Re: [PATCH 3/8] phy: qcom: qmp-usbc: Add DP phy mode support on QCS615

[Xiangxu Yin]

On 12/10/2024 11:09 PM, Dmitry Baryshkov wrote:
> On Thu, Dec 05, 2024 at 08:31:24PM +0200, Dmitry Baryshkov wrote:
>> On Thu, Dec 05, 2024 at 09:26:47PM +0800, Xiangxu Yin wrote:
>>>
>>>
>>> On 11/29/2024 10:33 PM, Dmitry Baryshkov wrote:
>>>> On Fri, 29 Nov 2024 at 09:59, Xiangxu Yin <quic_xiangxuy@xxxxxxxxxxx> wrote:
>>>>>
>>>>> Extended DP support for QCS615 USB or DP phy. Differentiated between
>>>>> USBC and DP PHY using the match table’s type, dynamically generating
>>>>> different types of cfg and layout attributes during initialization based
>>>>> on this type. Static variables are stored in cfg, while parsed values
>>>>> are organized into the layout structure.
>>>>
>>>> We didn't have an understanding / conclusion whether
>>>> qcom,usb-ssphy-qmp-usb3-or-dp PHYs are actually a single device / PHY
>>>> or two PHYs being placed next to each other. Could you please start
>>>> your commit message by explaining it? Or even better, make that a part
>>>> of the cover letter for a new series touching just the USBC PHY
>>>> driver. DP changes don't have anything in common with the PHY changes,
>>>> so you can split the series into two.
>>>>
>>> Before implement DP extension, we have discussed with abhinav and krishna about whether use combo, usbc or separate phy.
>>
>> What is "DP extension"?
>>
I'm sorry confusion casued by my description. It's means extend DP implemnt for USBC phy driver.
>>>
>>> We identified that DP and USB share some common controls for phy_mode and orientation.
>>> Specifically, 'TCSR_USB3_0_DP_PHYMODE' controls who must use the lanes - USB or DP,
>>> while PERIPH_SS_USB0_USB3PHY_PCS_MISC_TYPEC_CTRL controls the orientation.
>>> It would be more efficient for a single driver to manage these controls. 
>>
>> The question is about the hardware, not about the driver.
>>
>>> Additionally, this PHY does not support Alt Mode, and the two control registers are located in separate address spaces. 
>>> Therefore, even though the orientation for DP on this platform is always normal and connected to the video output board, 
>>> we still decided to base it on the USBC extension.
>>
>> Could you please clarify, do usb3-or-dp PHYs support DP-over-USB-C? I
>> thought that usbc-or-dp platforms support that, but they don't
>> support DP+USB pin configuration. Note, the question is broader than
>> just QCS615, it covers the PHY type itself.
>>
>> Also, is TCSR configuration read/write or read-only? Are we supposed to
>> set the register from OS or are we supposed to read it and thus detemine
>> the PHY mode?
> 
> Any updates on these two topics?
> 
Still confirming detail info with HW & design team.
I’ll update the information that has been confirmed so far.
This phy support DP-over-USB-C,but it's not support alt-mode which 2 lane work for DP, other 2 lane work for USB.
TCSR phy mode is read/write reg and we can read for determine phy mode.