Re: [PATCH 0/3] opp: Add bw_factor support to adjust bandwidth dynamically

[Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>]

Hi Viresh,

Can you please review this once.

Thanks & Regards,
Krishna Chaitanya.

On 7/17/2025 7:31 PM, Krishna Chaitanya Chundru wrote:
> The existing OPP table in the device tree for PCIe is shared across
> different link configurations such as data rates 8GT/s x2 and 16GT/s x1.
> These configurations often operate at the same frequency, allowing them
> to reuse the same OPP entries. However, 8GT/s and 16 GT/s may have
> different characteristics beyond frequency—such as RPMh votes in QCOM
> case, which cannot be represented accurately when sharing a single OPP.
> 
> To avoid conflicts and duplication in the device tree, we now define only
> one set of OPP entries per table and introduce a new mechanism to adjust
> bandwidth dynamically using a `bw_factor`.
> 
> The `bw_factor` is a multiplier applied to the average and peak bandwidth
> values of an OPP entry. This allows PCIe drivers to modify the effective
> bandwidth at runtime based on the actual link width without needing
> separate OPP entries for each configuration.
> 
> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
> ---
> Krishna Chaitanya Chundru (3):
>        opp: Add bw_factor support to adjust bandwidth dynamically
>        PCI: qcom: Use bw_factor to adjust bandwidth based on link width
>        arm64: dts: qcom: sm8450: Keep only x1 lane PCIe OPP entries
> 
>   arch/arm64/boot/dts/qcom/sm8450.dtsi   | 17 ++--------------
>   drivers/opp/core.c                     | 37 ++++++++++++++++++++++++++++++++--
>   drivers/opp/opp.h                      |  2 ++
>   drivers/pci/controller/dwc/pcie-qcom.c |  8 ++++++--
>   include/linux/pm_opp.h                 |  7 +++++++
>   5 files changed, 52 insertions(+), 19 deletions(-)
> ---
> base-commit: e2291551827fe5d2d3758c435c191d32b6d1350e
> change-id: 20250717-opp_pcie-793160b2b113
> 
> Best regards,