From ceb001b077af64b20a8027132cfe015c80f4319d Mon Sep 17 00:00:00 2001 From: Timur Tabi Date: Tue, 16 Oct 2012 17:33:49 -0500 Subject: [PATCH] drivers/video: fsl-diu-fb: don't touch registers for unused features We don't use the writeback buffer, so don't initialize the registers for that feature. The default value for SYN_POL is already zero, so don't re-initialize it. Writing the INT_STATUS register does nothing. The value that we write to the PLUT register only makes sense on the MPC8610 and P1022, so don't touch that register on the MPC5121. Signed-off-by: Timur Tabi --- drivers/video/fsl-diu-fb.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/drivers/video/fsl-diu-fb.c b/drivers/video/fsl-diu-fb.c index 37175ac6584a..0883bc42cd5a 100644 --- a/drivers/video/fsl-diu-fb.c +++ b/drivers/video/fsl-diu-fb.c @@ -825,12 +825,8 @@ static void update_lcdc(struct fb_info *info) out_be32(&hw->gamma, DMA_ADDR(data, gamma)); out_be32(&hw->cursor, DMA_ADDR(data, cursor)); - out_be32(&hw->bgnd, 0x007F7F7F); /* BGND */ - out_be32(&hw->bgnd_wb, 0); /* BGND_WB */ - out_be32(&hw->disp_size, (var->yres << 16 | var->xres)); - /* DISP SIZE */ - out_be32(&hw->wb_size, 0); /* WB SIZE */ - out_be32(&hw->wb_mem_addr, 0); /* WB MEM ADDR */ + out_be32(&hw->bgnd, 0x007F7F7F); /* Set background to grey */ + out_be32(&hw->disp_size, (var->yres << 16) | var->xres); /* Horizontal and vertical configuration register */ temp = var->left_margin << 22 | /* BP_H */ @@ -847,9 +843,20 @@ static void update_lcdc(struct fb_info *info) diu_ops.set_pixel_clock(var->pixclock); - out_be32(&hw->syn_pol, 0); /* SYNC SIGNALS POLARITY */ - out_be32(&hw->int_status, 0); /* INTERRUPT STATUS */ +#ifndef CONFIG_PPC_MPC512x + /* + * The PLUT register is defined differently on the MPC5121 than it + * is on other SOCs. Unfortunately, there's no documentation that + * explains how it's supposed to be programmed, so for now, we leave + * it at the default value on the MPC5121. + * + * For other SOCs, program it for the highest priority, which will + * reduce the chance of underrun. Technically, we should scale the + * priority to match the screen resolution, but doing that properly + * requires delicate fine-tuning for each use-case. + */ out_be32(&hw->plut, 0x01F5F666); +#endif /* Enable the DIU */ enable_lcdc(info);