linux-kernel - Re: [PATCH v2 03/10] PCI: dwc: Implement .pre_scale_bus_bw() & .post_scale_bus

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Message-ID: <6zuyux2emotjxouvo36ijojz4xel7x7aozyem55pmd3xvpbgjs@6abrkkzj3bib>
Date: Fri, 25 Apr 2025 21:32:04 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, 
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>, Jingoo Han <jingoohan1@...il.com>, 
	Lorenzo Pieralisi <lpieralisi@...nel.org>, Krzysztof Wilczyński <kw@...ux.com>, 
	Rob Herring <robh@...nel.org>, Johannes Berg <johannes@...solutions.net>, 
	Jeff Johnson <jjohnson@...nel.org>, linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-msm@...r.kernel.org, mhi@...ts.linux.dev, linux-wireless@...r.kernel.org, 
	ath11k@...ts.infradead.org, quic_pyarlaga@...cinc.com, quic_vbadigan@...cinc.com, 
	quic_vpernami@...cinc.com, quic_mrana@...cinc.com, 
	Jeff Johnson <jeff.johnson@....qualcomm.com>
Subject: Re: [PATCH v2 03/10] PCI: dwc: Implement .pre_scale_bus_bw() &
 .post_scale_bus_bw hook

On Thu, Mar 13, 2025 at 05:10:10PM +0530, Krishna Chaitanya Chundru wrote:
> Add support for pre_scale_bus_bw() & post_scale_bus_bw() function op's.
> Add support for DWC glue drivers to register for these ops.
> 
> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
> ---
>  drivers/pci/controller/dwc/pcie-designware-host.c | 21 +++++++++++++++++++++
>  drivers/pci/controller/dwc/pcie-designware.h      |  2 ++
>  2 files changed, 23 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index ffaded8f2df7..4da4df62c3f8 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -697,10 +697,31 @@ void __iomem *dw_pcie_own_conf_map_bus(struct pci_bus *bus, unsigned int devfn,
>  }
>  EXPORT_SYMBOL_GPL(dw_pcie_own_conf_map_bus);
>  
> +static int dw_pcie_pre_scale_bus_bw(struct pci_bus *bus, int target_speed)
> +{
> +	struct dw_pcie_rp *pp = bus->sysdata;
> +	int ret = 0;
> +
> +	if (pp->ops->pre_scale_bus_bw)
> +		ret = pp->ops->pre_scale_bus_bw(pp, target_speed);
> +
> +	return ret;
> +}
> +
> +static void dw_pcie_post_scale_bus_bw(struct pci_bus *bus, int current_speed)
> +{
> +	struct dw_pcie_rp *pp = bus->sysdata;
> +
> +	if (pp->ops->pre_scale_bus_bw)
> +		pp->ops->post_scale_bus_bw(pp, current_speed);
> +}
> +
>  static struct pci_ops dw_pcie_ops = {
>  	.map_bus = dw_pcie_own_conf_map_bus,
>  	.read = pci_generic_config_read,
>  	.write = pci_generic_config_write,
> +	.pre_scale_bus_bw = dw_pcie_pre_scale_bus_bw,
> +	.post_scale_bus_bw = dw_pcie_post_scale_bus_bw,

Please do not add these multi level ops without necessity. Just populate the
callbacks in qcom_pcie_host_init(). DWC has nothing to do with these callbacks.

- Mani

-- 
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