Re: [PATCH 3/9] usb: dwc3: qcom: Add support for selecting UTMI as reference clock

[Konrad Dybcio]

On 8/25/26 12:42 PM, George Moussalem via B4 Relay wrote:
> From: George Moussalem <george.moussalem@xxxxxxxxxxx>
> 
> On many Qualcomm chipsets, the UTMI clock is used as the reference clock
> (ex. IPQ5018, IPQ6018, and IPQ9574 and more). Since moving to the new
> flattened snps-dwc3 model, it is no longer possible to pass the
> reference clock to the dwc3 core driver.
> 
> The clock rate is used by dwc3 core to derive the reference clock period
> and frame length adjusment. This is needed when the reference clock
> deviates from the hardware default (typically 19.2MHz). Above mentioned
> SoCs use different rates and, as such, the core initializes with the
> wrong values which leads to non-functional USB operation.
> 
> Read the "qcom,select-utmi-as-ref-clk" property to determine if the UTMI
> clock should be used as the reference clock. If so, set it as the
> reference clock in the dwc3_probe_data structure.
> The dwc3 core driver will then use this clock to derive the clock rate.
> 
> Signed-off-by: George Moussalem <george.moussalem@xxxxxxxxxxx>
> ---

There's a shorter patch in flight:

https://lore.kernel.org/linux-arm-msm/20260825-ctrl-v1-2-609e2291814d@xxxxxxxxxxxxxxxx/

Konrad