linux-kernel - Re: [RFC PATCH 10/17] hwmon: Drop uses of pci_read_config

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Message-ID: <20200804212605.GA218592@roeck-us.net>
Date:   Tue, 4 Aug 2020 14:26:05 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     "Saheed O. Bolarinwa" <refactormyself@...il.com>
Cc:     helgaas@...nel.org, Jean Delvare <jdelvare@...e.com>,
        bjorn@...gaas.com, skhan@...uxfoundation.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hwmon@...r.kernel.org
Subject: Re: [RFC PATCH 10/17] hwmon: Drop uses of pci_read_config_*() return
 value

On Sat, Aug 01, 2020 at 01:24:39PM +0200, Saheed O. Bolarinwa wrote:
> The return value of pci_read_config_*() may not indicate a device error.
> However, the value read by these functions is more likely to indicate
> this kind of error. This presents two overlapping ways of reporting
> errors and complicates error checking.
> 
> It is possible to move to one single way of checking for error if the
> dependency on the return value of these functions is removed, then it
> can later be made to return void.
> 
> Remove all uses of the return value of pci_read_config_*().
> Check the actual value read for ~0. In this case, ~0 is an invalid
> value thus it indicates some kind of error.
> 
> Suggested-by: Bjorn Helgaas <bjorn@...gaas.com>
> Signed-off-by: Saheed O. Bolarinwa <refactormyself@...il.com>

Applied.

Thanks,
Guenter

> ---
>  drivers/hwmon/i5k_amb.c | 12 ++++++++----
>  drivers/hwmon/vt8231.c  |  8 ++++----
>  2 files changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/hwmon/i5k_amb.c b/drivers/hwmon/i5k_amb.c
> index eeac4b04df27..b7497510323c 100644
> --- a/drivers/hwmon/i5k_amb.c
> +++ b/drivers/hwmon/i5k_amb.c
> @@ -427,11 +427,13 @@ static int i5k_find_amb_registers(struct i5k_amb_data *data,
>  	if (!pcidev)
>  		return -ENODEV;
>  
> -	if (pci_read_config_dword(pcidev, I5K_REG_AMB_BASE_ADDR, &val32))
> +	pci_read_config_dword(pcidev, I5K_REG_AMB_BASE_ADDR, &val32);
> +	if (val32 == (u32)~0)
>  		goto out;
>  	data->amb_base = val32;
>  
> -	if (pci_read_config_dword(pcidev, I5K_REG_AMB_LEN_ADDR, &val32))
> +	pci_read_config_dword(pcidev, I5K_REG_AMB_LEN_ADDR, &val32);
> +	if (val32 == (u32)~0)
>  		goto out;
>  	data->amb_len = val32;
>  
> @@ -458,11 +460,13 @@ static int i5k_channel_probe(u16 *amb_present, unsigned long dev_id)
>  	if (!pcidev)
>  		return -ENODEV;
>  
> -	if (pci_read_config_word(pcidev, I5K_REG_CHAN0_PRESENCE_ADDR, &val16))
> +	pci_read_config_word(pcidev, I5K_REG_CHAN0_PRESENCE_ADDR, &val16);
> +	if (val16 == (u16)~0)
>  		goto out;
>  	amb_present[0] = val16;
>  
> -	if (pci_read_config_word(pcidev, I5K_REG_CHAN1_PRESENCE_ADDR, &val16))
> +	pci_read_config_word(pcidev, I5K_REG_CHAN1_PRESENCE_ADDR, &val16);
> +	if (val16 == (u16)~0)
>  		goto out;
>  	amb_present[1] = val16;
>  
> diff --git a/drivers/hwmon/vt8231.c b/drivers/hwmon/vt8231.c
> index 2335d440f72d..6603727e15a0 100644
> --- a/drivers/hwmon/vt8231.c
> +++ b/drivers/hwmon/vt8231.c
> @@ -992,8 +992,8 @@ static int vt8231_pci_probe(struct pci_dev *dev,
>  			return -ENODEV;
>  	}
>  
> -	if (PCIBIOS_SUCCESSFUL != pci_read_config_word(dev, VT8231_BASE_REG,
> -							&val))
> +	pci_read_config_word(dev, VT8231_BASE_REG, &val);
> +	if (val == (u16)~0)
>  		return -ENODEV;
>  
>  	address = val & ~(VT8231_EXTENT - 1);
> @@ -1002,8 +1002,8 @@ static int vt8231_pci_probe(struct pci_dev *dev,
>  		return -ENODEV;
>  	}
>  
> -	if (PCIBIOS_SUCCESSFUL != pci_read_config_word(dev, VT8231_ENABLE_REG,
> -							&val))
> +	pci_read_config_word(dev, VT8231_ENABLE_REG, &val);
> +	if (val == (u16)~0)
>  		return -ENODEV;
>  
>  	if (!(val & 0x0001)) {