netdev - Re: [PATCH v4 2/2] r8169: switch to device-managed functions in probe (part 2)

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Date:   Thu, 1 Mar 2018 20:54:39 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        nic_swsd@...ltek.com, "David S . Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH v4 2/2] r8169: switch to device-managed functions in probe
 (part 2)

Am 01.03.2018 um 12:27 schrieb Andy Shevchenko:
> This is a follow up to the commit
> 
>   4c45d24a759d ("r8169: switch to device-managed functions in probe")
> 
> to move towards managed resources even more.
> 
> Cc: Heiner Kallweit <hkallweit1@...il.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/net/ethernet/realtek/r8169.c | 16 ++++------------
>  1 file changed, 4 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/net/ethernet/realtek/r8169.c b/drivers/net/ethernet/realtek/r8169.c
> index b6098e081a25..7055db161b1b 100644
> --- a/drivers/net/ethernet/realtek/r8169.c
> +++ b/drivers/net/ethernet/realtek/r8169.c
> @@ -8169,7 +8169,6 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
>  	struct rtl8169_private *tp;
>  	struct mii_if_info *mii;
>  	struct net_device *dev;
> -	void __iomem *ioaddr;
>  	int chipset, i;
>  	int rc;
>  
> @@ -8227,20 +8226,13 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
>  		return -ENODEV;
>  	}
>  
> -	rc = pci_request_regions(pdev, MODULENAME);
> +	rc = pcim_iomap_regions(pdev, BIT(region), MODULENAME);
>  	if (rc < 0) {
> -		netif_err(tp, probe, dev, "could not request regions\n");
> +		netif_err(tp, probe, dev, "cannot remap MMIO, aborting\n");
>  		return rc;
>  	}
>  
> -	/* ioremap MMIO region */
> -	ioaddr = devm_ioremap(&pdev->dev, pci_resource_start(pdev, region),
> -			      R8169_REGS_SIZE);
> -	if (!ioaddr) {
> -		netif_err(tp, probe, dev, "cannot remap MMIO, aborting\n");
> -		return -EIO;
> -	}
> -	tp->mmio_addr = ioaddr;
> +	tp->mmio_addr = pcim_iomap_table(pdev)[region];
>  
pcim_iomap_table() can return NULL in case of an error.
Shouldn't we catch this?

Typical benefit of switching to device-managed functions is that we don't
have to clean up in the probe() error path and in remove(). With the
change here we don't have any such benefit and we just exchange two calls
against two other calls w/o functional change (AFAICS).
Which benefit do you see justifying this patch?

However I don't know the PCI API's good enough to be able to judge whether
one set of calls is preferable.


>  	if (!pci_is_pcie(pdev))
>  		netif_info(tp, probe, dev, "not PCI Express\n");
> @@ -8412,7 +8404,7 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
>  	pci_set_drvdata(pdev, dev);
>  
>  	netif_info(tp, probe, dev, "%s at 0x%p, %pM, XID %08x IRQ %d\n",
> -		   rtl_chip_infos[chipset].name, ioaddr, dev->dev_addr,
> +		   rtl_chip_infos[chipset].name, tp->mmio_addr, dev->dev_addr,
>  		   (u32)(RTL_R32(tp, TxConfig) & 0x9cf0f8ff),
>  		   pci_irq_vector(pdev, 0));
>  	if (rtl_chip_infos[chipset].jumbo_max != JUMBO_1K) {
>