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Bolarinwa" , bjorn@helgaas.com, Shuah Khan , linux-kernel-mentees@lists.linuxfoundation.org, linux-pci@vger.kernel.org, LKML , linux-gpio Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Aug 1, 2020 at 2:24 PM 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 > Signed-off-by: Saheed O. Bolarinwa > --- > drivers/gpio/gpio-amd8111.c | 7 +++++-- > drivers/gpio/gpio-rdc321x.c | 21 ++++++++++++--------- > 2 files changed, 17 insertions(+), 11 deletions(-) > > diff --git a/drivers/gpio/gpio-amd8111.c b/drivers/gpio/gpio-amd8111.c > index fdcebe59510d..7b9882380cbc 100644 > --- a/drivers/gpio/gpio-amd8111.c > +++ b/drivers/gpio/gpio-amd8111.c > @@ -198,9 +198,12 @@ static int __init amd_gpio_init(void) > goto out; > > found: > - err = pci_read_config_dword(pdev, 0x58, &gp.pmbase); > - if (err) > + pci_read_config_dword(pdev, 0x58, &gp.pmbase); > + if (gp.pmbase == (u32)~0) { > + err = -ENODEV; > goto out; > + } > + > err = -EIO; > gp.pmbase &= 0x0000FF00; > if (gp.pmbase == 0) > diff --git a/drivers/gpio/gpio-rdc321x.c b/drivers/gpio/gpio-rdc321x.c > index 01ed2517e9fd..03f1ff07b844 100644 > --- a/drivers/gpio/gpio-rdc321x.c > +++ b/drivers/gpio/gpio-rdc321x.c > @@ -85,10 +85,13 @@ static int rdc_gpio_config(struct gpio_chip *chip, > gpch = gpiochip_get_data(chip); > > spin_lock(&gpch->lock); > - err = pci_read_config_dword(gpch->sb_pdev, gpio < 32 ? > - gpch->reg1_ctrl_base : gpch->reg2_ctrl_base, ®); > - if (err) > + pci_read_config_dword(gpch->sb_pdev, > + (gpio < 32) ? gpch->reg1_ctrl_base > + : gpch->reg2_ctrl_base, ®); > + if (reg == (u32)~0) { > + err = -ENODEV; > goto unlock; > + } > > reg |= 1 << (gpio & 0x1f); > > @@ -166,17 +169,17 @@ static int rdc321x_gpio_probe(struct platform_device *pdev) > /* This might not be, what others (BIOS, bootloader, etc.) > wrote to these registers before, but it's a good guess. Still > better than just using 0xffffffff. */ > - err = pci_read_config_dword(rdc321x_gpio_dev->sb_pdev, > + pci_read_config_dword(rdc321x_gpio_dev->sb_pdev, > rdc321x_gpio_dev->reg1_data_base, > &rdc321x_gpio_dev->data_reg[0]); > - if (err) > - return err; > + if (rdc321x_gpio_dev->data_reg[0] == (u32)~0) > + return -ENODEV; > > - err = pci_read_config_dword(rdc321x_gpio_dev->sb_pdev, > + pci_read_config_dword(rdc321x_gpio_dev->sb_pdev, > rdc321x_gpio_dev->reg2_data_base, > &rdc321x_gpio_dev->data_reg[1]); > - if (err) > - return err; > + if (rdc321x_gpio_dev->data_reg[1] == (u32)~0) > + return -ENODEV; > > dev_info(&pdev->dev, "registering %d GPIOs\n", > rdc321x_gpio_dev->chip.ngpio); > -- > 2.18.4 > Bjorn, I don't know the pci sub-system at all. Does this look good to you? Bartosz