linux-kernel - Re: [PATCH v4 1/3] PCI: endpoint: Add helper function pci_epf_get_bar_required

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Message-ID: <aOOdaDdxCAkmGbkd@ryzen>
Date: Mon, 6 Oct 2025 12:43:52 +0200
From: Niklas Cassel <cassel@...nel.org>
To: Frank Li <Frank.Li@....com>
Cc: Manivannan Sadhasivam <mani@...nel.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>, Jon Mason <jdmason@...zu.us>,
	Dave Jiang <dave.jiang@...el.com>, Allen Hubbe <allenbh@...il.com>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	ntb@...ts.linux.dev, imx@...ts.linux.dev
Subject: Re: [PATCH v4 1/3] PCI: endpoint: Add helper function
 pci_epf_get_bar_required_size()

On Tue, Sep 30, 2025 at 04:39:37PM -0400, Frank Li wrote:
> Introduce pci_epf_get_bar_required_size() to retrieve the required BAR
> size and memory size. Prepare for adding support to set an MMIO address to
> a specific BAR.
> 
> Use two variables 'aligned_bar_size' and 'aligned_mem_size' to avoid
> confuse.

'aligned_bar_size' has been renamed, so this sentence should be updated.


(snip)

> @@ -308,7 +327,9 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar,
>  	}
>  
>  	dev = epc->dev.parent;
> -	space = dma_alloc_coherent(dev, aligned_size, &phys_addr, GFP_KERNEL);
> +
> +	space = dma_alloc_coherent(dev, aligned_mem_size,
> +				   &phys_addr, GFP_KERNEL);
>  	if (!space) {
>  		dev_err(dev, "failed to allocate mem space\n");
>  		return NULL;
> @@ -317,7 +338,7 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar,
>  	epf_bar[bar].phys_addr = phys_addr;
>  	epf_bar[bar].addr = space;
>  	epf_bar[bar].size = size;
> -	epf_bar[bar].aligned_size = aligned_size;
> +	epf_bar[bar].aligned_size = aligned_mem_size;

I like that this local variable is now named aligned_mem_size
to more clearly highlight that it is the aligned _memory_ size.

Perhaps you could also rename the struct pci_epf_bar struct member
'aligned_size' to 'aligned_mem_size' or perhaps even better,
'backing_mem_size' or 'mem_size' ?


Kind regards,
Niklas