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

Damon Ding
2024-11-27T11:08:10Z

Hi Heiko:

On 2024/11/27 17:29, Heiko Stübner wrote:
> 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.
>

As for the huge block of DP phy support, I will try to use the existing
rk_hdptx_multi_reg_write() to set regs in next version, maybe the way
can make the codes more concise.

>
>> +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
>

It is really a nice way to separate HDMI and DP modes.

>
>
>
>

Best regards,
Damon