linux-kernel - Re: [RFC PATCH 14/35] i2c/busses: Change PCIBIOS

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Message-ID: <20200717165820.6b5318ad@endymion>
Date:   Fri, 17 Jul 2020 16:58:20 +0200
From:   Jean Delvare <jdelvare@...e.de>
To:     "Saheed O. Bolarinwa" <refactormyself@...il.com>
Cc:     helgaas@...nel.org, bjorn@...gaas.com, skhan@...uxfoundation.org,
        linux-pci@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org
Subject: Re: [RFC PATCH 14/35] i2c/busses: Change PCIBIOS_SUCCESSFUL to 0

Hi Saheed,

On Mon, 13 Jul 2020 14:22:26 +0200, Saheed O. Bolarinwa wrote:
> In reference to the PCI spec (Chapter 2), PCIBIOS* is an x86 concept.
> Their scope should be limited within arch/x86.

Which PCI specification are you talking about here. In my "PCI Local
Bus Revision 2.3" specification (March 29, 2002), chapter 2 is about
Signal Definition and has nothing to do with the BIOS.

> 
> Change all PCIBIOS_SUCCESSFUL to 0
> 
> Signed-off-by: "Saheed O. Bolarinwa" <refactormyself@...il.com>
> ---
>  drivers/i2c/busses/i2c-ali15x3.c |  4 ++--
>  drivers/i2c/busses/i2c-nforce2.c |  2 +-
>  drivers/i2c/busses/i2c-sis5595.c | 10 +++++-----
>  3 files changed, 8 insertions(+), 8 deletions(-)

Hmmm. That seems to be a lot of changes to solve an essentially
theoretical problem (if a problem at all). I am not familiar enough
with the PCI subsystem to claim that it is fundamentally wrong, but
enough to say I'm skeptical.

PCI is a cross-architecture standard, and we can't possibly have the
return value of core functions such as pci_write_config_word follow
different conventions depending on the architecture, can we? Does
pci_write_config_word() currently return PCIBIOS_SUCCESSFUL on success
on x86 and 0 on success on other architectures? What about errors, do
we return positive, "PCIBIOS-specific" error codes on x86 and negative,
unix-like error codes on other architectures?

> diff --git a/drivers/i2c/busses/i2c-ali15x3.c b/drivers/i2c/busses/i2c-ali15x3.c
> index 02185a1cfa77..359ee3e0864a 100644
> --- a/drivers/i2c/busses/i2c-ali15x3.c
> +++ b/drivers/i2c/busses/i2c-ali15x3.c
> @@ -167,11 +167,11 @@ static int ali15x3_setup(struct pci_dev *ALI15X3_dev)
>  	if(force_addr) {
>  		dev_info(&ALI15X3_dev->dev, "forcing ISA address 0x%04X\n",
>  			ali15x3_smba);
> -		if (PCIBIOS_SUCCESSFUL != pci_write_config_word(ALI15X3_dev,
> +		if (0 != pci_write_config_word(ALI15X3_dev,
>  								SMBBA,
>  								ali15x3_smba))
>  			goto error;

This leaves the code horribly aligned.

> -		if (PCIBIOS_SUCCESSFUL != pci_read_config_word(ALI15X3_dev,
> +		if (0 != pci_read_config_word(ALI15X3_dev,
>  								SMBBA, &a))
>  			goto error;
>  		if ((a & ~(ALI15X3_SMB_IOSIZE - 1)) != ali15x3_smba) {
> diff --git a/drivers/i2c/busses/i2c-nforce2.c b/drivers/i2c/busses/i2c-nforce2.c
> index 777278386f58..385f4f446f36 100644
> --- a/drivers/i2c/busses/i2c-nforce2.c
> +++ b/drivers/i2c/busses/i2c-nforce2.c
> @@ -328,7 +328,7 @@ static int nforce2_probe_smb(struct pci_dev *dev, int bar, int alt_reg,
>  		u16 iobase;
>  
>  		if (pci_read_config_word(dev, alt_reg, &iobase)
> -		    != PCIBIOS_SUCCESSFUL) {
> +		    != 0) {
>  			dev_err(&dev->dev, "Error reading PCI config for %s\n",
>  				name);
>  			return -EIO;
> diff --git a/drivers/i2c/busses/i2c-sis5595.c b/drivers/i2c/busses/i2c-sis5595.c
> index c793a5c14cda..fbe3ee31eae3 100644
> --- a/drivers/i2c/busses/i2c-sis5595.c
> +++ b/drivers/i2c/busses/i2c-sis5595.c
> @@ -176,10 +176,10 @@ static int sis5595_setup(struct pci_dev *SIS5595_dev)
>  	if (force_addr) {
>  		dev_info(&SIS5595_dev->dev, "forcing ISA address 0x%04X\n", sis5595_base);
>  		if (pci_write_config_word(SIS5595_dev, ACPI_BASE, sis5595_base)
> -		    != PCIBIOS_SUCCESSFUL)
> +		    != 0)
>  			goto error;
>  		if (pci_read_config_word(SIS5595_dev, ACPI_BASE, &a)
> -		    != PCIBIOS_SUCCESSFUL)
> +		    != 0)
>  			goto error;
>  		if ((a & ~(SIS5595_EXTENT - 1)) != sis5595_base) {
>  			/* doesn't work for some chips! */
> @@ -189,15 +189,15 @@ static int sis5595_setup(struct pci_dev *SIS5595_dev)
>  	}
>  
>  	if (pci_read_config_byte(SIS5595_dev, SIS5595_ENABLE_REG, &val)
> -	    != PCIBIOS_SUCCESSFUL)
> +	    != 0)
>  		goto error;
>  	if ((val & 0x80) == 0) {
>  		dev_info(&SIS5595_dev->dev, "enabling ACPI\n");
>  		if (pci_write_config_byte(SIS5595_dev, SIS5595_ENABLE_REG, val | 0x80)
> -		    != PCIBIOS_SUCCESSFUL)
> +		    != 0)
>  			goto error;
>  		if (pci_read_config_byte(SIS5595_dev, SIS5595_ENABLE_REG, &val)
> -		    != PCIBIOS_SUCCESSFUL)
> +		    != 0)
>  			goto error;
>  		if ((val & 0x80) == 0) {
>  			/* doesn't work for some chips? */


-- 
Jean Delvare
SUSE L3 Support