linux-kernel - Re: [PATCH] PCI: mvebu: Use for_each_of_range() iterator for parsing "ranges"

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Message-ID: <20241107170002.wz7wkqmtyqiiaswl@pali>
Date: Thu, 7 Nov 2024 18:00:02 +0100
From: Pali Rohár <pali@...nel.org>
To: "Rob Herring (Arm)" <robh@...nel.org>
Cc: Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: mvebu: Use for_each_of_range() iterator for parsing
 "ranges"

On Thursday 07 November 2024 09:32:55 Rob Herring (Arm) wrote:
> The mvebu "ranges" is a bit unusual with its own encoding of addresses,
> but it's still just normal "ranges" as far as parsing is concerned.
> Convert mvebu_get_tgt_attr() to use the for_each_of_range() iterator
> instead of open coding the parsing.
> 
> Signed-off-by: Rob Herring (Arm) <robh@...nel.org>
> ---
> Compile tested only.

I see no reason for such change, which was even non tested at all and
does not fix any issue. There are more important issues in the driver,
it was decided that bug fixes are not going to be included (yet).

> ---
>  drivers/pci/controller/pci-mvebu.c | 26 +++++++++-----------------
>  1 file changed, 9 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/pci/controller/pci-mvebu.c b/drivers/pci/controller/pci-mvebu.c
> index 29fe09c99e7d..d4e3f1e76f84 100644
> --- a/drivers/pci/controller/pci-mvebu.c
> +++ b/drivers/pci/controller/pci-mvebu.c
> @@ -1179,37 +1179,29 @@ static int mvebu_get_tgt_attr(struct device_node *np, int devfn,
>  			      unsigned int *tgt,
>  			      unsigned int *attr)
>  {
> -	const int na = 3, ns = 2;
> -	const __be32 *range;
> -	int rlen, nranges, rangesz, pna, i;
> +	struct of_range range;
> +	struct of_range_parser parser;
>  
>  	*tgt = -1;
>  	*attr = -1;
>  
> -	range = of_get_property(np, "ranges", &rlen);
> -	if (!range)
> +	if (of_pci_range_parser_init(&parser, np))
>  		return -EINVAL;
>  
> -	pna = of_n_addr_cells(np);
> -	rangesz = pna + na + ns;
> -	nranges = rlen / sizeof(__be32) / rangesz;
> -
> -	for (i = 0; i < nranges; i++, range += rangesz) {
> -		u32 flags = of_read_number(range, 1);
> -		u32 slot = of_read_number(range + 1, 1);
> -		u64 cpuaddr = of_read_number(range + na, pna);
> +	for_each_of_range(&parser, &range) {
>  		unsigned long rtype;
> +		u32 slot = upper_32_bits(range.bus_addr);
>  
> -		if (DT_FLAGS_TO_TYPE(flags) == DT_TYPE_IO)
> +		if (DT_FLAGS_TO_TYPE(range.flags) == DT_TYPE_IO)
>  			rtype = IORESOURCE_IO;
> -		else if (DT_FLAGS_TO_TYPE(flags) == DT_TYPE_MEM32)
> +		else if (DT_FLAGS_TO_TYPE(range.flags) == DT_TYPE_MEM32)
>  			rtype = IORESOURCE_MEM;
>  		else
>  			continue;
>  
>  		if (slot == PCI_SLOT(devfn) && type == rtype) {
> -			*tgt = DT_CPUADDR_TO_TARGET(cpuaddr);
> -			*attr = DT_CPUADDR_TO_ATTR(cpuaddr);
> +			*tgt = DT_CPUADDR_TO_TARGET(range.cpu_addr);
> +			*attr = DT_CPUADDR_TO_ATTR(range.cpu_addr);
>  			return 0;
>  		}
>  	}
> -- 
> 2.45.2
>