linux-kernel - Re: [PATCH v9 2/7] PCI: Apply the new generic I/O management on PCI IO hosts

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Date:   Fri, 26 May 2017 16:20:01 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Gabriele Paoloni <gabriele.paoloni@...wei.com>
Cc:     catalin.marinas@....com, will.deacon@....com, robh+dt@...nel.org,
        frowand.list@...il.com, bhelgaas@...gle.com, rafael@...nel.org,
        arnd@...db.de, linux-arm-kernel@...ts.infradead.org,
        lorenzo.pieralisi@....com, mark.rutland@....com, minyard@....org,
        benh@...nel.crashing.org, john.garry@...wei.com,
        linux-kernel@...r.kernel.org, xuwei5@...ilicon.com,
        linuxarm@...wei.com, linux-acpi@...r.kernel.org,
        "zhichang.yuan" <yuanzhichang@...ilicon.com>,
        linux-pci@...r.kernel.org, olof@...om.net, brian.starkey@....com
Subject: Re: [PATCH v9 2/7] PCI: Apply the new generic I/O management on PCI
 IO hosts

On Thu, May 25, 2017 at 12:37:23PM +0100, Gabriele Paoloni wrote:
> From: "zhichang.yuan" <yuanzhichang@...ilicon.com>
> 
> After introducing the new generic I/O space management(LOGIC_IO), the
> original PCI MMIO relevant helpers need to be updated based on the new
> interfaces defined in LOGIC_IO.
> This patch adapts the corresponding code to match the changes introduced
> by LOGIC_IO.
> 
> Signed-off-by: zhichang.yuan <yuanzhichang@...ilicon.com>
> Signed-off-by: Gabriele Paoloni <gabriele.paoloni@...wei.com>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>        #earlier draft

Not sure how you plan to merge this, but here's my ack:

Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>

If you split this as suggested below, add my ack to all three patches.

> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index b01bd5b..c9fe12b 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
>...

> -int __weak pci_register_io_range(phys_addr_t addr, resource_size_t size)
> +int pci_register_io_range(struct fwnode_handle *fwnode, phys_addr_t addr,
> +			resource_size_t	size)

It's trivial and nit-picky, but I would do the __weak removal in its
own patch.  It's obviously fine because there's only one
implementation, but it's unrelated to the main point of this patch.

I would split the signature change (fwnode addition) to a separate
patch, too, just to make the actual change more obvious, especially
since that's the only part that crosses subsystems (ACPI, PCI, OF).

>  {
> -	int err = 0;
> -
> +	int ret = 0;
>  #ifdef PCI_IOBASE
> -	struct io_range *range;
> -	resource_size_t allocated_size = 0;
> -
> -	/* check if the range hasn't been previously recorded */
> -	spin_lock(&io_range_lock);
> -	list_for_each_entry(range, &io_range_list, list) {
> -		if (addr >= range->start && addr + size <= range->start + size) {
> -			/* range already registered, bail out */
> -			goto end_register;
> -		}
> -		allocated_size += range->size;
> -	}
> -
> -	/* range not registed yet, check for available space */
> -	if (allocated_size + size - 1 > IO_SPACE_LIMIT) {
> -		/* if it's too big check if 64K space can be reserved */
> -		if (allocated_size + SZ_64K - 1 > IO_SPACE_LIMIT) {
> -			err = -E2BIG;
> -			goto end_register;
> -		}
> -
> -		size = SZ_64K;
> -		pr_warn("Requested IO range too big, new size set to 64K\n");
> -	}
> +	struct logic_pio_hwaddr *range;
>  
> -	/* add the range to the list */
> -	range = kzalloc(sizeof(*range), GFP_ATOMIC);
> -	if (!range) {
> -		err = -ENOMEM;
> -		goto end_register;
> -	}
> +	if (!size || addr + size < addr)
> +		return -EINVAL;
>  
> -	range->start = addr;
> +	range = kzalloc(sizeof(*range), GFP_KERNEL);
> +	if (!range)
> +		return -ENOMEM;

Add a blank line here.

> +	range->fwnode = fwnode;
>  	range->size = size;
> +	range->hw_start = addr;
> +	range->flags = PIO_CPU_MMIO;
>  
> -	list_add_tail(&range->list, &io_range_list);
> -
> -end_register:
> -	spin_unlock(&io_range_lock);
> +	ret = logic_pio_register_range(range);
> +	if (ret)
> +		kfree(range);
>  #endif
>  
> -	return err;
> +	return ret;
>  }