linux-kernel - Re: [PATCH v19 04/10] PCI: endpoint: Add pci_epf_align_inbound

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Message-ID: <n6wdkexskwjd7k5zwaaqeb36zdsxzcshsm7f5czv44rmocswex@pzbpehep2teu>
Date: Wed, 2 Jul 2025 18:01:18 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: Frank Li <Frank.Li@....com>
Cc: Kishon Vijay Abraham I <kishon@...nel.org>, 
	"Rafael J. Wysocki" <rafael@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, 
	Anup Patel <apatel@...tanamicro.com>, Marc Zyngier <maz@...nel.org>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Danilo Krummrich <dakr@...nel.org>, 
	Bjorn Helgaas <bhelgaas@...gle.com>, Arnd Bergmann <arnd@...db.de>, Shuah Khan <shuah@...nel.org>, 
	Richard Zhu <hongxing.zhu@....com>, Lucas Stach <l.stach@...gutronix.de>, 
	Lorenzo Pieralisi <lpieralisi@...nel.org>, Rob Herring <robh@...nel.org>, Shawn Guo <shawnguo@...nel.org>, 
	Sascha Hauer <s.hauer@...gutronix.de>, Pengutronix Kernel Team <kernel@...gutronix.de>, 
	Fabio Estevam <festevam@...il.com>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
	Conor Dooley <conor+dt@...nel.org>, Krzysztof Wilczyński <kwilczynski@...nel.org>, 
	Niklas Cassel <cassel@...nel.org>, dlemoal@...nel.org, jdmason@...zu.us, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, linux-pci@...r.kernel.org, 
	linux-kselftest@...r.kernel.org, imx@...ts.linux.dev, devicetree@...r.kernel.org
Subject: Re: [PATCH v19 04/10] PCI: endpoint: Add
 pci_epf_align_inbound_addr() helper for address alignment

On Mon, Jun 09, 2025 at 12:34:16PM GMT, Frank Li wrote:
> Introduce the helper function pci_epf_align_inbound_addr() to adjust
> addresses according to PCI BAR alignment requirements, converting addresses
> into base and offset values.
> 
> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
> Change from v15 to v16
> - none
> 
> Change from v14 to v15
> - change out address type to dma_addr_t to fix below build issue
> 
> | Reported-by: kernel test robot <lkp@...el.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202502082311.G1hWGggF-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
>    drivers/pci/endpoint/functions/pci-epf-test.c: In function 'pci_epf_test_enable_doorbell':
> >> drivers/pci/endpoint/functions/pci-epf-test.c:726:42: error: passing argument 4 of 'pci_epf_align_inbound_addr' from incompatible pointer type [-Werror=incompatible-pointer-types]
>      726 |                                          &epf_test->db_bar.phys_addr, &offset);
>          |                                          ^~~~~~~~~~~~~~~~~~~~~~~~~~~
>          |                                          |
>          |                                          dma_addr_t * {aka unsigned int *}
>    In file included from include/linux/pci-epc.h:12,
> 
> Change form v9 to v14
> - none
> 
> change from v8 to v9
> - pci_epf_align_inbound_addr(), base and off must be not NULL
> - rm pci_epf_align_inbound_addr_lo_hi()
> 
> change from v7 to v8
> - change name to pci_epf_align_inbound_addr()
> - update comment said only need for memory, which not allocated by
> pci_epf_alloc_space().
> 
> change from v6 to v7
> - new patch
> ---
>  drivers/pci/endpoint/pci-epf-core.c | 44 +++++++++++++++++++++++++++++++++++++
>  include/linux/pci-epf.h             |  3 +++
>  2 files changed, 47 insertions(+)
> 
> diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
> index 95fb3d7c1d45e..33e14a6b1549a 100644
> --- a/drivers/pci/endpoint/pci-epf-core.c
> +++ b/drivers/pci/endpoint/pci-epf-core.c
> @@ -481,6 +481,50 @@ struct pci_epf *pci_epf_create(const char *name)
>  }
>  EXPORT_SYMBOL_GPL(pci_epf_create);
>  
> +/**
> + * pci_epf_align_inbound_addr() - Get base address and offset that match BAR's
> + *			  alignment requirement

'Align the given address based on the BAR alignment requirement'

> + * @epf: the EPF device
> + * @addr: the address of the memory

'inbound address to be aligned'

> + * @bar: the BAR number corresponding to map addr

s/map addr/the given addr

> + * @base: return base address, which match BAR's alignment requirement.

'base address matching the @bar alignment requirement'

> + * @off: return offset.

'offset to be added to the @base address'

> + *
> + * Helper function to convert input 'addr' to base and offset, which match

s/convert/align

> + * BAR's alignment requirement.
> + *
> + * The pci_epf_alloc_space() function already accounts for alignment. This is
> + * primarily intended for use with other memory regions not allocated by
> + * pci_epf_alloc_space(), such as peripheral register spaces or the trigger
> + * address for a platform MSI controller.
> + */
> +int pci_epf_align_inbound_addr(struct pci_epf *epf, enum pci_barno bar,
> +			       u64 addr, dma_addr_t *base, size_t *off)
> +{
> +	const struct pci_epc_features *epc_features;
> +	u64 align;
> +
> +	if (!base || !off)
> +		return -EINVAL;
> +
> +	epc_features = pci_epc_get_features(epf->epc, epf->func_no, epf->vfunc_no);
> +	if (!epc_features) {
> +		dev_err(&epf->dev, "epc_features not implemented\n");
> +		return -EOPNOTSUPP;
> +	}
> +
> +	align = epc_features->align;
> +	align = align ? align : 128;

>From where this 128 byte alignment comes from?

- Mani

-- 
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