HBP_WC); writel(horizontal_frontporch_byte, dsi->regs + DSI_HFP_WC);