Change in coreboot[master]: soc/mediatek: dsi: fine tune the delta time for EoTp

[Chen-Tsung Hsieh (Code Review)]

Attention is currently required from: Chen-Tsung Hsieh, jitao shi, Shaoming Chen, Jitao Shi.
Chen-Tsung Hsieh has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/51432 )

Change subject: soc/mediatek: dsi: fine tune the delta time for EoTp
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Patch Set 5:

(1 comment)

File src/soc/mediatek/common/dsi.c:

https://review.coreboot.org/c/coreboot/+/51432/comment/e5db6080_5f97371d 
PS2, Line 207: 10
> The effect is the same with MIPI_DSI_MODE_EOT_PACKET, 12 byte also.

For Jacuzzi projects, yes you keep it as 12.

But for Kukui projects (NOT using anx7625, NOT enable MIPI_DSI_MODE_EOT_PACKET), 
Do we really expect to change it from 12 to 10?

According to the report from analogix, enabling EOTP doesn't always increate 2 bytes, sometimes only 1 byte. So we decide NOT to change timing based on MIPI_DSI_MODE_EOT_PACKET.
I thought the proposed fix from analogix is:
    u32 delta = 12;

-	if (mode_flags & MIPI_DSI_MODE_EOT_PACKET)
 -		delta += 2;
 -

On the other hand, I checked the driver in kernel.
You use 18 or 12 for the delta according to MIPI_DSI_MODE_VIDEO_BURST.
Without checking MIPI_DSI_MODE_EOT_PACKET.

https://chromium.googlesource.com/chromiumos/third_party/kernel/+/refs/heads...:
static void mtk_dsi_config_vdo_timing(struct mtk_dsi *dsi)
{
    ...
    if (dsi->mode_flags & MIPI_DSI_MODE_VIDEO_BURST) {
    	if ((vm->hfront_porch + vm->hback_porch) * dsi_tmp_buf_bpp >
    	    data_phy_cycles * dsi->lanes + 18) {
    		...
    	}
    } else {
    	if ((vm->hfront_porch + vm->hback_porch) * dsi_tmp_buf_bpp >
    	    data_phy_cycles * dsi->lanes + 12) {
    		...
    	}
    }
    ...
}