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From:   "Saheed O. Bolarinwa" <refactormyself@gmail.com>
To:     helgaas@kernel.org, Wolfram Sang <wsa@kernel.org>
Cc:     "Saheed O. Bolarinwa" <refactormyself@gmail.com>,
        bjorn@helgaas.com, skhan@linuxfoundation.org,
        linux-kernel-mentees@lists.linuxfoundation.org,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-i2c@vger.kernel.org
Subject: [RFC PATCH 12/17] i2c: Drop uses of pci_read_config_*() return value
Date:   Sat,  1 Aug 2020 13:24:41 +0200
Message-Id: <20200801112446.149549-13-refactormyself@gmail.com>
In-Reply-To: <20200801112446.149549-1-refactormyself@gmail.com>
References: <20200801112446.149549-1-refactormyself@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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@helgaas.com>
Signed-off-by: Saheed O. Bolarinwa <refactormyself@gmail.com>
---
 drivers/i2c/busses/i2c-ali15x3.c |  6 ++++--
 drivers/i2c/busses/i2c-elektor.c |  3 ++-
 drivers/i2c/busses/i2c-nforce2.c |  4 ++--
 drivers/i2c/busses/i2c-sis5595.c | 17 +++++++++++------
 drivers/i2c/busses/i2c-sis630.c  |  7 ++++---
 drivers/i2c/busses/i2c-viapro.c  | 11 ++++++-----
 6 files changed, 29 insertions(+), 19 deletions(-)

diff --git a/drivers/i2c/busses/i2c-ali15x3.c b/drivers/i2c/busses/i2c-ali15x3.c
index 02185a1cfa77..fa103131746d 100644
--- a/drivers/i2c/busses/i2c-ali15x3.c
+++ b/drivers/i2c/busses/i2c-ali15x3.c
@@ -171,9 +171,11 @@ static int ali15x3_setup(struct pci_dev *ALI15X3_dev)
 								SMBBA,
 								ali15x3_smba))
 			goto error;
-		if (PCIBIOS_SUCCESSFUL != pci_read_config_word(ALI15X3_dev,
-								SMBBA, &a))
+
+		pci_read_config_word(ALI15X3_dev, SMBBA, &a);
+		if (a == (u16)~0)
 			goto error;
+
 		if ((a & ~(ALI15X3_SMB_IOSIZE - 1)) != ali15x3_smba) {
 			/* make sure it works */
 			dev_err(&ALI15X3_dev->dev,
diff --git a/drivers/i2c/busses/i2c-elektor.c b/drivers/i2c/busses/i2c-elektor.c
index 140426db28df..82c8d6d55561 100644
--- a/drivers/i2c/busses/i2c-elektor.c
+++ b/drivers/i2c/busses/i2c-elektor.c
@@ -207,7 +207,8 @@ static int elektor_match(struct device *dev, unsigned int id)
 		if (cy693_dev) {
 			unsigned char config;
 			/* yeap, we've found cypress, let's check config */
-			if (!pci_read_config_byte(cy693_dev, 0x47, &config)) {
+			pci_read_config_byte(cy693_dev, 0x47, &config);
+			if (config != (u8)~0) {
 
 				dev_dbg(dev, "found cy82c693, config "
 					"register 0x47 = 0x%02x\n", config);
diff --git a/drivers/i2c/busses/i2c-nforce2.c b/drivers/i2c/busses/i2c-nforce2.c
index 777278386f58..dc5d032c5a1d 100644
--- a/drivers/i2c/busses/i2c-nforce2.c
+++ b/drivers/i2c/busses/i2c-nforce2.c
@@ -327,8 +327,8 @@ static int nforce2_probe_smb(struct pci_dev *dev, int bar, int alt_reg,
 		/* Older incarnations of the device used non-standard BARs */
 		u16 iobase;
 
