[M] Change in coreboot[main]: soc/mediatek/common/dp: Add read/write APIs for DP Phy register

[Yu-Ping Wu (Code Review)]

Attention is currently required from: Hung-Te Lin, Yidi Lin.

Yu-Ping Wu has posted comments on this change by Yidi Lin. ( https://review.coreboot.org/c/coreboot/+/85914?usp=email )

Change subject: soc/mediatek/common/dp: Add read/write APIs for DP Phy register
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Patch Set 1:

(1 comment)

File src/soc/mediatek/common/dp/dptx_hal_common.c:

https://review.coreboot.org/c/coreboot/+/85914/comment/f9ce26d2_ef221b85?usp... :
PS1, Line 120: /*
             : 	 * TODO: modify to clrsetbits32(addr, mask, val);
             : 	 * There is asserion error when testing assert((val & mask) == val).
             : 	 */
> Since this is newly added code, could you find where the bug is? We may add `assert(val & mask == va […]

I checked all the `mtk_dp_phy_mask` callers, and think the assertion is always valid. `swing_val` and `pre_emphasis` are both 2-bit values, and the masks are set correctly.