Piteball/android_kernel_google_msm
1
0
Fork 0
mirror of https://github.com/followmsi/android_kernel_google_msm.git synced 2024-11-06 23:17:41 +00:00
Code Issues Projects Releases Wiki Activity

msm_fb: display: add mdp clk rate calculation for low vbp

Browse source 
For the panels that have low v_back_porch, if h/w FIR scaling is used,
during vbp time, mdp clk should be fast enough to output a line from 4
input lines. MDP rate equation for very small scaling, e.g. 1 or 2
pixels' upscaling or downscaling cannot cover this case, where
underruns are seen on those panels.

Change-Id: I4f35f98c2c1bc4ef04dfee193427bd3ff674945d
Signed-off-by: Huaibin Yang <huaibiny@codeaurora.org>
Signed-off-by: Siddhartha Agrawal <agrawals@codeaurora.org>
This commit is contained in:
Huaibin Yang 2012-08-22 10:36:46 -07:00 committed by Stephen Boyd
parent 5f6cce3acf
commit 5aac7da9b0
1 changed files with 16 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

17
drivers/video/msm/mdp4_overlay.c
View file

@ -2577,6 +2577,22 @@ static int mdp4_calc_pipe_mdp_clk(struct msm_fb_data_type *mfd,
rst >>= shift;
/*
* There is one special case for the panels that have low
* v_back_porch (<=4), mdp clk should be fast enough to buffer
* 4 lines input during back porch time if scaling is
* required(FIR).
*/
if ((mfd->panel_info.lcdc.v_back_porch <= 4) &&
(pipe->src_h != pipe->dst_h)) {
u32 clk = 0;
clk = 4 * (pclk >> shift) / mfd->panel_info.lcdc.v_back_porch;
clk <<= shift;
pr_debug("%s: mdp clk rate %d based on low vbp %d\n",
__func__, clk, mfd->panel_info.lcdc.v_back_porch);
rst = (rst > clk) ? rst : clk;
}
/*
* If the calculated mdp clk is less than panel pixel clk,
* most likely due to upscaling, mdp clk rate will be set to
@ -3676,4 +3692,3 @@ done:
mutex_unlock(&mfd->dma->ov_mutex);
return err;
}