Re: [PATCH v1 04/10] phy: phy-rockchip-samsung-hdptx: Add support for eDP mode

Heiko Stübner
2024-11-27T09:29:15Z

Hi Damon,

Am Mittwoch, 27. November 2024, 08:51:51 CET schrieb Damon Ding:
> Add basic support for RBR/HBR/HBR2 link rates, and the voltage swing and
> pre-emphasis configurations of each link rate have been verified according
> to the eDP 1.3 requirements.
>
> Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
> ---

[ ... huge block of DP phy support ...]

yes that block was huge, but I also don't see a way to split that up in a
useful way, so it should be fine.

> +static int rk_hdptx_phy_set_mode(struct phy *phy, enum phy_mode mode,
> + int submode)
> +{
> + return 0;
> +}

I think it might make sense to go the same way as the DCPHY and also
naneng combophy, to use #phy-cells = 1 to select the phy-mode via DT .

See [0] for Sebastians initial suggestion regarding the DC-PHY.
The naneng combophy already uses that scheme of mode-selection too.

There is of course the issue of backwards-compatibility, but that can be
worked around in the binding with something like:

'#phy-cells':
enum: [0, 1]
description: |
If #phy-cells is 0, PHY mode is set to PHY_TYPE_HDMI
If #phy-cells is 1 mode is set in the PHY cells. Supported modes are:
- PHY_TYPE_HDMI
- PHY_TYPE_DP
See include/dt-bindings/phy/phy.h for constants.

PHY_TYPE_HDMI needs to be added to include/dt-bindings/phy/phy.h
but PHY_TYPE_DP is already there.

That way we would standardize on one form of accessing phy-types
on rk3588 :-) .

Also see the Mediatek CSI rx phy doing this too already [1]

Heiko

[0] https://lore.kernel.org/linux-rockchip/udad4qf3o7kt45nuz6gxsvsmprh4rnyfxfogopmih6ucznizih@7oj2jrnlfonz/
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/phy/mediatek,mt8365-csi-rx.yaml