-		if (pci_read_config_word(dev, alt_reg, &iobase)
-		    != PCIBIOS_SUCCESSFUL) {
+		pci_read_config_word(dev, alt_reg, &iobase);
+		if (iobase == (u16)~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..9b3fbde9cd9c 100644
--- a/drivers/i2c/busses/i2c-sis5595.c
+++ b/drivers/i2c/busses/i2c-sis5595.c
@@ -178,9 +178,11 @@ static int sis5595_setup(struct pci_dev *SIS5595_dev)
 		if (pci_write_config_word(SIS5595_dev, ACPI_BASE, sis5595_base)
 		    != PCIBIOS_SUCCESSFUL)
 			goto error;
-		if (pci_read_config_word(SIS5595_dev, ACPI_BASE, &a)
-		    != PCIBIOS_SUCCESSFUL)
+
+		pci_read_config_word(SIS5595_dev, ACPI_BASE, &a);
+		if (a == (u16)~0)
 			goto error;
+
 		if ((a & ~(SIS5595_EXTENT - 1)) != sis5595_base) {
 			/* doesn't work for some chips! */
 			dev_err(&SIS5595_dev->dev, "force address failed - not supported?\n");
@@ -188,17 +190,20 @@ static int sis5595_setup(struct pci_dev *SIS5595_dev)
 		}
 	}
 
-	if (pci_read_config_byte(SIS5595_dev, SIS5595_ENABLE_REG, &val)
-	    != PCIBIOS_SUCCESSFUL)
+	pci_read_config_byte(SIS5595_dev, SIS5595_ENABLE_REG, &val);
+	if (val == (u8)~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)
 			goto error;
-		if (pci_read_config_byte(SIS5595_dev, SIS5595_ENABLE_REG, &val)
-		    != PCIBIOS_SUCCESSFUL)
+
+		pci_read_config_byte(SIS5595_dev, SIS5595_ENABLE_REG, &val);
+		if (val == (u8)~0)
 			goto error;
+
 		if ((val & 0x80) == 0) {
 			/* doesn't work for some chips? */
 			dev_err(&SIS5595_dev->dev, "ACPI enable failed - not supported?\n");
diff --git a/drivers/i2c/busses/i2c-sis630.c b/drivers/i2c/busses/i2c-sis630.c
index cfb8e04a2a83..73b17436f964 100644
--- a/drivers/i2c/busses/i2c-sis630.c
+++ b/drivers/i2c/busses/i2c-sis630.c
@@ -430,7 +430,8 @@ static int sis630_setup(struct pci_dev *sis630_dev)
 	   Enable ACPI first , so we can accsess reg 74-75
 	   in acpi io space and read acpi base addr
 	*/
-	if (pci_read_config_byte(sis630_dev, SIS630_BIOS_CTL_REG, &b)) {
+	pci_read_config_byte(sis630_dev, SIS630_BIOS_CTL_REG, &b);
+	if (b == (u8)~0) {
 		dev_err(&sis630_dev->dev, "Error: Can't read bios ctl reg\n");
 		retval = -ENODEV;
 		goto exit;
@@ -444,8 +445,8 @@ static int sis630_setup(struct pci_dev *sis630_dev)
 	}
 
 	/* Determine the ACPI base address */
-	if (pci_read_config_word(sis630_dev,
-				 SIS630_ACPI_BASE_REG, &acpi_base)) {
+	pci_read_config_word(sis630_dev, SIS630_ACPI_BASE_REG, &acpi_base);
+	if (acpi_base == (u16)~0) {
 		dev_err(&sis630_dev->dev,
 			"Error: Can't determine ACPI base address\n");
 		retval = -ENODEV;
diff --git a/drivers/i2c/busses/i2c-viapro.c b/drivers/i2c/busses/i2c-viapro.c
index 4abc7771af06..14bfa5401845 100644
--- a/drivers/i2c/busses/i2c-viapro.c
+++ b/drivers/i2c/busses/i2c-viapro.c
@@ -321,12 +321,13 @@ static int vt596_probe(struct pci_dev *pdev,
 		goto found;
 	}
 
-	if ((pci_read_config_word(pdev, id->driver_data, &vt596_smba)) ||
-	    !(vt596_smba & 0x0001)) {
+	pci_read_config_word(pdev, id->driver_data, &vt596_smba);
+	if ((vt596_smba == (u16)~0) || !(vt596_smba & 0x0001)) {
 		/* try 2nd address and config reg. for 596 */
-		if (id->device == PCI_DEVICE_ID_VIA_82C596_3 &&
-		    !pci_read_config_word(pdev, SMBBA2, &vt596_smba) &&
-		    (vt596_smba & 0x0001)) {
+		pci_read_config_word(pdev, SMBBA2, &vt596_smba);
+		if ((id->device == PCI_DEVICE_ID_VIA_82C596_3) &&
+					(vt596_smba != (u16)~0) &&
+					(vt596_smba & 0x0001)) {
 			SMBHSTCFG = 0x84;
 		} else {
 			/* no matches at all */
-- 
2.18.4