Re: [PATCH v8 2/2] phy: qcom-mipi-csi2: Add a CSI2 MIPI DPHY driver

[Nihal Kumar Gupta <nihal.gupta@oss.qualcomm.com>]

On 04-06-2026 03:44, Dmitry Baryshkov wrote:
> On Wed, Jun 03, 2026 at 02:37:48PM -0700, Vijay Kumar Tumati wrote:
>>
>>
>> On 6/3/2026 5:57 AM, Bryan O'Donoghue wrote:
>>> On 03/06/2026 13:40, Dmitry Baryshkov wrote:
>>>>> Are you sure about that ?
>>>> Yes.
>>>>
>>>>> ipcat I thought designated lane 7 specifically as clk-lane i.e. named it
>>>>> CLK_LN of some description.
>>>> Split configurations explicitly use other lanes for clocks. E.g. check
>>>> the RB5 Navigation schematics, CAM0B connector.
>>>
>>> Can you please check:
>>>
>>> CSI_3PHASE_COMMON.CSI_COMMON_CTRL5
>>>
>>> 0 LN0_PWRDN_B Lane 0
>>> ...
>>> 7 LNCK_PWRDN_B Clock Lane
>>>
>>> ... just a badly name field
>>>
>>> CSI_2PHASE_CTRL10
>>>
>>> Bit[2] = IS_CLKLANE
>>>
>>> Right so CSI_2PHASE_CTRL10 controls lane mode, indeed. Thanks for checking.
>> I can check this with the HW team. Although the SWI has this knob, there may
>> be some limitations to use any lane as the clk lane. AFAIK, only two
>> specific lanes are clk capable in DPHY mode.>
> 
> Having clock-names property doesn't mean that all values are valid.
> 
CSI_COMMON_CTRL5 is a physical lane power-up bitmap:
- Bits [0,2,4,6] → D-PHY data lanes(LN0, LN2, LN4, LN6)
- Bits [1,3,5] → C-PHY trio lanes(LN1, LN3, LN5)
- Bit [7] → D-PHY clock lane(LNCK) dedicated clock enable

In combo mode, only LN6 can be configurable as a clock lane.

The lane-enable computation in phy_qcom_mipi_csi2_lanes_enable() uses
BIT(data[i].pos) directly, assuming physical bit positions <0 2 4 6>,
but the DT [1] uses conventional indices <0 1 2 3>, producing 0x8F
instead of the correct 0xD5.

This goes unnoticed because the wrong value is immediately overwritten by the 
hardcoded 0xD5 in lane_regs_x1e80100, making the dynamic computation effectively dead.

Could you please fix the driver to map logical lane indices, consistent with the gen2 camss convention.

[1] https://lore.kernel.org/all/20260326-x1e-camss-csi2-phy-dtsi-v3-5-1d5a9306116a@linaro.org

Regards,
Nihal